SIST EN 46-1:2016
(Main)Wood preservatives - Determination of the preventive action against recently hatched larvae of Hylotrupes bajulus (Linnaeus) - Part 1: Application by surface treatment (laboratory method)
Wood preservatives - Determination of the preventive action against recently hatched larvae of Hylotrupes bajulus (Linnaeus) - Part 1: Application by surface treatment (laboratory method)
This European Standard specifies a method for the determination of the preventive action of a wood preservative against recently hatched larvae of Hylotrupes bajulus (Linnaeus) when the preservative is applied as a surface treatment to wood. This method is applicable to: - water-insoluble chemicals which are being studied as active insecticides; - organic formulations, as supplied or as prepared in the laboratory by dilution of concentrates; - organic water-dispersible formulations as supplied or as prepared in the laboratory by dilution of concentrates; and - water-soluble materials, for example salts. The method is applicable whether or not the test specimens have been subjected to appropriate ageing procedures.
Holzschutzmittel - Bestimmung der vorbeugenden Wirkung gegenüber frisch geschlüpften Larven von Hylotrupes bajulus (Linnaeus) - Teil 1: Anwendung durch Oberflächenverfahren (Laboratoriumsverfahren)
Diese Europäische Norm legt ein Verfahren zur Bestimmung der vorbeugenden Wirkung eines Holzschutzmittels gegenüber frisch geschlüpften Larven (Eilarven) von Hylotrupes bajulus (Linnaeus) fest, wobei das Holzschutzmittel zur Oberflächenbehandlung des Holzes verwendet wird.
Das Verfahren gilt für:
- wasserunlösliche Chemikalien, die als wirksame Insektizide untersucht werden;
- organische Formulierungen im Anlieferungszustand oder in Form von im Laboratorium hergestellten Verdünnungen von Konzentraten;
- organische, in Wasser dispergierbare Formulierungen im Anlieferungszustand oder in Form von im Laboratorium hergestellten Verdünnungen von Konzentraten; und
- wasserlösliche Stoffe, zum Beispiel Salze.
Das Verfahren gilt unabhängig davon, ob die Prüfkörper einer angemessenen Alterungsbeanspruchung ausgesetzt wurden oder nicht.
Produits de préservation des bois - Détermination de l'action préventice contre les larves récemment écloses d'Hylotrupes bajulus (Linnaeus) - Partie 1 : Application par traitement de surfave (Méthode de laboratoire)
La présente Norme européenne prescrit une méthode de détermination de l’action préventive d'un produit de préservation du bois contre les larves récemment écloses d’Hylotrupes bajulus (Linnaeus) lorsque le produit de préservation est appliqué au bois par un traitement de surface.
La présente méthode est applicable :
- aux produits chimiques non hydrosolubles étudiés en tant que matières actives insecticides ;
- aux formules organiques telles qu'elles sont fournies ou préparées en laboratoire par dilution de concentrés ;
- aux formules organiques hydrodispersables telles qu'elles sont fournies ou préparées en laboratoire par dilution de concentrés ; et
- aux produits solubles dans l’eau, des sels par exemple.
Cette méthode s’applique à des éprouvettes ayant subi ou non des épreuves de vieillissement appropriées.
Biocidni proizvodi za zaščito lesa - Ugotavljanje preventivnega delovanja proti hišnemu kozličku Hylotrupes bajulus (Linnaeus) - 1. del: Ugotavljanje učinkovitosti proti ličinkam (laboratorijska metoda)
Ta evropski standard določa metodo za ugotavljanje preventivnega delovanja zaščitnega
sredstva za les proti hišnemu kozličku Hylotrupes bajulus (Linnaeus), ko je zaščitno sredstvo
uporabljeno v sklopu površinske obdelave lesa.
