Effectiveness of paper deacidification processes

ISO/TS 18344:2016 defines test methods and minimum requirements for paper deacidification processes regarding their effectiveness and consistency. It is applicable for all large scale processes which offer deacidification of acid documents made of printed or hand-written paper. Possible negative side effects of deacidification processes on the treated objects are not the subject of this Technical Specification. However, some general recommendations for how to cope with these side effects are given in Annex A. It is not specified either, which types of paper objects can be treated by large scale deacidification methods. Whatever currently available deacidification method is used, some objects might be excluded from treatment to avoid mechanical damage to paper and bindings or other unwanted side effects. The provider of the deacidification treatment should inform the customer about the limitations of the chosen method.

Efficacité des procédés de désacidification du papier

Učinkovitost postopkov za razkisanje papirja

Te tehnične specifikacije opredeljujejo preskusne metode in minimalne zahteve glede učinkovitosti in konsistentnosti postopkov za razkisanje papirja.
Uporabljajo se za vse postopke v velikem obsegu, ki ponujajo razkisanje kislih dokumentov na potiskanem ali ročno popisanem papirju.
Možni negativni stranki učinki postopkov za razkisanje na obdelane predmete niso predmet teh tehničnih specifikacij. Vendar pa je v dodatku A podanih nekaj splošni priporočil za soočanje s tem stranskimi učinki.
Prav tako ni določeno, katere vrste papirnatih predmetov je mogoče obdelovati z metodami za razkisanje v velikem obsegu. Nekateri predmeti so morda izključeni iz obdelave, da se prepreči mehanske poškodbe papirja in vezave ali druge neželene stranske učinke, ne glede na to, katera trenutno razpoložljiva metoda je uporabljena.
Ponudnik obdelave za razkisanje mora stranko obvestiti o omejitvah izbrane metode.

General Information

Status
Published
Publication Date
03-Feb-2016
Current Stage
6060 - International Standard published
Start Date
08-Oct-2015
Completion Date
04-Feb-2016

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TECHNICAL ISO/TS
SPECIFICATION 18344
First edition
2016-02-01
Effectiveness of paper deacidification
processes
Efficacité des procédés de désacidification du papier
Reference number
ISO/TS 18344:2016(E)
ISO 2016
---------------------- Page: 1 ----------------------
ISO/TS 18344:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 18344:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 3

5 Requirements .......................................................................................................................................................................................................... 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Sampling ....................................................................................................................................................................................................... 3

5.2.1 Material .................................................................................................................................................................................... 3

5.2.2 Procedure ............................................................................................................................................................................... 4

5.3 Process validation ................................................................................................................................................................................ 4

5.3.1 Frequency of sampling................................................................................................................................................ 4

5.3.2 Sample quantities and preparation of samples ..................................................................................... 4

5.3.3 Test methods and minimum requirements .............................................................................................. 5

5.4 Routine monitoring ............................................................................................................................................................................. 8

5.4.1 Frequency of sampling and sample quantities ...................................................................................... 8

5.4.2 Test methods and minimum requirements .............................................................................................. 8

6 Report .............................................................................................................................................................................................................................. 8

Annex A (informative) Negative side effects and insufficient deacidification ........................................................10

Annex B (informative) Sample forms for documentation ...........................................................................................................11

Bibliography .............................................................................................................................................................................................................................17

© ISO 2016 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/TS 18344:2016(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 46, Information and documentation,

Subcommittee SC 10, Requirements for document storage and conditions for preservation.

iv © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 18344:2016(E)
Introduction

Archives, libraries and similar institutions store written and printed documents which they are

obliged to retain on a permanent basis for cultural reasons and, in some cases, in order to meet legal

requirements.

Often, the condition of these documents is endangered for a number of reasons. One of these is related

to the manufacturing process used for more modern types of paper.

In the industrial age, paper-making processes underwent significant changes. One of the processes

affected was sizing, which, in industrial processes, was achieved by mixing additives into the fibre

suspension before shaping the sheets. These additives included acidic substances like aluminium

sulfate. The reaction of the sizing agent eventually leads to formation of free acids. The acids act as a

catalyst for the hydrolysis of cellulose, making the material brittle. Climatic influences aggravate this

process, air pollution and cellulose degradation processes are a further source of acid in paper.

Another factor for paper stability is the raw material itself. For centuries, paper was made of textile

fibres like linen, hemp or cotton rags which rather deliver stable, long-chain cellulose. The search for a

more abundant raw material led to the invention to produce pulp out of wood by a grinding process. The

resulting ground wood paper still contains most of the lignin and hemicelluloses, in addition to cellulose.

The low pulp purity and the mechanical process causing a partial cutting of fibres lead to a much weaker

paper. Compared to the older rag papers, ground wood paper is also less stable on the long run.

The problem of paper degradation due to acid has developed into a tremendous problem for archives

and libraries. In addition to the processes for deacidifying single sheets, such processes having been

used in conservation for a long time, the past few decades have seen new developments in technical

processes which can be used on a large scale to retard the further decay of cultural assets as bound

volumes and single sheets (“mass deacidification”).

