ISO 8225:1987
(Main)Photography — Ammonia processed diazo photographic film — Specification for stability
Photography — Ammonia processed diazo photographic film — Specification for stability
Photographie — Film photographique diazoïque traité à l'ammoniac — Spécification pour la stabilité en conservation
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Standards Content (Sample)
IS0
INTERNATIONAL STANDARD
8225
First edition
1987-12-1 5
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXAYHAPOAHAR OPTAHMJA~MR Il0 CTAHAAPTM3AuMM
Photography - Ammonia processed diazo
photographic film - Specification for stability
Photographie - Film photographique diazoïque traité à i'arnrnoniac - Spécification pour la
stabifité en conservation
Reference number
IS0 8225 : 1987 (E)
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Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of
national standards bodies (IS0 member bodies). The work of preparing International
Standards is normally carried out through IS0 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, govern-
mental and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the IS0 Council. They are approved in accordance with IS0 procedures requiring at
least 75 % approval by the member bodies voting.
International Standard IS0 8225 was prepared by Technical Committee ISO/TC 42,
Photograph y.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
O International Organization for Standardization, 1987 O
Printed in Switzerland
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IS0 8225 : 1987 (E)
I N TE R N AT1 ON AL STA N DARD
Photography - Ammonia processed diazo
photographic film - Specification for stability
in both the visual and the actinic regions after storage. Such
O Introduction
films can be viewed directly or reprinted on to ultraviolet
Since 1930, great advances have been made in the use of
(UV)-sensitive materials. However, some diazo films are
photographic films for the preservation of records. The preser- manufactured which are not intended to be reprinted on to UV-
vation of film records by national, state, and municipal govern-
sensitive materials. Such films require only visual capabilities
ments, by banks, insurance companies, industry, and other after storage, and are designated as Class 6 films. Obviously,
enterprises, has been stimulated by a recognition of the resul-
both Class A and Class 6 films can fall into the medium-term
0
tant economies in storage space, organization, accessibility,
and long-term categories. The properties and processing re-
and ease of reproduction. The safe-keeping of pictorial film
quirements for Class A and Class B films are identical, with the
records having legal, scientific, industrial, medical, historical, exception of image stability tests after dark ageing and after
military, or other values has also become increasingly impor-
light fading.
tant.
Everyone concerned with the preservation of records on
photographic film should realize that specifying the chemical
The use of film for records having a long-term value
and physical characteristics of the material does not, by itself,
necessitated the development of International Standards speci-
assure satisfactory behaviour. It is also essential to provide the
fying the characteristics of film suitable for this purpose;
correct storage temperature and humidity and protection from
4331 and IS0 4332 specify the requirements for silver-
IS0
the hazards of fire, water, light and certain atmospheric
gelatin films which have archival keeping qualities. Archival
pollutants.
films have been defined as those suitable for the preservation of
records having permanent value. To date, only silver-gelatin
type film has been specified as meeting the requirements for ar-
1 Scope and field of application
chival records. Commercial diazo products do not fall within
this category.
1.1 This International Standard applies to
However, many users of photographic film are not interested in
- safety cellulose ester base and safety polyester base
permanence but in film usability after extended time periods.
Accordingly, two additional film categories were defined :
films which have an ammonia-processed diazo
"medium-term" and "long-term" film. The standardization of
photographic image;
0
these two additional film categories should increase the utility
- photographic film in which the image layer is a discrete
of this International Standard to a wider spectrum of interested
users. layer attached to a transparent support or in which the
image-forming chemicals are imbibed into a transparent
support;
Criteria for properties of medium-term and long-term diazo
films are based upon the dark ageing stability of diazo images.
-
Different dark incubation tests are specified for medium-term microfilm, roll film and sheet film.
and long-term film. All other property and processing re-
quirements for medium-term and long-term diazo films are
1.2 The photographic films covered by this International
identical.
Standard are those intended for medium-term and long-term
records.
It is recognized that diazo images may show density changes
after exposure to light. However, this International Standard
1.3 This International Standard characterizes only the in-
covers only films used as storage copies, not as work copies (as
herent keeping behaviour of the film covered. However, the
defined in annex BI. The light-fading requirements in this Inter-
suitability of a film record after extended storage depends on
national Standard ensure satisfactory behaviour for storage
both the inherent ageing characteristics of the film and the
copies which are not intended to be subjected to frequent light
original image quality. The latter is discussed in annex A.
exposure.
