1、BRITISH STANDARD BS7451:1991 Specification for Archival quality bookbinding leatherBS7451:1991 This BritishStandard, having been prepared under the directionof the Textiles and Clothing Standards Policy Committee, was published underthe authority of the Standards Board and comes into effect on 30Aug
2、ust1991 BSI12-1999 The following BSI references relate to the work on this standard: Committee reference TCM/17 Draft for comment90/47080 DC ISBN 0 580 19763 8 Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted by the Textiles and Clothing Standards
3、 Policy Committee (TCM/-) to Technical Committee TCM/17, upon which the following bodies were represented: British Clothing Industry Association British Footwear Manufacturers Federation British Leather Confederation Chief and Assistant Chief Fire Officers Association Consumer Policy Committee of BS
4、I Footwear Distributors Federation Hides and Allied Trades Improvement Society Institute of Trading Standards Administration Ministry of Defence Overseas Development Natural Resources Institute SATRA Footwear Technology Centre Scottish Hide, Skin and Tallow Markets Limited Society of Leather Technol
5、ogists and Chemists The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Bodleian Library British Library Edward James Foundation Leather Conservation Centre National Library of Scotland National Library of Wales Public Record Office Trinity C
6、ollege Dublin Amendments issued since publication Amd. No. Date CommentsBS7451:1991 BSI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Sampling 1 4 Conditioning 1 5 Chemical and physical properties 1 6 Marking 2 Appendix A Background informa
7、tion to the standard 3 Appendix B Method of test for tarnishing 3 Appendix C Calculation of surface shrinkage in boiling water 5 Figure 1 Assembly as used for test samples 4 Figure 2 Assembly as used for control samples 5 Table 1 Chemical properties 1 Table 2 Physical properties 1 Publication(s) ref
8、erred to Inside back coverBS7451:1991 ii BSI 12-1999 Foreword This BritishStandard has been prepared under the direction of the Textiles and Clothing Standards Policy Committee. It specifies the chemical and physical properties of bookbinding leather where the overall priority is long term stability
9、 when exposed to atmospheric pollutants. It is based on data obtained from long term natural ageing of leathers and accelerated ageing in a deterioration chamber. It provides purchasers of new binding leather with an assurance of archival quality leather. Further information on the background to thi
10、s standard is given in Appendix A. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summar
11、y of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front co
12、ver.BS7451:1991 BSI 12-1999 1 1 Scope This BritishStandard specifies requirements for leather to be used in archival bookbinding, for which purpose the following leathers are suitable: a) semi-alum leather, as defined in BS2780 (term234); b) chrome re-tan leather, in which the leather has been first
13、 chrome tanned throughout its thickness, then tanned with vegetable tanning agents, as defined in BS2780 (term52) and is then further treated with basic aluminium salts. Leathers tanned solely with vegetable tannins, or chrome re-tan leather in which the chrome tanned leather has been further tanned
14、 solely with vegetable tanning agents, are not suitable and are thereby excluded. In addition, although alum tawed bindings have been proved to have long term durability, alum tawing cannot be regarded as a true tannage and therefore such leather is not included in this specification. NOTEThe titles
15、 of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this BritishStandard, the definitions given in BS2780 apply. 3 Sampling Samples for physical testing shall be taken in accordance with method1 of BS3144:1968. Samples for chemical
16、 testing shall be taken in accordance with method1 of BS1309:1974. 4 Conditioning Samples shall be conditioned in accordance with method2 of BS3144:1968. 5 Chemical and physical properties The finished leather shall comply with the requirements given in Table 1 and Table 2 when tested in accordance
17、with the methods described therein. Table 1 Chemical properties Table 2 Physical properties Chemical property Method of test Requirement Semi-alum leather Chrome re-tan leather further treated with aluminium salts Aluminium content expressed as Al 2 O 3 acontent Method15 of BS1309:1974 Not less than
18、2.8% Not less than1.9% Chromium content expressed as Cr 2 O 3 acontent Method8 of BS1309:1974 None Not less than2.0% pH Method9 of BS1309:1974 Not less than4.0 Not less than4.0 Tarnish Appendix B No difference in tarnishing between test foil and control foil No difference in tarnishing between test