The aim of deacidification is to appreciably improve the life expectancy of paper. This is achieved by

adding an alkaline substance to neutralize existing acid and slow down future acidic degradation for

at least some time (buffering, alkaline reserve). Deacidification cannot improve the actual physical

properties of the paper, but in combination with proper storage, it can slow down further decay.

Without validated analytical methods, it is not possible to assess whether a paper has been deacidified,

or to what degree deacidification has been successful. This Technical Specification compiles the suitable

measurements.
© ISO 2016 – All rights reserved v
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TECHNICAL SPECIFICATION ISO/TS 18344:2016(E)
Effectiveness of paper deacidification processes
1 Scope

This Technical Specification defines test methods and minimum requirements for paper deacidification

processes regarding their effectiveness and consistency.

It is applicable for all large scale processes which offer deacidification of acid documents made of

printed or hand-written paper.

Possible negative side effects of deacidification processes on the treated objects are not the subject of

this Technical Specification. However, some general recommendations for how to cope with these side

effects are given in Annex A.

It is not specified either, which types of paper objects can be treated by large scale deacidification

methods. Whatever currently available deacidification method is used, some objects might be excluded

from treatment to avoid mechanical damage to paper and bindings or other unwanted side effects.

The provider of the deacidification treatment should inform the customer about the limitations of the

chosen method.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 535, Paper and board — Determination of water absorptiveness — Cobb method
ISO 536, Paper and board — Determination of grammage
ISO 776, Pulps — Determination of acid-insoluble ash

ISO 5351:2010, Pulps — Determination of limiting viscosity number in cupri-ethylenediamine (CED) solution

ISO 5626, Paper — Determination of folding endurance

ISO 5630-5:2008, Paper and board — Accelerated ageing — Part 5: Exposure to elevated temperature at

100 degrees C

ISO 6588-1, Paper, board and pulps — Determination of pH of aqueous extracts — Part 1: Cold extraction

ISO 9184-1, Paper, board and pulps — Fibre furnish analysis — Part 1: General method

ISO 9184-4, Paper, board and pulps — Fibre furnish analysis — Part 4: Graff “C” staining test

ISO 10716, Paper and board — Determination of alkali reserve
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
3.1
accelerated ageing

artificially induced ageing under laboratory condition by increasing temperature and sometimes

changing humidity or exposure to light in order to accelerate chemical reactions in paper like hydrolysis

or oxidation to simulate processes usually occurring under natural condition but at a much slower speed

© ISO 2016 – All rights reserved 1
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ISO/TS 18344:2016(E)
3.2
alkaline reserve
compound like calcium or magnesium carbonate neutralizing acids in paper
3.3
average degree of polymerisation

average number of anhydroglucose units (monomers of cellulose) in the cellulose macromolecule

3.4
batch process
deacidification process for a definite quantity of documents
3.5
continuous process
deacidification process for an indefinite quantity of documents
3.6
deacidification

neutralization of the organic and inorganic acids in the paper and deposit of an alkaline reserve as

buffer against any subsequent acidic activity on paper
3.7
extract pH

value obtained in a water extract after the paper has been extracted under defined condition.

Note 1 to entry: Value measured with a glass electrode immersed in a definite quantity of water in which paper

is dispersed in small pieces.
3.8
folding endurance

common logarithm of the number of double folds required to cause rupture in a strip of paper

3.9
mass deacidification
process of paper deacidification on a large scale
3.10
process validation

securing an operation according to preset parameters determined at processed objects

3.11
routine monitoring
monitoring carried out at regular intervals during normal operations
3.12
side effects
any unintended consequence caused by the execution of a treatment process
3.13
test paper

paper with characteristics defined in this Technical Specification, which is deacidified together with

original documents and then analysed
3.14
uniformity of deacidification

homogeneous distribution of the alkaline reserve and pH across the entire sheet and within whole book

blocks
2 © ISO 2016 – All rights reserved
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ISO/TS 18344:2016(E)
4 Principle

Specified uniform test papers are treated together with customer’s documents in a deacidification

process. Afterwards, the test papers are examined using standardized test methods. The test papers

are acidic and similar in their properties to common paper qualities produced in the period from

around 1870 onwards. The usage of such papers ensures reliable results and allows comparing different

batches, deacidification methods and treatment plants.

NOTE It is to be emphasized that successful tests according to this Technical Specification cannot guarantee

that all documents treated in the process are deacidified to the same degree as the test papers. The result of a

deacidification treatment strongly depends on the properties of the treated object, such as porosity, thickness,

sizing, coating and acidity of the paper, etc. Therefore, it is impossible to guarantee that certain pH levels and

alkaline reserve amounts are achieved in each object by the deacidification treatment. A passing of the tests

means, however, that there is a high percentage of successfully treated objects.
5 Requirements
5.1 General

This Technical Specification defines test methods for “process validation” (initial testing) and “routine

monitoring”. Process validation is used to prove that a technique fulfils its defined purpose. Routine

monitoring is used to check that the effectiveness determined by process validation is being achieved in

the course of the actual work. Routine monitoring, therefore, is based on process validation.