In addition to the characterization of films with respect to their 1.4 This International Standard applies only to photographic
expected storage life, diazo films are also separated into two diazo film intended and used as medium-term and long-term
classifications (A and B) ; these classes being dependent upon storage copies. It does not apply to diazo film records intended
and used as "work or "use" copies as discussed in annex B.
their intended use. Class A films are those which have density
1
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IS0 8225 : 1987 (E)
film base: The plastic support for the image layers or
3.6
2 References
image-forming chemicals, see annex C.
IS0 5, Photography - Density measurements -
3.7 safety cellulose ester base: A film base composed
Part I: Terms, symbols, and notation.
mainly of cellulose esters of acetic, propionic, or butyric acids,
or mixtures thereof.
Part 2: Geometric conditions for transmission density.
Part 3: Spectral conditions.
3.8 safety poly(ethylene terephthalate) base: A film base
composed mainly of a polymer of ethylene glycol and
IS0 1184, Plastics - Determination of tensile properties of
terephthalic acid.
films.
3.9 safety photographic film: Film that meets the
IS0 4331, Photography - Processed photographic film for
specifications with respect to hazard from fire as defined in
archival records - Silver-gelatin type on cellulose ester base -
IS0 7830.
Specifications.
IS0 4332, Photography - Processed photographic film for
3.10 medium-term storage : Those storage conditions
archival records - Silver-gelatin type on poly(eth ylene
suitable for ensuring a minimum useful life of 10 years for
terephthalate) base - Specifications.
medium-term films.
IS0 5466, Photography - Practice for the storage of processed
3.11 optimum storage: Those storage conditions suitable
safety photographic film.
for the preservation of photographic film having permanent
value.
IS0 5626, Paper - Determination of folding endurance.
NOTE - Optimum storage conditions will prolong the useful life of
IS0 6Oï7, Photography - Determination of brittleness of
both archival and non-archival films.
photographic film - Wedge britîleness test.
3.12 transmission density: The radiant energy-absorbing
IS0 7830, Photography - Safety photographic films other
quality of a photographic material, expressed as the co-
than motion-picture films - Material specifications.
logarithm of the transmittance factor determined for specified
geometric and spectral conditions (see IS0 5).
3 Definitions
3.13 visual transmission density: A density measurement
meeting spectral requirements specified in IS0 5-3 for visual
For the purpose of this International Standard the following
density.
definitions apply.
NOTE - The geometric conditions of measurement should also be
described.
3.1 medium-term film: A photographic film which is
suitable for the preservation of records for a minimum of
3.14 printing transmission density: A density measure-
10 years when stored under "medium-term" conditions, pro-
ment of a spectrally non-selective film which will produce the
viding the original images are of suitable quality.
same response on the print material as the film measured (see
IS0 5-31. The contact printing density of a film specimen is
3.2 long-term film: A photographic film which is suitable
equal to the transmission density of a spectrally non selective
for the preservation of records for a minimum of one hundred
neutral modulator when they both produce the same response
years when stored under "optimum" conditions, providing the
on the print material when contact printed together.
original images are of suitable quality.
4 Physical requirements
3.3 archival film: A photographic film which is suitable for
the preservation of records having permanent value when
stored under "optimum" conditions and providing the original 4.1 Film base type
images are of suitable quality.
The base used for diazo film shall be of a safety cellulose ester
type or safety poly(ethy1ene terephthalate) type and can be
NOTE - Films suitable for archival records are specified in IS0 4331
identified by the method specified in 7.1.
and IS0 4332.
4.2 Viscosity retention
3.4 class A films: Films which are usable both visually and
for printing on to ultraviolet-sensitive materials.
The relative viscosity of a solution of film base obtained from
processed film shall not show a loss which exceeds 5 % as the
result of accelerated ageing of the processed film. The ac-
3.5 class B film: Films which are usable visually but do not
have any density requirements for printing on to ultraviolet- celerated ageing shall be accomplished as specified in 6.2 and
sensitive materials. the viscosity determined as specified in 7.2.