19、foil and control foil a Values are expressed on mass of leather containing14% moisture. Physical property Method of test Requirement Semi-alum leather Chrome re-tan leather further treated with aluminium salts Shrinkage temperature Method17 of BS3144:1968 Not less than115 C Not less than110 C Tear s
20、trength Method6 of BS3144:1968 Not less than25N Not less than25N Flexural endurance BS5131-4.2 Not less than100000 Not less than100000 Surface shrinkage in boiling water Appendix C Not greater than2% Not greater than2%BS7451:1991 2 BSI 12-1999 6 Marking 6.1 The leather shall be marked with the manuf
21、acturers name, trademark or other means of identification. 6.2 The leather shall be supplied with a label or invoice marked with the following information: a) the number and date of this BritishStandard, i.e.BS7451:1991 1) ; b) the type of leather tanning used in processing, i.e.semi-alum leather or
22、 chrome re-tan leather further treated with basic aluminium salts; c) the tannery batch number. 1) Marking BS7451:1991 on or in relation to a product represents a manufacturers declaration of conformity, i.e.a claim by or on behalf of the manufacturer that the product meets the requirements of the s
23、tandard. The accuracy of the claim is therefore solely the responsibility of the person making the claim. Such a declaration is not to be confused with third party certification of conformity, which may also be desirable.BS7451:1991 BSI 12-1999 3 Appendix A Background information to the standard The
24、 need for a standard for archival leather was considered necessary because of the lack of any reliable guide by which purchasers of new binding leather could be assured of obtaining a leather with long term stability to acidic atmospheric pollutants. Previously reliance had been placed on one of the
25、 following. a) Purchasing leather from specific regions of the world where the reputation for long term durability had been gained from the use of vegetable tannins extracted from indigenous vegetation. Now the worldwide distribution of commercial vegetable tanning extracts has led to the use of tan
26、nins that may differ substantially from those of indigenous vegetation. As a consequence, reliance can no longer be placed on geographical origin. b) A test which had been devised by PIRA International. However, long term natural ageing in an urban atmosphere has proved this test to be an unreliable
27、 guide. Long term natural ageing in an urban atmosphere has shown that vegetable tanned leather tends to deteriorate far more rapidly than chrome tanned leather, but chrome tanned leather lacks those properties, such as malleability and ease of tooling, which are required of a binding leather. Accel
28、erated ageing in a deterioration chamber has shown that the resistance of vegetable tanned leather to acidic atmospheric pollutants can be substantially increased by further treatment with basic aluminium salts. Chrome tanned leather re-tanned with vegetable tanning agents can produce a chrome re-ta
29、n leather with the properties of a binding leather but the presence of the vegetable tannins reduces the durability of the leather, particularly of the grain surface. It has been found that if such a leather is given an additional treatment with basic aluminium salts it will show improved stability
30、to acid pollutants. Comparative trials, in which commercial binding leathers prepared by various tanning processes have been exposed to acidic pollutants in a deterioration chamber, have demonstrated the superior durability of these alum combination tanned leathers which now form the basis of this s
31、pecification. Appendix B Method of test for tarnishing B.1 Principle Two test specimens of leather are placed in separate atmospheres of40 2 C, the relative humidity of these atmospheres being maintained by the water vapour pressure of a saturated solution of sodium chloride, also at40 2 C. The firs
32、t test specimen is kept in contact with silver foil and the second test specimen is kept in contact with copper foil for a period of6weeks. The silver foil and the copper foil are then compared with similar pieces of silver foil and copper foil which have been subjected to the same conditions but in
33、 the absence of any leather. The surfaces are examined to see if the presence of the leather has visibly increased the degree of tarnishing. NOTEThe saturated sodium chloride solution maintains75%r.h. in the test atmosphere. B.2 Apparatus and reagents B.2.1 Cutting device, capable of cutting the lea
34、ther sample and the metal foils (B.2.2 andB.2.3). B.2.2 Silver foil B.2.3 Copper foil B.2.4 Acetone B.2.5 Pipette or similar device, capable of dispensing1.0 0.1mL of sodium chloride solution. B.2.6 Saturated sodium chloride solution B.2.7 Four small glass sample tubes, with an internal diameter not