For “process validation”, extended test procedures should be carried out before and after accelerated

ageing of the samples, including measurements of pH value, alkaline reserve, uniformity of

deacidification and degree of polymerisation.
For “routine monitoring”, alkaline reserve of the test papers is examined.
5.2 Sampling
5.2.1 Material

Both process validation and routine monitoring are performed using samples of test paper, some of

which are deliberately not subjected to the deacidification process serving as a reference.

Table 1 — Test paper
Test paper According to ISO standard
(ground wood-free)

Fibrous material Fully bleached sulphite pulp with hemicelluloses ISO 9184-1, ISO 9184-4

Kaolin filler 12 %–15 % kaolin ISO 776
Grammage 80 g/m ISO 536
Surface finish none none
Sizing approximately Cobb 60’ 20 g/m ISO 535
Type of sizing Alum rosin sizing Al (SO ) none
2 4 3
Surface sizing none none
Extract pH approximately 5 ISO 6588-1
Optical brighteners none none
Acidity, given as negative approximately −0,3 % MgCO
alkaline reserve

Since no ISO standard is available, the German technical specification Zellcheming ZM IV/58/80 “Prüfung von Papier,

Karton und Pappe…” can be applied. See Reference [2].
© ISO 2016 – All rights reserved 3
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ISO/TS 18344:2016(E)
5.2.2 Procedure

All samples should be examined within four weeks after treatment has been completed (including post

treatment measures).

Before the paper is examined, any loose residues occurring as a side effect of the deacidification process

should be removed by brushing.
5.3 Process validation
5.3.1 Frequency of sampling

A complete process validation is required every four years and, additionally, following

— changes to the process technology,
— changes of chemical components or their supplier, or
— changes of the test paper for routine monitoring.

The process validation is valid for all treatment devices of a production site that use the same process

and technology.
5.3.2 Sample quantities and preparation of samples

The process validation is performed using identical test papers (i.e. same production batch). A quantity

of 32 (+4, if folding endurance is included) test sheets, size A5 or larger, is needed for the necessary

testing (see Table 2) of one treated sample set. Four treated sample sets are necessary for the process

validation. The untreated sample set included, the sum of test sheets for one complete process validation

is therefore 148 (+20, if folding endurance is included).
Table 2 — Tested qualities and numbers of test sheets needed
untreated test paper treated test paper
Tested quality (one untreated sample set) (one treated sample set)
unaged aged unaged aged
pH value
4 4 4 4
(cold extraction)
Alkaline reserve 4 4 4 4
Uniformity of deacidi-
12 —
fication
Cellulose DP 2 2 2 2
Folding endurance (op-
(2) (2) (2) (2)
tional)

For batch processes, the test papers should be placed into bound volumes which are thicker than 3 cm

and feature a size of at least A5. For the first sample set, 32 (+4) test papers are placed evenly throughout

the bound volume starting from page number 10.

The test papers should be centred vertically and placed as close to the spine as possible. The test papers

should not extend outside the book block. The second sample set is prepared the same way, but placed

in a different position in the treatment chamber. The third and fourth sample set should be treated on

another day, and if applicable, in another treatment device. The positions of the samples in the chamber

should be documented adequately.

NOTE Service providers can supply a constructional drawing of the deacidification device with the report

and mark the positions of the books containing the test papers.
4 © ISO 2016 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/TS 18344:2016(E)

For continuous processes, the test papers of one sample set should be treated alternating with sheets of

original items. After further treatment of 100 sheets of original items, the second sample set should be

treated to the same pattern as the first. The third and fourth sample sets should be treated according to

the first two sample sets, but on a different day, and, if applicable, in another device.

5.3.3 Test methods and minimum requirements
5.3.3.1 Accelerated ageing

Perform accelerated ageing of 10 (+2) test sheets of each of the four sample sets and 10 (+2) untreated

test sheets as described in ISO 5630-5:2008, Clause 4 to 9.2.

Test tubes selected for this study shall be perfectly gas-tight and large enough to accommodate paper

strips pre-cut for further measurements. It is required to perform aging for all samples simultaneously,

in the same laboratory oven, using one type of a glass tube for all samples.

NOTE To ensure perfect airtightness of testing tubes, the following steps could be taken:

— original tube caps supplied with glass tubes could be exchanged for caps made of material with higher

resistance to mechanical and thermal stresses (e.g. polyphenylsiloxane);

— sealing material – PTFE or silicone gaskets and o-rings should be avoided, fluoroelastomers are advisable

(e.g. Viton);

— tightening of the tube with the use of the dynamometric wrench equipped with a tube cap holder, to ensure

good repeatability of obtained sealing.
5.3.3.2 pH value

The pH value has to be measured in an aqueous extract as described in ISO 6588-1.

The average results and the average and the relative standard deviations should be given for treated

paper with and without ageing, and the results should be expressed to two significant digits.

The measured pH of the paper following deacidification has to be higher than 6,5 (before accelerated

ageing).

NOTE 1 The pH value of an aged sample will normally be lower compared to those of the non-aged sample. For

a given paper, ageing after deacidification should only lead to a small reduction of its pH value. It is possible that

the pH value measured after accelerated ageing will level out at around 6,5, even though an alkaline reserve is

still present. This is particularly true of the pH value on the paper surface which is usually one unit lower than

the pH value of the cold extract. Under these conditions, however, this kind of paper can still be described as

being neutral.

The pH value discussed here applies solely to the described test papers. If original papers are examined

as well, special agreements on an acceptable final pH value should be reached with the customer, as the

achieved pH value depends very much on the original composition of the paper.

NOTE 2 In addition to this measurement of aqueous extract pH value, measurements of surface pH value are

sometimes performed. The surface pH measurement is a faster method compared to extraction pH measurement

to judge the pH value of a paper. If applied correctly (see Reference [3]), surface pH measurements also allow on-

site measurements of original books and documents in libraries and archives and can also be used to follow the

stability of deacidification on a longer timescale. However, surface pH measurement has its limits. It works well

for acidic to neutral papers and also gives reasonable data until about pH 9. Usually, surface pH measurement has

been successfully used with immersion treatments. Surface pH measurement may fail to give reliable results when

larger amounts of alkaline reserve deposits are present at the paper surface and the solubility limit is reached.

5.3.3.3 Alkaline reserve

Determine the quantity of alkaline reserve of each of the four sample sets as described in ISO 10716.

For determination of the dry matter content, it is in deviation to ISO 10716 sufficient for the purpose of

this Technical Specification to weigh about 1 g to the nearest 0,001 g.
© ISO 2016 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/TS 18344:2016(E)

The results, the average and the relative standard deviation should be given for treated paper with and

without ageing, and the results should be expressed to two significant digits.
The minimum alkaline reserve is 0,5 mass % expressed as MgCO .

NOTE Part of the total amount of alkaline substance applied to the paper by deacidification treatment is

chemically converted (“consumed”) by the neutralization reaction, and the remainder is the “alkaline reserve”.

The alkaline reserve ensures that the paper is resistant to acids acting upon it due to environmental influences

or degradation reactions occurring after the deacidification process.
5.3.3.4 Uniformity of deacidification

The uniformity of deacidification is measured by quantitative determination of the alkaline reserve,

expressed as mass % MgCO , at six different segments of a treated sample. Figure 1 shows the cutting

pattern for the segments.

Figure 1 — Segments for the determination of alkaline reserve for uniformity test

As one A5 sheet of test paper is not sufficient for analysing uniformity due to the limited sample

amount (for alkaline reserve 1 g of sample is required per data point), the measurement of the alkaline

reserve of the six treated paper samples is carried out as described in ISO 10716, with the following

amendments: Three A5 test paper sheets are cut into six rectangular, numbered segments of equal size

according to the pattern shown in Figure 1. Then, the three pieces with same numbers are put together,

divided into small pieces as described in ISO 10716, and the resulting pile is mixed well. About 1 g of

pieces is weighed and treated as described in ISO 10716.

Alkaline reserve measured for each section should be not less than 0,5 % by weight calculated as

MgCO equivalent. In addition, the relative standard deviation of the six individual measured values is

required to be less than 30 %. The lower the deviation calculated in this way, the better the uniformity

of deacidification.

NOTE 1 The results of these measurements describe the distribution of the added alkaline substance over the

entire surface area of the sheet of paper, not its homogeneous distribution across its thickness/cross section. For

the latter, no standardized routine methods are available.

NOTE 2 Some alternative methods exist which are able to address the uptake of deacidification reagent, in

most cases, the concentration of cations is analysed. However, these methods do not suffice as a full displacement

of alkaline reserve determination, as most of them are not fully comparable with the actual amount of alkaline

reserve. However, to estimate whether mass deacidification was homogeneous they can serve as alternative.

Potential methods are based on inductively coupled plasma optical spectrometry (ICP/OES) after the alkaline

reserve was extracted by acid from the paper segments, X-ray-Fluorescence scanning or FTIR/NIR and other

methods which reliably report the uptake of deacidification reagent.
6 © ISO 2016 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/TS 18344:2016(E)
5.3.3.5 Degree of polymerisation

A pretreatment to remove the excess of alkaline reserve in the sample has to be performed as follows:

Disintegrate 1 g to 3 g of paper sample in a mixer for less than 30 s directly in 1,5 L, 0,1 M HCl at room

temperature (for 3 g of paper sample with 2 % alkaline reserve this corresponds to >200 fold excess of

acid when 1,5L are used). Rinse the sample thoroughly with water until washing water is neutral. Dry

sample at room conditions according to ISO 5351:2010, Clause 8. The sample preparation should be

adapted to the ingredients of the deacidification process.

NOTE 1 ISO 5351:2010, Clause 8 requires 10 g of material, but 1 g is sufficient for the DP sample preparation in

the present case.

Determine the degree of polymerisation by measuring the viscosity average with CED as described

in ISO 5351 before and after accelerated ageing. For determination of the dry matter content, it is in

deviation to ISO 5351 sufficient for the purpose of this Technical Specification to weigh about 1 g to the

nearest 0,001 g. The average results of the limiting viscosity number should be given for treated and

untreated papers with and without ageing, and the results should be expressed in millilitres per gram.

After accelerated ageing, the limiting viscosity number of the treated paper has to be higher than that

of the untreated paper.

NOTE 2 When looking at different deacidification treatments, the ratios of the limiting viscosity numbers of

treated versus untreated papers after ageing can be compared if identical test papers are used.

For the calculation of DP, a [η]-DP relation for cellulose dissolved in CED is given in the formula below.

0,9

The limiting viscosity number is converted to degree of polymerisation by DP = √(1,65 × [η]) (see

Reference [5]).

NOTE 3 The degree of polymerisation describes the average chain length of a polymer, in case of paper that

of the mixture of cellulose and hemicelluloses. As the stability of paper is directly related to the chain lengths

of (hemi) cellulose (longer polymer chains usually give stronger papers) this parameter can be considered as

very important for the entire integrity of paper. In addition, it is a sensitive measure of cellulose degradation and

hence very useful to address changes upon aging before and after deacidification. The sample amount required

for analysis ranges between 75 mg and 750 mg for a triple deter
...

SLOVENSKI STANDARD
SIST-TS ISO/TS 18344:2018
01-september-2018
8þLQNRYLWRVWSRVWRSNRY]DUD]NLVDQMHSDSLUMD
Effectiveness of paper deacidification processes
Efficacité des procédés de désacidification du papier
Ta slovenski standard je istoveten z: ISO/TS 18344:2016
ICS:
01.140.20 Informacijske vede Information sciences
85.080.01 Papirni izdelki na splošno Paper products in general
SIST-TS ISO/TS 18344:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST-TS ISO/TS 18344:2018
---------------------- Page: 2 ----------------------
SIST-TS ISO/TS 18344:2018
TECHNICAL ISO/TS
SPECIFICATION 18344
First edition
2016-02-01
Effectiveness of paper deacidification
processes
Efficacité des procédés de désacidification du papier
Reference number
ISO/TS 18344:2016(E)
ISO 2016
---------------------- Page: 3 ----------------------
SIST-TS ISO/TS 18344:2018
ISO/TS 18344:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
SIST-TS ISO/TS 18344:2018
ISO/TS 18344:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 3

5 Requirements .......................................................................................................................................................................................................... 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Sampling ....................................................................................................................................................................................................... 3

5.2.1 Material .................................................................................................................................................................................... 3

5.2.2 Procedure ............................................................................................................................................................................... 4

5.3 Process validation ................................................................................................................................................................................ 4

5.3.1 Frequency of sampling................................................................................................................................................ 4

5.3.2 Sample quantities and preparation of samples ..................................................................................... 4

5.3.3 Test methods and minimum requirements .............................................................................................. 5

5.4 Routine monitoring ............................................................................................................................................................................. 8

5.4.1 Frequency of sampling and sample quantities ...................................................................................... 8

5.4.2 Test methods and minimum requirements .............................................................................................. 8

6 Report .............................................................................................................................................................................................................................. 8

Annex A (informative) Negative side effects and insufficient deacidification ........................................................10

Annex B (informative) Sample forms for documentation ...........................................................................................................11

Bibliography .............................................................................................................................................................................................................................17

© ISO 2016 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST-TS ISO/TS 18344:2018
ISO/TS 18344:2016(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 46, Information and documentation,

Subcommittee SC 10, Requirements for document storage and conditions for preservation.

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Introduction

Archives, libraries and similar institutions store written and printed documents which they are

obliged to retain on a permanent basis for cultural reasons and, in some cases, in order to meet legal

requirements.

Often, the condition of these documents is endangered for a number of reasons. One of these is related

to the manufacturing process used for more modern types of paper.

In the industrial age, paper-making processes underwent significant changes. One of the processes

affected was sizing, which, in industrial processes, was achieved by mixing additives into the fibre

suspension before shaping the sheets. These additives included acidic substances like aluminium

sulfate. The reaction of the sizing agent eventually leads to formation of free acids. The acids act as a

catalyst for the hydrolysis of cellulose, making the material brittle. Climatic influences aggravate this

process, air pollution and cellulose degradation processes are a further source of acid in paper.

Another factor for paper stability is the raw material itself. For centuries, paper was made of textile

fibres like linen, hemp or cotton rags which rather deliver stable, long-chain cellulose. The search for a

more abundant raw material led to the invention to produce pulp out of wood by a grinding process. The

resulting ground wood paper still contains most of the lignin and hemicelluloses, in addition to cellulose.

The low pulp purity and the mechanical process causing a partial cutting of fibres lead to a much weaker

paper. Compared to the older rag papers, ground wood paper is also less stable on the long run.

The problem of paper degradation due to acid has developed into a tremendous problem for archives

and libraries. In addition to the processes for deacidifying single sheets, such processes having been

used in conservation for a long time, the past few decades have seen new developments in technical

processes which can be used on a large scale to retard the further decay of cultural assets as bound

volumes and single sheets (“mass deacidification”).

The aim of deacidification is to appreciably improve the life expectancy of paper. This is achieved by

adding an alkaline substance to neutralize existing acid and slow down future acidic degradation for

at least some time (buffering, alkaline reserve). Deacidification cannot improve the actual physical

properties of the paper, but in combination with proper storage, it can slow down further decay.

Without validated analytical methods, it is not possible to assess whether a paper has been deacidified,

or to what degree deacidification has been successful. This Technical Specification compiles the suitable

measurements.
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TECHNICAL SPECIFICATION ISO/TS 18344:2016(E)
Effectiveness of paper deacidification processes
1 Scope

This Technical Specification defines test methods and minimum requirements for paper deacidification

processes regarding their effectiveness and consistency.

It is applicable for all large scale processes which offer deacidification of acid documents made of

printed or hand-written paper.

Possible negative side effects of deacidification processes on the treated objects are not the subject of

this Technical Specification. However, some general recommendations for how to cope with these side

effects are given in Annex A.

It is not specified either, which types of paper objects can be treated by large scale deacidification

methods. Whatever currently available deacidification method is used, some objects might be excluded

from treatment to avoid mechanical damage to paper and bindings or other unwanted side effects.

The provider of the deacidification treatment should inform the customer about the limitations of the

chosen method.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 535, Paper and board — Determination of water absorptiveness — Cobb method
ISO 536, Paper and board — Determination of grammage
ISO 776, Pulps — Determination of acid-insoluble ash

ISO 5351:2010, Pulps — Determination of limiting viscosity number in cupri-ethylenediamine (CED) solution

ISO 5626, Paper — Determination of folding endurance

ISO 5630-5:2008, Paper and board — Accelerated ageing — Part 5: Exposure to elevated temperature at

100 degrees C

ISO 6588-1, Paper, board and pulps — Determination of pH of aqueous extracts — Part 1: Cold extraction

ISO 9184-1, Paper, board and pulps — Fibre furnish analysis — Part 1: General method

ISO 9184-4, Paper, board and pulps — Fibre furnish analysis — Part 4: Graff “C” staining test

ISO 10716, Paper and board — Determination of alkali reserve
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
3.1
accelerated ageing

artificially induced ageing under laboratory condition by increasing temperature and sometimes

changing humidity or exposure to light in order to accelerate chemical reactions in paper like hydrolysis

or oxidation to simulate processes usually occurring under natural condition but at a much slower speed

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3.2
alkaline reserve
compound like calcium or magnesium carbonate neutralizing acids in paper
3.3
average degree of polymerisation

average number of anhydroglucose units (monomers of cellulose) in the cellulose macromolecule

3.4
batch process
deacidification process for a definite quantity of documents
3.5
continuous process
deacidification process for an indefinite quantity of documents
3.6
deacidification

neutralization of the organic and inorganic acids in the paper and deposit of an alkaline reserve as

buffer against any subsequent acidic activity on paper
3.7
extract pH

value obtained in a water extract after the paper has been extracted under defined condition.

Note 1 to entry: Value measured with a glass electrode immersed in a definite quantity of water in which paper

is dispersed in small pieces.
3.8
folding endurance

common logarithm of the number of double folds required to cause rupture in a strip of paper

3.9
mass deacidification
process of paper deacidification on a large scale
3.10
process validation

securing an operation according to preset parameters determined at processed objects

3.11
routine monitoring
monitoring carried out at regular intervals during normal operations
3.12
side effects
any unintended consequence caused by the execution of a treatment process
3.13
test paper

paper with characteristics defined in this Technical Specification, which is deacidified together with

original documents and then analysed
3.14
uniformity of deacidification

homogeneous distribution of the alkaline reserve and pH across the entire sheet and within whole book

blocks
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4 Principle

Specified uniform test papers are treated together with customer’s documents in a deacidification

process. Afterwards, the test papers are examined using standardized test methods. The test papers

are acidic and similar in their properties to common paper qualities produced in the period from

around 1870 onwards. The usage of such papers ensures reliable results and allows comparing different

batches, deacidification methods and treatment plants.

NOTE It is to be emphasized that successful tests according to this Technical Specification cannot guarantee

that all documents treated in the process are deacidified to the same degree as the test papers. The result of a

deacidification treatment strongly depends on the properties of the treated object, such as porosity, thickness,

sizing, coating and acidity of the paper, etc. Therefore, it is impossible to guarantee that certain pH levels and

alkaline reserve amounts are achieved in each object by the deacidification treatment. A passing of the tests

means, however, that there is a high percentage of successfully treated objects.
5 Requirements
5.1 General

This Technical Specification defines test methods for “process validation” (initial testing) and “routine

monitoring”. Process validation is used to prove that a technique fulfils its defined purpose. Routine

monitoring is used to check that the effectiveness determined by process validation is being achieved in

the course of the actual work. Routine monitoring, therefore, is based on process validation.

For “process validation”, extended test procedures should be carried out before and after accelerated

ageing of the samples, including measurements of pH value, alkaline reserve, uniformity of

deacidification and degree of polymerisation.
For “routine monitoring”, alkaline reserve of the test papers is examined.
5.2 Sampling
5.2.1 Material

Both process validation and routine monitoring are performed using samples of test paper, some of

which are deliberately not subjected to the deacidification process serving as a reference.

Table 1 — Test paper
Test paper According to ISO standard
(ground wood-free)

Fibrous material Fully bleached sulphite pulp with hemicelluloses ISO 9184-1, ISO 9184-4

Kaolin filler 12 %–15 % kaolin ISO 776
Grammage 80 g/m ISO 536
Surface finish none none
Sizing approximately Cobb 60’ 20 g/m ISO 535
Type of sizing Alum rosin sizing Al (SO ) none
2 4 3
Surface sizing none none
Extract pH approximately 5 ISO 6588-1
Optical brighteners none none
Acidity, given as negative approximately −0,3 % MgCO
alkaline reserve

Since no ISO standard is available, the German technical specification Zellcheming ZM IV/58/80 “Prüfung von Papier,

Karton und Pappe…” can be applied. See Reference [2].
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5.2.2 Procedure

All samples should be examined within four weeks after treatment has been completed (including post

treatment measures).

Before the paper is examined, any loose residues occurring as a side effect of the deacidification process

should be removed by brushing.
5.3 Process validation
5.3.1 Frequency of sampling

A complete process validation is required every four years and, additionally, following

— changes to the process technology,
— changes of chemical components or their supplier, or
— changes of the test paper for routine monitoring.

The process validation is valid for all treatment devices of a production site that use the same process

and technology.
5.3.2 Sample quantities and preparation of samples

The process validation is performed using identical test papers (i.e. same production batch). A quantity

of 32 (+4, if folding endurance is included) test sheets, size A5 or larger, is needed for the necessary

testing (see Table 2) of one treated sample set. Four treated sample sets are necessary for the process

validation. The untreated sample set included, the sum of test sheets for one complete process validation

is therefore 148 (+20, if folding endurance is included).
Table 2 — Tested qualities and numbers of test sheets needed
untreated test paper treated test paper
Tested quality (one untreated sample set) (one treated sample set)
unaged aged unaged aged
pH value
4 4 4 4
(cold extraction)
Alkaline reserve 4 4 4 4
Uniformity of deacidi-
12 —
fication
Cellulose DP 2 2 2 2
Folding endurance (op-
(2) (2) (2) (2)
tional)

For batch processes, the test papers should be placed into bound volumes which are thicker than 3 cm

and feature a size of at least A5. For the first sample set, 32 (+4) test papers are placed evenly throughout

the bound volume starting from page number 10.

The test papers should be centred vertically and placed as close to the spine as possible. The test papers

should not extend outside the book block. The second sample set is prepared the same way, but placed

in a different position in the treatment chamber. The third and fourth sample set should be treated on

another day, and if applicable, in another treatment device. The positions of the samples in the chamber

should be documented adequately.

NOTE Service providers can supply a constructional drawing of the deacidification device with the report

and mark the positions of the books containing the test papers.
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For continuous processes, the test papers of one sample set should be treated alternating with sheets of

original items. After further treatment of 100 sheets of original items, the second sample set should be

treated to the same pattern as the first. The third and fourth sample sets should be treated according to

the first two sample sets, but on a different day, and, if applicable, in another device.

5.3.3 Test methods and minimum requirements
5.3.3.1 Accelerated ageing

Perform accelerated ageing of 10 (+2) test sheets of each of the four sample sets and 10 (+2) untreated

test sheets as described in ISO 5630-5:2008, Clause 4 to 9.2.

Test tubes selected for this study shall be perfectly gas-tight and large enough to accommodate paper

strips pre-cut for further measurements. It is required to perform aging for all samples simultaneously,

in the same laboratory oven, using one type of a glass tube for all samples.

NOTE To ensure perfect airtightness of testing tubes, the following steps could be taken:

— original tube caps supplied with glass tubes could be exchanged for caps made of material with higher

resistance to mechanical and thermal stresses (e.g. polyphenylsiloxane);

— sealing material – PTFE or silicone gaskets and o-rings should be avoided, fluoroelastomers are advisable

(e.g. Viton);

— tightening of the tube with the use of the dynamometric wrench equipped with a tube cap holder, to ensure

good repeatability of obtained sealing.
5.3.3.2 pH value

The pH value has to be measured in an aqueous extract as described in ISO 6588-1.

The average results and the average and the relative standard deviations should be given for treated

paper with and without ageing, and the results should be expressed to two significant digits.

The measured pH of the paper following deacidification has to be higher than 6,5 (before accelerated

ageing).

NOTE 1 The pH value of an aged sample will normally be lower compared to those of the non-aged sample. For

a given paper, ageing after deacidification should only lead to a small reduction of its pH value. It is possible that

the pH value measured after accelerated ageing will level out at around 6,5, even though an alkaline reserve is

still present. This is particularly true of the pH value on the paper surface which is usually one unit lower than

the pH value of the cold extract. Under these conditions, however, this kind of paper can still be described as

being neutral.

The pH value discussed here applies solely to the described test papers. If original papers are examined

as well, special agreements on an acceptable final pH value should be reached with the customer, as the

achieved pH value depends very much on the original composition of the paper.

NOTE 2 In addition to this measurement of aqueous extract pH value, measurements of surface pH value are

sometimes performed. The surface pH measurement is a faster method compared to extraction pH measurement

to judge the pH value of a paper. If applied correctly (see Reference [3]), surface pH measurements also allow on-

site measurements of original books and documents in libraries and archives and can also be used to follow the

stability of deacidification on a longer timescale. However, surface pH measurement has its limits. It works well

for acidic to neutral papers and also gives reasonable data until about pH 9. Usually, surface pH measurement has

been successfully used with immersion treatments. Surface pH measurement may fail to give reliable results when

larger amounts of alkaline reserve deposits are present at the paper surface and the solubility limit is reached.

5.3.3.3 Alkaline reserve

Determine the quantity of alkaline reserve of each of the four sample sets as described in ISO 10716.

For determination of the dry matter content, it is in deviation to ISO 10716 sufficient for the purpose of

this Technical Specification to weigh about 1 g to the nearest 0,001 g.
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The results, the average and the relative standard deviation should be given for treated paper with and

without ageing, and the results should be expressed to two significant digits.
The minimum alkaline reserve is 0,5 mass % expressed as MgCO .

NOTE Part of the total amount of alkaline substance applied to the paper by deacidification treatment is

chemically converted (“consumed”) by the neutralization reaction, and the remainder is the “alkaline reserve”.

The alkaline reserve ensures that the paper is resistant to acids acting upon it due to environmental influences

or degradation reactions occurring after the deacidification process.
5.3.3.4 Uniformity of deacidification

The uniformity of deacidification is measured by quantitative determination of the alkaline reserve,

expressed as mass % MgCO , at six different segments of a treated sample. Figure 1 shows the cutting

pattern for the segments.

Figure 1 — Segments for the determination of alkaline reserve for uniformity test

As one A5 sheet of test paper is not sufficient for analysing uniformity due to the limited sample

amount (for alkaline reserve 1 g of sample is required per data point), the measurement of the alkaline

reserve of the six treated paper samples is carried out as described in ISO 10716, with the following

amendments: Three A5 test paper sheets are cut into six rectangular, numbered segments of equal size

according to the pattern shown in Figure 1. Then, the three pieces with same numbers are put together,

divided into small pieces as described in ISO 10716, and the resulting pile is mixed well. About 1 g of

pieces is weighed and treated as described in ISO 10716.

Alkaline reserve measured for each section should be not less than 0,5 % by weight calculated as

MgCO equivalent. In addition, the relative standard deviation of the six individual measured values is

required to be less than 30 %. The lower the deviation calculated in this way, the better the uniformity

of deacidification.

NOTE 1 The results of these measurements describe the distribution of the added alkaline substance over the

entire surface area of the sheet of paper, not its homogeneous distribution across its thickness/cross section. For

the latter, no standardized routine methods are available.

NOTE 2 Some alternative methods exist which are able to address the uptake of deacidification reagent, in

most cases, the concentration of cations is analysed. However, these methods do not suffice as a full displacement

of alkaline reserve determination, as most of them are not fully comparable with the actual amount of alkaline

reserve. However, to estimate whether mass deacidification was homogeneous they can serve as alternative.

Potential methods are based on inductively coupled plasma optical spectrometry (ICP/OES) after the alkaline

reserve was extracted by acid from the paper segments, X-ray-Fluorescence scanning or FTIR/NIR and other

methods which reliably report the uptake of deacidification reagent.
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5.3.3.5 Degree of polymerisation

A pretreatment to remove the excess of alkaline reserve in the sample has to be performed as follows:

Disintegrate 1 g to 3 g of paper sample in a mixer for less than 30 s directly in 1,5 L, 0,1 M HCl at room

temperature (for 3 g of paper sample with 2 % alkaline reserve this corresponds to >200 fold excess of

acid when 1,5L are used). Rinse the sample thoroughly with water until washing water is neutral. Dry

sample at room conditions according to ISO 5351:2010, Clause 8. The sample preparation should be

adapted to the ingredients of the deacidification process.

NOTE 1 ISO 5351:2010, Clause 8 requires 10 g of material, but 1 g is sufficient for the DP sample preparation in

the present case.

Determine the degree of polymerisation by measuring the viscosity average with CED as described

in ISO 5351 before and after accelerated ageing. For determination of the dry matter content, it is in

deviation to ISO 5351 sufficient for the purpose of this Technical Specification to weigh about 1 g to the

nearest 0,001 g. The average results of the limiting viscosity number should be given for treated and

untreated papers with and without ageing, and the results should be expressed in millilitres per gram.

After accelerated ageing, the limiting viscosity number of the treated paper has to be high

...

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