Ta metoda se uporablja za:
– v vodi netopne kemikalije, ki se preučujejo kot aktivni insekticidi;
– organske formulacije, ki so dobavljene ali pripravljene v laboratoriju z redčenjem koncentratov;
– organske formulacije, ki se razpršijo v vodi in so dobavljene ali pripravljene v laboratoriju z redčenjem
koncentratov ter
– v vodi topne materiale, na primer sol.
Metoda se uporablja ne glede na to, ali so preskušanci izpostavljeni ustreznim postopkom staranja ali ne.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Holzschutzmittel - Bestimmung der vorbeugenden Wirkung gegenüber frisch geschlüpften Larven von Hylotrupes bajulus (Linnaeus) - Teil 1: Anwendung durch Oberflächenverfahren (Laboratoriumsverfahren)Produits de préservation des bois - Détermination de l'action préventice contre les larves récemment écloses d'Hylotrupes bajulus (Linnaeus) - Partie 1 : Application par traitement de surfave (Méthode de laboratoire)Wood preservatives - Determination of the preventive action against recently hatched larvae of Hylotrupes bajulus (Linnaeus) - Part 1: Application by surface treatment (laboratory method)71.100.50Wood-protecting chemicalsICS:Ta slovenski standard je istoveten z:EN 46-1:2016SIST EN 46-1:2016en,fr,de01-september-2016SIST EN 46-1:2016SLOVENSKI
STANDARDSIST EN 46-1:20101DGRPHãþD
SIST EN 46-1:2016
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 46-1
June
t r s x ICS
y sä s r rä w r Supersedes EN
v xæ sã t r r {English Version
Wood preservatives æ Determination of the preventive action against recently hatched larvae of Hylotrupes Produits de préservation du bois æ Détermination de l 5action préventive contre les larves récemment écloses
Holzschutzmittel æ Bestimmung der vorbeugenden Wirkung gegenüber frisch geschlüpften Larven von durch Oberflächenverfahren This European Standard was approved by CEN on
w January
t r s yä
egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä
translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä
CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels
9
t r s x CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
v xæ sã t r s x ESIST EN 46-1:2016
EN 46-1:2016 (E) 2 Contents Page European foreword . 4 Introduction . 5 1 Scope . 6 2 Normative references . 6 3 Terms and definitions . 6 4 Principle . 7 5 Test materials . 7 5.1 Biological material . 7 5.2 Products and reagents . 7 5.3 Apparatus . 7 6 Sampling . 8 7 Test specimens . 8 7.1 Species of wood . 8 7.2 Wood quality . 9 7.3 Provision of test specimens . 9 7.4 Dimensions of test specimens . 9 7.5 Number of test specimens . 9 8 Procedure. 10 8.1 Preparation of the test specimens . 10 8.1.1 Conditioning of the test specimens prior to sealing . 10 8.1.2 Sealing of the transverse faces . 10 8.1.3 Treatment of the test specimens . 10 8.1.4 Drying and conditioning of the test specimens after treatment . 12 8.2 Exposure of the test specimens to the insects . 12 8.3 Conditions and duration of the test . 13 8.4 Examination of the test specimens . 13 8.4.1 Examination . 13 8.4.2 Validity of the test . 14 9 Expression of results . 14 9.1 Evaluation of attack . 14 9.2 Toxic values . 14 10 Test report . 15 Annex A (informative)
Example of a test report . 17 Annex B (informative)
Technique for culturing Hylotrupes bajulus (Linnaeus) . 19 B.1 General . 19 B.2 Obtaining parent beetles . 19 B.3 Mating . 19 B.4 Egg-Iaying . 19 SIST EN 46-1:2016
EN 46-1:2016 (E) 3 B.5 Hatching of eggs . 20 B.6 Larval development . 20 B.7 Enemies and parasites . 21 Annex C (informative)
Differentiation of heartwood and sapwood in Pinus species . 22 C.1 Principle . 22 C.2 Reagents . 22 C.3 Apparatus . 22 C.4 Procedure . 22 Annex D (informative)
Environmental, health and safety precautions within chemical/biological laboratory . 23 Annex E (normative)
Slow acting and deferred effect formulations – Extending the test duration . 24 Bibliography . 26
SIST EN 46-1:2016
EN 46-1:2016 (E) 4 European foreword This document (EN 46-1:2016) has been prepared by Technical Committee CEN/TC 38 “Durability of wood and wood-based products”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 2016, and conflicting national standards shall be withdrawn at the latest by December 2016. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 46-1:2009. Significant technical differences between this document and EN 46-1:2009 are as follows: a)
introduction of new harmonized specifications for wood quality; b)
option to omit control test specimens treated with the solvent or diluents only when the solvent or diluents is water of drinking quality; c)
determination of validity of the test by using an X-ray apparatus added in 8.4.2. The standard EN 46 is composed of two parts: — EN 46-1, Wood preservatives
— EN 46-2, Wood preservatives
hatched
EN 46 consists of two parts to enable preventive action of wood preservatives, against recently hatched larvae of Hylotrupes bajulus, which are intended to be applied by surface treatment; Part 1 is required to determine the larvicidial effect of preservatives and Part 2 is required to determine the ovicidal action of the preservatives after egg-laying of young females. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 46-1:2016
EN 46-1:2016 (E) 5 Introduction This European Standard describes a laboratory method of testing which gives a basis for the assessment of the preventive action of a wood preservative, when applied as a surface treatment, against recently hatched larvae of Hylotrupes bajulusá whereas the method for determining the toxic values against Hylotrupes bajulus (EN 47) provides a means of checking whether a preservative prevents attack by these larvae and prevents their survival within totally impregnated wood. This method makes it possible to determine whether recently hatched larvae are capable of boring through the treated surface of a susceptible wood species and of surviving in the untreated part of the test specimen. For this purpose, the procedure seeks to reproduce normal egg-laying conditions existing in cracks in wood, which provide the principal egg-laying sites. It takes account of the fact that, if larvae pass through the treated surface, they will then tunnel in the direction of the least protected regions of the wood. This laboratory method provides one criterion by which the value of a preservative can be assessed. In making this assessment, the methods by which the preservative may be applied should be taken into account. This test is of particular interest when applied to test specimens which have been subjected to an ageing procedure. It is further recommended that results from this test should be supplemented by those from other appropriate tests and, above all, by practical experience. When products which are very active at low concentrations are used it is very important to take suitable precautions to isolate and separate, as far as possible, operations involving chemical products, other products, treated wood, laboratory apparatus and clothing. Suitable precautions should include the use of separate rooms, areas within rooms, extraction facilities, conditioning chambers and special training for personnel (see also Annex D for environmental, health and safety precautions). SIST EN 46-1:2016
EN 46-1:2016 (E) 6 1 Scope This European Standard specifies a method for the determination of the preventive action of a wood preservative against recently hatched larvae of Hylotrupes bajulus (Linnaeus) when the preservative is applied as a surface treatment to wood. This method is applicable to: — water-insoluble chemicals which are being studied as active insecticides; — organic formulations, as supplied or as prepared in the laboratory by dilution of concentrates; — organic water-dispersible formulations as supplied or as prepared in the laboratory by dilution of concentrates; and — water-soluble materials, for example salts. The method is applicable whether or not the test specimens have been subjected to appropriate ageing procedures. 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. EN 73, Wood preservatives — Accelerated ageing of treated wood prior to biological testing — Evaporative ageing procedure EN 84, Wood preservatives — Accelerated ageing of treated wood prior to biological testing — Leaching procedure EN ISO 3696, Water for analytical laboratory use —
3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 representative sample sample having its physical and/or chemical characteristics identical to the volumetric average characteristics of the total volume being sampled [SOURCE: EN 1001-2:2005, 4.71] 3.2 supplier sponsor of the test (person or company providing the sample of wood preservative to be tested) Note 1 to entry: Adapted from EN 1001–2:2005, 4.83. SIST EN 46-1:2016
EN 46-1:2016 (E) 7 4 Principle Depending on the test being carried out either: — on a set of test specimens of a susceptible wood species that is surface treated with a solution of the preservative; or — if toxic values are to be determined, on several sets of test specimens of a susceptible wood species that are surface treated with a series of solutions in which the concentration of preservative is ranged in a given progression. The treated test specimens are exposed to recently hatched larvae of Hylotrupes bajulusä The resulting attack is observed and compared with those in untreated control test specimens. If the preservative has been prepared in the laboratory by dilution of a concentrate or by dissolution of a solid, the resulting attack is also compared to that in solvent or diluent treated control test specimens. 5 Test materials 5.1 Biological material 5.1.1 Hylotrupes bajulus (Linnaeus) larvae, within three days of hatching. 5.1.2 Source of larvae. Obtain the larvae from cultures reared, e.g. as described in Annex B. 5.1.3 Provision of larvae. Collect larvae from eggs laid by different females. 5.1.4 Choice of larvae. Use a mixed batch of these larvae for the test. Use ten larvae per treated test specimen or control test specimen. 5.2 Products and reagents 5.2.1 Paraffin wax, for fixing the glass plate and for sealing the end faces of test specimens to be treated with solutions in all cases in which water is the continuous phase. NOTE Paraffin wax with a setting point of 52 °C to 54 °C has been found to be suitable. 5.2.2 Gelatin, for sealing the end faces of test specimens to be treated with solutions in which an organic solvent is the continuous phase. 5.2.3 Water, complying with grade 3 of EN ISO 3696. 5.2.4 Solvent or diluent, a volatile liquid that will dissolve or dilute the preservative but does not leave a residue in the wood at the end of the post-treatment conditioning period that has a toxic effect on the insects. CAUTION — Do not use benzene or other solvents which pose a health risk. 5.3 Apparatus 5.3.1 Culturing chamber, with air circulation, and controlled at (28 ± 2) °C and at a relative humidity of (70 ± 5) %. 5.3.2 Conditioning chamber, well ventilated and controlled at (20 ± 2) °C and at a relative humidity of (65 ± 5) %. SIST EN 46-1:2016
EN 46-1:2016 (E) 8 The conditioning of test specimens may be carried out in the laboratory work area (see 5.3.3) provided that this has the conditions specified for the conditioning chamber (see 5.3.2). 5.3.3 Laboratory work area, well ventilated, where treatment of the test specimens is carried out. CAUTION — It is essential to follow safety procedures for handling flammable and toxic materials. Avoid excessive exposure of operators to solvents or their vapours. 5.3.4 Testing chamber, ventilated and air conditioned, controlled at (22 ± 2) °C and at a relative humidity of (70 ± 5) %. 5.3.5 Treatment vessels of a material that does not react with the preservative under test, for example of glass for organic products and of polyethylene for salts containing fluorine. 5.3.6 Weights, to provide ballast for the test specimens. The weights shall not react with any materials with which they come into contact during the test. 5.3.7 Safety equipment and protective clothing, appropriate for the test product and the test solvent, to ensure the safety of the operator. 5.3.8 Glass plates, (48 ± 1) mm long and (25 ± 1) mm wide, intended to provide a lateral slit on the test specimens. 5.3.9 Ordinary laboratory equipment, including a balance capable of weighing to an accuracy of 0,01 g. 5.3.10 Protective gloves 5.3.11 X-ray apparatus, (optional) with tungsten target and beryllium window, with voltage and current continuously variable in the ranges: — voltage: 10 kV to 50 kV; — current: 0 mA to 15 mA. 6 Sampling The sample of preservative shall be representative of the product to be tested. Samples shall be stored and handled in accordance with any written recommendations from the supplier. For the sampling of preservatives from bulk supplies, the procedure given in EN 212 should be used. 7 Test specimens 7.1 Species of wood The reference species is Scots pine (Pinus sylvestris Linnaeus)1). Additional tests may be carried out using other species but, if so, this should be stated in the test report.
1) In southern European countries the pine species most frequently infested by Hylotrupes bajulus may be used as an alternative, provided that the suitability of the species for use in the tests specified in this document has been demonstrated in all aspects (development of larvae, resistance to impregnation, etc.). SIST EN 46-1:2016
EN 46-1:2016 (E) 9 7.2 Wood quality The wood shall be free from visible cracks, stain, decay, insect damage and other defects. The wood shall not have been water-stored, floated, chemically treated or steamed. The wood shall originate from trees preferably felled in winter. The trees shall be cut immediately after felling and the timber rapidly air-dried or kiln dried at temperatures below 60 °C. The wood shall not have been stored for more than five years. The wood shall be exclusively sapwood containing little resin and having between 2,5 annual rings per 10 mm and eight annual rings per 10 mm. The proportion of latewood in the annual rings shall not exceed 30 % of the whole. It is recommended to use test specimens of similar growth rate within a single test. 7.3 Provision of test specimens2) Prepare planed strips having a cross-section of (25 ± 0,5) mm × (15 ± 0,5) mm removing a minimum of 2 mm from any faces exposed during drying. The longitudinal faces shall be parallel to the direction of the grain. The annual rings shall have a contact angle of 45° ± 15° to the broad faces. Make transverse cuts, neatly to give sharp edges and a fine-sawn finish to the end-grain surfaces, to give test specimens (50 ± 0,5) mm long. The test specimens shall originate from a minimum of three trees or shall be taken at random from a stock originally of more than 500 test specimens. 7.4 Dimensions of test specimens The dimensions of each test specimen after reaching equilibrium in the conditioning chamber (5.3.2) shall be (50 ± 0,5) mm × (25 ± 0,5) mm × (15 ± 0,5) mm. Mark each test specimen so that it can be identified throughout the test. 7.5 Number of test specimens a) Six treated test specimens (no more than two originating from the same tree unless taken at random from a stock of more than 500) for each preservative, each concentration and each duration of treatment; b) Three untreated control test specimens (each originating from a different tree unless taken at random from a stock of more than 500) for a complete test of any given preservative; c) Three control test specimens treated with the solvent or diluent (5.2.3 or 5.2.4) (each originating from a different tree unless taken at random from a stock of more than 500) if a solvent or diluent (including water) is used. Control test specimens under c) may be omitted if the solvent or diluents is water of drinking quality. When dipping is to be used (8.1.3.3) it is advisable to treat more than the specified number of test specimens so that, after weighing, any test specimens with abnormally high or low retentions can be rejected from the batch. NOTE To gain further information on a formulation the manufacturer may find it useful to test a version of the preservative where the active ingredient(s) has been removed.
2) For special tests, test specimens may be obtained according to a given series. As a result, it may be preferable to take test specimens from pretreated strips. Where pretreated strips are used details should be included in the test report. SIST EN 46-1:2016
EN 46-1:2016 (E) 10 8 Procedure 8.1 Preparation of the test specimens 8.1.1 Conditioning of the test specimens prior to sealing Allow the test specimens to condition in the conditioning chamber (5.3.2) for a minimum of two weeks. 8.1.2 Sealing of the transverse faces 8.1.2.1 General When treatment is to be by brushing or by pipette then only the transverse faces of test specimens shall be sealed. When treatment is to be by dipping then all faces, except one 25 mm x 50 mm face, shall be sealed. The material used for sealing shall be resistant to the penetration of wood preservatives under test. The sealings specified in 8.1.2.2 and 8.1.2.3 have been proven as suitable. 8.1.2.2 For tests with solutions in which water is the continuous phase, apply three coats of the paraffin wax (5.2.1) at about 90°C so that the first coat adheres closely to the wood and the successive coatings bond to one another. Condition the sealed test specimens in the conditioning chamber (5.3.2) for at least one day. 8.1.2.3 For tests with preservative solutions in which the continuous phase is an organic solvent that dissolves paraffin wax, use the gelatine (5.2.2): apply the first coat as an aqueous solution of 200 g/l at 40°C, then after a minimum of 8 h of drying, apply two further coats of an aqueous solution of 300 g/l at 50°C. Condition the sealed test specimens in the conditioning chamber (5.3.2) for at least one day. 8.1.3 Treatment of the test specimens 8.1.3.1 Preparation of the treatment solutions 8.1.3.1.1 Solid preservatives — Water-soluble preservatives: Dissolve the preservative in the water (5.2.3) to the required concentration, or in a series of concentrations if toxic values are to be determined. — Non-water-soluble preservatives: Dissolve the preservative in an appropriate solvent (5.2.4) to the required concentration, or in a series of concentrations if toxic values are to be determined. All treatment solutions shall be freshly prepared. 8.1.3.1.2 Liquid preservatives If appropriate, use the preservative without further preparation other than any necessary stirring. If it is a concentrate or if toxic values are to be determined, dilute the preservative with the diluent to the required working concentration, using the procedure specified by the manufacturer. All treatment solutions shall be freshly prepared. SIST EN 46-1:2016
EN 46-1:2016 (E) 11 8.1.3.1.3 Toxic values If toxic values are to be determined, prepare a series of at least five concentrations by mass, distributed evenly about the expected toxic values. A solvent or diluent control, i.e. treatment at concentration = 0, shall also be used. If the approximate toxic values are unknown, the concentrations shall form a widely spaced geometric progression for a first test and a more closely spaced geometric or arithmetic progression for subsequent tests. All treatment solutions shall be freshly prepared. 8.1.3.2 Treatment by brushing or by pipette In the laboratory work area (5.3.3) apply the preservative either by brushing or by pipette to the 50 mm x 25 mm lateral face that would have been furthest from the centre of the tree. Depending on the type of treatment, the volume (application by pipette) or mass (application by brushing) of the treatment solution shall be determined to obtain the surface application specified by the manufacturer. Place the specimens such that the 50 mm x 25 mm lateral face that is to be treated is uppermost and apply the appropriate fluid uniformly to that face. When the preservative is applied by brush, place the test specimens on a balance while being brushed to determine the amount of preservative applied to the nearest 0,01 g. When the preservative is applied by pipette, move the pipette across the fibre direction and the amount of preservative applied shall be determined to the nearest 0,01 ml. Several applications can be necessary to apply the required amount. In this case the coats should be applied sufficiently quickly to avoid any solidification of certain substances which can impede the penetration of further coats. Care should be taken to avoid fluid running off the lateral face being treated. 8.1.3.3 Treatment by dipping When the treatment of specimens is by dipping all faces, except one 25 mm x 50 mm face, shall be sealed (see 8.1.2). Weigh to the nearest 0,01 g each sealed test specimen, to obtain its initial mass. Treat each test specimen in the treatment vessel (5.3.5) as follows: Immerse completely in the solution. The dipping times to be used shall be one of the following, agreed beforehand according to the purpose of the test: — Either one 10 s period and/or two periods of 10 s at an interval of 24 h. If the rate of solidification of some constituents of a preservative formulation would have the effect of retarding its penetration during the second dipping, this interval has to be reduced. The interval employed shall be mentioned in the test report. — Or a period sufficient for a determined quantity to be retained by the test specimen3). Using forceps, remove each test specimen from the preservative fluid and sponge off fluid from all the sealed faces of the specimen. Keeping the face that has not been sealed upper most, immediately weigh to the nearest 0,01 g.
3) The dipping time depends upon the type of preservative and may extend to several hours for water-soluble preservatives. The progress of absorption is monitored by successive weighings of the treated test specimens. For this long period dipping the treated test specimens a
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