35、 greater than10mm and of approximately60mm in length. B.2.8 Four large glass sample tubes, with a means of sealing their tops, with an internal diameter not less than14mm and of approximately100mm in length. B.2.9 Incubator or conditioning cabinet, capable of maintaining a temperature of40 2 C. B.3
36、Procedure B.3.1 Using the cutting device(B.2.1), cut two rectangles with sides10 1mm in length from each of the sheets of silver foil(B.2.2) and copper foil(B.2.3). Degrease the rectangles by washing with acetone(B.2.4) and allowing the acetone to evaporate. Similarly, cut two rectangles with sides1
37、0 1mm in length from a sample of the leather to be tested.BS7451:1991 4 BSI 12-1999 B.3.2 Using a pipette or similar device(B.2.5), dispense1.0 0.1mL of saturated sodium chloride solution(B.2.6) into the bottom of the first of the four small glass sample tubes(B.2.7), ensuring that the saturated sod
38、ium chloride solution does not wash the wall of the small glass tube near the top. Place this small glass sample tube inside the first of the four large glass sample tubes(B.2.8), taking care to ensure that the salt solution remains inside the small glass sample tube and does not wash the inner wall
39、 of the small tube near the top. NOTEThe reason for preventing the saturated sodium chloride solution from washing the top of the wall of the small tube is to ensure that, at a later stage, the rectangles of metal foil and leather do not make contact with the sodium chloride solution. B.3.3 Place th
40、e first of the two rectangles of leather into the large glass tube so that it rests on the open top of the small glass tube. B.3.4 Place the first of the two rectangles of silver foil on top of the rectangle of leather and seal the tube as illustrated in Figure 1. B.3.5 RepeatB.3.2 andB.3.3 using th
41、e second of the small glass sample tubes, the second of the large glass sample tubes and the second of the two rectangles of leather. Place the first of the two rectangles of copper foil on top of the rectangle of leather and seal the tube as illustrated in Figure 1. B.3.6 RepeatB.3.2 using the thir
42、d of the small glass sample tubes and the third of the large glass sample tubes. Place the second of the two rectangles of silver foil into the large glass tube so that it rests on the open top of the small glass tube and seal the tube as illustrated in Figure 2. B.3.7 RepeatB.3.2 using the fourth o
43、f the small glass sample tubes and the fourth of the large glass sample tubes. Place the second of the two rectangles of copper foil into the large glass tube so that it rests on the open top of the small glass tube and seal the tube as illustrated in Figure 2. B.3.8 Place the four large tubes toget
44、her with their contents, in an incubator or conditioning cabinet(B.2.9) at40 2 C. After6weeks remove them from the incubator or conditioning cabinet, remove the seals, and remove the four metal foil rectangles from the large tubes. B.3.9 Compare the upper and lower surfaces of the samples of the rec
45、tangles of metal foil taken from the first and second tubes with the upper and lower surfaces of those taken from the third and fourth tubes. Examine them to see if there is a visible difference in the extent to which the metal foils used as test samples (i.e.in the first and second tubes) are tarni
46、shed more than the metal foils used as control samples (i.e.in the third and fourth tubes). B.4 Test report Report which, if any, of the surfaces of the rectangles of metal foil used in the test (i.e.in the first and second tubes) are tarnished more than the metal foils used as control samples (i.e.
47、in the third and fourth tubes). Figure 1 Assembly as used for test samplesBS7451:1991 BSI 12-1999 5 Appendix C Calculation of surface shrinkage in boiling water Carry out the procedure given in method16 of BS3144:1968, but boil for only2min as compared with the15min given in16.4.5 of BS3144:1968. Ca
48、lculate the percentage surface shrinkage from the equation Figure 2 Assembly as used for control samples where S is the surface shrinkage (in%); d 0 is the mean of the four marked diameters at the start of the test (inmm); d 1 is the mean of the four marked diameters at the end of the test (inmm). S
49、 100 d 0 2 d 1 2 d 0 2 - =6 blankBS7451:1991 BSI 12-1999 Publication(s) referred to BS1309, Methods of sampling and chemical testing of leather. BS2780, Glossary of leather terms. BS3144, Methods of sampling and physical testing of leather. BS5131, Methods of test for footwear and footwear materials. BS5131-4.2, Flexing index of fibreboard. BS7451:1991 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandard