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IS0 8225 : 1987 (E)
4.5 Layer adhesion
4.3 Safety requirements
The film shall meet the requirements of the safety film specified
4.5.1 Tape-stripping emulsion adhesion
in IS0 7830.
The processed film shall not show any removal of the pro-
4.4 Base physical property loss cessed image or image layer when tested before and after ac-
celerated ageing. Accelerated ageing shall be accomplished as
specified in 6.2, and the emulsion adhesion test shall be per-
4.4.1 Cellulose ester base film
formed as specified in 7.4 (see also annex CI.
Processed film shall withstand the number of double MIT folds
1 of table 1 when tested as specified in 7.3. The
specified in line
4.5.2 Humidity-cycling emulsion adhesion
loss in folding endurance after accelerated ageing, as specified
in 6.2, shall not exceed the percentage specified in line 2 of
The processed image layer shall not show separation or crack-
table 1.1)
ing which would impair its intended use when tested as
specified in 7.5 (see also annex Cl.
Table 1 - Limits for flexibility and flexibility
4.6 Blocking
loss of cellulose ester base film
Processed film shall show no evidence of blocking (sticking),
under 0,13 to
Characteristic
delamination, or surface damage when tested before and after
0,13 mm
accelerated ageing, as specified in 6.2. Blocking shall be tested
1 Unheated film
as specified in 7.6.
Minimum permissible average
number of double MIT folds A slight sticking of the film samples which does not result in
physical damage or a change in the gloss of the surface shall be
2 Film after accelerated ageing
acceptable.
Maximum permissible average
25 % 35 %
loss in folds
4.7 Binder stability
Processed film shall not exceed a 1 mm increase in brittleness
4.4.2 Poly(ethy1ene terephthalate) base film after accelerated ageing as specified in 6.2. Brittleness shall be
determined at 50 % relative humidity in accordance with
Processed film shall have a tensile strength and elongation at IS0 6077.
break as specified in line 1 of table 2 when tested as specified in
7.3. The loss in tensile properties after accelerated ageing, as
Films shall be tested in either low-density or high-density areas.
specified in 6.2, shall not exceed the percentage specified in
line 2 of table 2.
4.8 Thermal sticking
Processed film shall show no evidence of blocking (sticking),
Table 2 - Limits for tensile properties and tensile
0
delamination or surface damage at high temperatures when
properties loss of polyiethylene terephthalate) base film
tested before and after accelerated ageing as specified in 6.2.
Thermal sticking shall be tested as specified in 7.7.
Tensile
Elongation
strength
Characteristic
at break
at break
A slight sticking of film to glass which does not result in
physical damage shall be acceptable.
1 Unheated film
Minimum permissible
138 MPa* 75 %
tensile properties
5 Image requirements
2 Film after accelerated
ageing
5.1 Proper development
Maximum permissible loss
10 % 10%
in tensile properties
Processed film shall not show a visual diffuse transmission den-
sity decrease greater than 30 % when tested as specified in 8.2.
* 1 MPa = 106N/m*
The increase in the limits for percentage fold loss with increase in film thickness is necessary because the test is Ïess precise when the number of
1)
folds is small.
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IS0 8225 : 1987 (E)
at 20 % relative humidity. This relative humidity can be obtain-
5.2 image stability - Light fading
ed by keeping a saturated solution of potassium acetate in
water at the bottom of the jar.') Care shall be exercised to
Low-density and high-density patches of the processed film
light exposure apparatus as described in 8.3. ensure that the saturated solution contains an excess of
shall be tested in a
undissolved crystals at 100 OC. The undissolved crystals shall
After testing, the low-density patches shall have a diffuse den-
sity of 0,4 or less, and the difference between the high-density be completely covered by the saturated salt solution and the
and low-density patches shall be 0,8 or greater (see table 3). surface area of the solution should be as large as practical. The
These density requirements shall apply to both visual and jar and the salt solution shall be maintained at 100 OC for at
least 20 h prior to use to ensure adequate equilibrium.
type 2 printing densities for class A films and to visual density
only for class B films (see annex DI.
Alternatively, exposure to these temperatures and humidity
conditions may be provided by means of a conditioning air
5.3 image stability - Dark ageing
cabinet. The samples shall be suspended to keep them
separated from each other. No other materials shall be in the
Low-density and high-density patches of the processed film
same environment as the test samples during the heating
shall be incubated as specified in 8.4 using the conditions
period.
specified for either medium-term or long-term films. After in-
cubation, the low-density patch shall have a diffuse density of
In subsequent sub-clauses, specimens subjected to these
0,4 or less, and the difference between the high-density and
accelerated ageing conditions are designated "heated
low-density patches shall be 0,8 or greater (see table 3). These
specimens".
density requirements shall apply to both visual and type 2
printing densities for class A films and to visual density only for
class B films.
7 Physical test methods
Table 3 - Limits for image diffuse density
change after accelerated testing*
7.1 identification of film base
and long-term film
All emulsion, backing and sublayers shall be removed from a
Original diazo density levels specimen of the unknown film by scraping. A sample of the
base material shall then be prepared by scuffing the surface
Low density 0,lO 4 0,05
with a suitable tool to produce a very fine powder. This powder
High density 1,2 1: 0,l
shall be mixed in a mortar with about 100 times its mass of
Final diazo density levels**
potassium bromide previously ground to about 75 pm. A strip
Low density 6 0.4
or pellet shall be prepared [il. An infra-red absorption curve
High density - Low density 2 0.8
shall be obtained from this pellet by means of an infra-red
absorption spectrometer. The identity of the unknown base
can be established by comparison with curves for known
polymers 121.
7.2 Relative viscosity test
Measurements shall be made on two unheated specimens of
6 Accelerated ageing
processed film having the same average photographic density.
The emulsion and any backing layers shall be removed by
6.1 General
scraping before proceeding with the relative viscosity deter-
mination. Each sample of base without coatings shall have a
Processed film shall be subjected to the following accelerated
mass of 1,OO g. Each specimen shall be treated as follows:
it meets the re-
ageing conditions when determining whether
quirements specified in clause 4 for viscosity retention, base
If the film base is a cellulose ester as determined by 7.1, each
physical property retention, tape-stripping emulsion adhesion,
specimen shall be immersed in a separate 100 ml one mark volu-
blocking, binder stability and thermal sticking.
metric flask containing approximately 95 ml of a mixture of
90 %(m/rn) methvlene chloride and 10 % (rn/m) methanol.
6.2 Accelerated ageing conditions
WARNING - Methylene chloride is toxic by inhalation,
The processed test samples shall be mounted in a sample rack Do not breathe
contact with skin and if swallowed.
SO that they are freely exposed to the surrounding air. The rack vapours. Avoid contact with skin.
shall then be placed in a glass laboratory desiccator jar. The jar
shall be heated in a forced-air circulating oven for 72 h at
The base may be dissolved by repeated shaking for 1 to 2 h or
100 f 2 OC. The atmosphere within the jar shall be maintained by allowing the mixture to stand overnight.
1) The relative humidity is based on the nominal vapour pressure of the salt solution but the relative humidity tolerances cannot be specified.
4
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IS0 8225 : 1987 (E)
room or a conditioning air cabinet. The specimens shall be sup-
If the film base is poly(ethy1ene terephthalate) as determined
ported in such a way as to permit free circulation of air around
by 7.1, it can be dissolved in approximately 95 ml of a mixture
the film and the linear air velocity shall be at least 15 cmls.
of 60 % (rnlrn) phenol and 40 % (rnlrn) chlorobenzene by
mass.
7.3.3 Procedure
WARNING - Phenol chlorobenzene mixture causes
severe burns, is toxic by inhalation, contact with skin and
The film specimens shall not be removed from the conditioning
if swallowed. Do not breathe vapours. After contact with
atmosphere for testing. The unheated and heated specimens
skin, wash immediately with plenty of water. Do not
shall be tested alternately, and the averages shall be calculated
pipette by mouth.
separately.
Preoare the mixture of phenol and chlorobenzene by stirring
The cellulose ester base films shall be tested for folding en-
the molten phenol into the chlorobenzene. Use hot solutions in
durance using the MIT folding tester as described in IS0 5626.
a fume cupboard.
The poly(ethy1ene terephthalate) base films shall be tested for
tensile strength and percentage elongation at break as specified
The base may be dissolved by repeated shakings or strirring for
in IS0 1184. The thickness of each specimen shall be measured
15 min in an oil bath at 140 f 1 OC.
to the nearest 0,002 mm and the width to the nearest 0,l mm.
Immerse the flasks containing the dissolved film base in a water
bath maintained at 25 I 1 OC until temperature equilibrium has 7.4 Tape-stripping adhesion test
0
been reached. Add solvent to adjust the volume of the solution
to 100 ml, and thoroughly mix the contents. Transfer a portion 7.4.1 Specimen preparation
of the liquid, by filtrationl) if necessary, to an Ostwald pipette
in a Although the dimensions of the processed film specimen are
or an equally suitable capillary viscometer immersed
not critical, one dimension shall be at least 15 cm. Measure-
constant-temperature bath at the same temperature.
ments shall be made on two specimens of unheated, processed
film and on two heated specimens.
WARNING - These solutions are toxic by inhalation,
contact with skin and if swallowed. Use a water pump or
vacuum pump to draw these solutions into pipettes.
7.4.2 Conditioning
The pipette chosen shall have a flow time between 70 and 110 s
Specimens shall be conditioned as specified in 7.3.2.
for the solvent. The volume taken shall be sufficient to fill half
the lower bulb of the pipette. Measure the time of flow of the
7.4.3 Procedure
solution through the capillary of the pipette to the nearest 0,2 s.
Repeat the measurement for the same volume of the pure sol-
The film specimens shall not be removed from the conditioning
vent. Make three readings for each portion. The relative vis-
atmosphere for testing. Apply a strip of pressure-sensitive,
cosity is the ratio of the average flow time of the solution to
plastic-base, adhesive tape about 15 cm long to the surface of
that of the solvent. Duplicate determinations shall be made on
the processed film. Press the tape down with thumb pressure
both the unheated and heated specimens and the averages
to ensure adequate contact, leaving enough tape at one end to
shall be calculated separately.
grasp. No portion of the tape shall extend beyond the edges of
the film or cover areas of the film perforations. While holding
the film firmly on a flat surface rapidly remove the tape from the
7.3 Base physical property loss
film surface by peeling the tape back on itself and pulling the
end so that it is removed from the film at an angle of approxi-
7.3.1 Sample preparation
mately Iwo. Removal by the tape of any portion of the surface
layer on any of the specimens shall be considered failure.
Processed film in 16 mm form may be tested in this width. Films
in other sizes shall be cut 15 to 16 mm wide and at least 12 cm
The results of the tape-stripping test may be very dependent
long, using a sharp tool which does not nick the edges of the
upon the adhesive tape used if the bonding force between it
sample. Ten specimens are required for unheated film and ten
and the particular film surface under test is not sufficiently
specimens for film heated as specified in 6.2. The unheated and
high. For this reason, a minimum bonding force is specified for
heated specimens shall be cut alternately and continuously
this test. Determine this bonding force by applying the
a single piece of film.
from
adhesive tape to the film surface, in the same manner as
specified in the tape-stripping test, and peeling it back rapidly
from the film surface at an angle of approximately 180O.
7.3.2 Conditioning
Measure the peel-back force required to separate the tape from
the film by use of a strain gauge or a maximum-reading spring
All specimens, both unheated and heated, shall be Conditioned
scale. A bonding force of at least 4 N per centimetre of tape
at 23 i 2 OC and (50 f 2) % relative humidity for at least 15 h.
width is required.
This may be accomplished by means of an air-conditioned
Filtration has to be rapid to avoid solvent loss. This may be accomplished by filtering through a porous glass-wool pad.
1)
5
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IS0 8225 : 1987 (E)
surface of one specimen is against the back surface of the adja-
7.5 Humidity-cycling adhesion test
cent one. Place the stack under a uniform pressure of 35 kPa.
This may be accomplished by placing a weight on the film
7.5.1 Specimen preparation
stack, the dimensions of the weight being greater than those of
the film specimens. Replace the jar containing the weighted
A specimen 5 cm square or 5 cm by the film width is conve-
stack in the forced-air circulating oven for 3 days at 40 OC.
nient, but the dimensions are not critical. Two specimens of
Alternatively, exposure to the conditions of temperature and
processed film shall be selected from a high-density area.
humidity may be provided by means of air-conditioning
cabinets or rooms.
7.5.2 Procedure
Remove the film stack from the oven and allow to cool. Then
remove individually the film specimens from the stack and
Mount the specimens in a rack and place in a glass laboratory
observe for evidence of film blocking (sticking).
desiccator jar SO that they are freely exposed to the at-
mosphere. Place the jar for 8 h in a forced-air circulating oven
maintained at 50 f 2 OC. The atmosphere within the jar shall be
7.7 Thermal sticking test
96 % relative humidity, which can be obtained by
maintained at
keeping a saturated solution of potassium sulfate in water [3] in
Measurements shall be made on two unheated specimens of
the bottom of the jar.1) After 8 h, place the rack for 16 h in a se-
processed film and on two heated specimens as specified in
cond desiccator jar in the same oven. The atmosphere within
6.2. A specimen 5 cm square is convenient, but the dimensions
this second jar shall be maintained at 11 % relative humidity,
are not critical.
which can be obtained by keeping a saturated solution of
lithium chloride in water 131 in the bottom of the jar.') The
Place each specimen between two smooth uncoated glass
precautions specified in 6.2 shall be taken to ensure that the
plates that have dimensions slightly larger than the film. Place
proper humidity is obtained.
the film under a uniform pressure of 35 kPa. This may be ac-
complished by placing a weight on the upper glass plate, the
Time periods of 8 h at the high humidity and 16 h at the low
dimensions of the weight being greater than that of the film
humidity shall constitute one cycle.2) Subject the film to 12
sample. Place each glass-plate film sandwich into a forced-air
humidity cycles, after which remove from the rack and examine
circulating oven for 1 h at 65 f 2 OC.
the emulsion layer for peeling, flaking, or cracking.3) Examine
the film under the same magnification and lighting conditions
Remove the glass-plate film sandwich from the oven and allow
as normal for product use. During a weekend interruption in the
to cool. Separate the glass plates from the film and observe for
cycling procedure, the film shall be kept at 50 f 2 OC and 11 %
evidence of blocking (sticking), film delamination, and surface
relative humidity.
damage.
7.6 Blocking test
8 Image test methods
At least five specimens of processed film shall be conditioned
to 62 % relative humidity at 40 _+ 2 OC. A specimen size of 5 cm
8.1 Densitometry
square is convenient where the size of the film permits, but the
dimensions are not critical, provided all specimens are of Image density shall be measured as specified in 8.1 .I and 8.1.2.
uniform size.
8.1.1 Visual density
Place the specimens in a glass laboratory desiccator jar so that
they are freely exposed to the required conditioning at-
IS0 standard visual diffuse transmission density shall be
mosphere for at least 15 h. Put the jar containing the samples
measured using a densitometer with the geometric require-
40 f 2 OC. A relative
into a forced-air circulating oven at
ments specified in IS0 5-2 and the spectral requirements
humidity of approximately 62 % can be obtained by keeping a
specified in IS0 5-3.
saturated solution of sodium nitrite 141 in water at the bottom of
the jar. The precautions specified in 6.2 shall be taken to ensure
8.1.2 Printing density
that the proper humidity is obtained.
After moisture equilibrium is attained, remove the jar from the IS0 type 2 printing transmission density shall be determined as
oven without removing the specimens from the jar, and stack specified in IS0 5-2 and IS0 5-3 and designated as DT (90"
at least five specimens on a smooth surface so that the image opal; S, : < IOo; s2).
1) The relative humidity is based on the nominal vapour pressure of the salt solution but the relative humidity tolerances cannot be specified.
2) This can be most easily accomplished by placing the samples in the 96 % relative humidity jar in the morning and the 11 % jar in the evening.
3) Films may sometimes exhibit small pinholes in the image after processing. These can be caused by dirt or dust particles on the emulsion surface at
the time raw film is exposed and should not be confused with holes or cracks in the emulsion layer. The existence of such pinholes in the image prior
SO that their presence does not lead to false interpretation of an adhesion weakness.
to humidity cycling should be noted
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IS0 8225 : 1987 (E)
8.4 Image stability - Dark agein
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