1、BRITISH STANDARD BS 3987:1991 Incorporating Amendment No. 1 Specification for Anodic oxidation coatings on wrought aluminium for external architectural applications ICS 25.220.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS 3987:1991 This British Standard, having been pre
2、pared under the direction of the Surface Coatings (other than Paints) Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 20 December 1991 BSI 06-2001 First published March 1966 Second edition July 1974 Third edition December 1991 The followi
3、ng BSI references relate to the work on this standard: Committee reference SRC/32 Draft for comment 91/50611 DC ISBN 0 580 20089 2 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Surface Coatings (other than Paints) Standards Policy Comm
4、ittee (SRC/-) to Technical Committee SRC/32, upon which the following bodies were represented: Aluminium Federation Aluminium Finishing Association Aluminium Window Association Association of Builders Hardware Manufacturers British Lock Manufacturers Association British Metal Finishing Suppliers Ass
5、ociation Institute of Corrosion Institute of Metal Finishing Institution of Chemical Engineers Metal Finishing Association Metal Window Federation Ltd. Amendments issued since publication Amd. No. Date Comments 10944 June 2001 Indicated by a sidelineBS 3987:1991 BSI 06-2001 i Contents Page Committee
6、s responsible Inside front cover Foreword ii Specification 1S c o p e 1 2 Definitions 1 3 Visual inspection after anodizing 2 4 Colour 2 5T h i c k n e s s 3 6S e a l i n g 3 7 Cold impregnation 4 8 Surface abrasion resistance 4 Appendix A Guidance on information to be supplied 5 Appendix B Guidance
7、 on properties affecting coating performance 5 Appendix C Choice of aluminium for anodizing 6 Appendix D Handling and temporary protection during transportation and installation 6 Appendix E Maintenance of anodized aluminium 6 Appendix F Surface texture 7 Appendix G Visual inspection after anodizing
8、 7 Appendix H Colour 7 Appendix J Examples of average and local thickness requirements 8 Appendix K Sealing quality: production control methods 8 Appendix L Guidance on sampling 8 Figure 1 Measuring points 3 Publication(s) referred to Inside back coverBS 3987:1991 ii BSI 06-2001 Foreword This revisi
9、on of BS 3987 was prepared under the direction of the Surface Coatings (other than Paints) Standards Policy Committee. It gives a specification for anodic oxidation coatings on wrought aluminium for external architectural applications. It supersedes the previous edition, BS 3987:1974, which is withd
10、rawn. The architect or designer of architectural components is advised to consult with the aluminium supplier to ensure that the correct grade of aluminium is selected in order to produce the required finish and with the anodizer to ensure that the dimensions and configuration of the components are
11、such that the requirements of this standard can be met as an economic proposition. It is important to note that anodizing requirements should be considered at the design stage and attention of designers is drawn to BS 4479-5. The anodized surface develops a characteristic appearance depending on the
12、 grade of aluminium and the anodizing process used. Such coatings, which do not incorporate colouring matter, are known as “clear” (or sometimes “natural” or “silver”) anodized aluminium. This revision of BS 3987 differs from the previous edition in that guidance is given in appendices on informatio
13、n to be supplied by the purchaser to the anodizer, on the selection of aluminium, on the surface texture and on sampling. The significant surface is defined and is no longer specified by the purchaser and colour fastness is specified. Values for thickness and the surface abrasion resistance of the c
14、oatings are also given. 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. Summary of pages
15、This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 9, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued.BS 3987:1991 BSI 06-2001 1 1 Scope This British Standard specifies requir
16、ements for clear and coloured anodic oxidation coatings on wrought aluminium for external architectural applications. Guidance on the information to be supplied by the purchaser to the anodizer is given in Appendix A. Guidance on properties affecting coating performance is given although reflectance
17、 and gloss are not specified (see Appendix B). NOTE 1 The coatings consist mainly of aluminium oxide and are produced by an electrolytic oxidation process during which the aluminium acts as the anode. NOTE 2 The composition of the aluminium is not specified but that used is assumed to be suitable fo
18、r anodizing (see Appendix C). NOTE 3 Temporary protection and maintenance of anodized aluminium after anodizing may be necessary (see Appendix D and Appendix E). NOTE 4 The titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of
19、this British Standard the following definitions apply. 2.1 aluminium aluminium and aluminium-based alloys 2.2 anodized aluminium aluminium with an anodic oxidation coating, produced by an electrolytic oxidation process in which the surface of aluminium is converted to a coating, generally an oxide,
20、having protective, decorative or functional properties 2.3 clear anodized aluminium anodized aluminium with a substantially colourless, translucent anodic oxidation coating NOTE This is colloquially known as natural anodized aluminium. 2.4 colour anodized aluminium anodized aluminium coloured either
21、 during anodizing or by subsequent processing 2.5 integral colour anodized aluminium anodized aluminium that has been anodized using an appropriate (usually organic acid-based) electrolyte which produces a coloured coating during the anodizing process itself 2.6 electrolytically coloured anodized al
22、uminium anodized aluminium with an anodic oxidation coating that has been coloured by the electrolytic deposition of a metal or metal oxide in the pore structure 2.7 dyed anodized aluminium anodized aluminium with an anodic oxidation coating coloured by absorption of dyestuffs or pigments into the p
23、ore structure 2.8 combination colour anodized aluminium anodized aluminium with an anodic oxidation coating that has been coloured by electrolytic colouring, or produced by integral colour anodizing, followed by absorption dyeingBS 3987:1991 2 BSI 06-2001 2.9 interference colour anodized aluminium a
24、nodized aluminium with an anodic oxidation coating coloured by means of optical interference effects 2.10 significant surface the part of the article covered or to be covered by the coating, for which the coating is essential for serviceability and/or appearance, and which is the surface intended to
25、 be exposed in service 2.11 average thickness the mean value of at least five local coating thickness measurements that are evenly distributed over the significant surface of a single anodized piece 2.12 local coating thickness the mean of the coating thickness measurements of which not fewer than t
26、hree are made within a small area (10 mm diameter, or less) of the significant surface of a single anodized piece 2.13 sealing treatment of anodic oxidation coatings on aluminium to reduce porosity and the absorption capacity of the coating by hydrothermal processes carried out after anodizing 2.14
27、cold impregnation treatment of anodic oxidation coatings on aluminium to plug the pores and reduce the absorption capacity of the coating by chemical processes carried out at low temperatures after anodizing 3 Visual inspection after anodizing Anodized articles shall be free from visible defects on
28、the significant surface(s) when viewed from a distance of not less than 5 m for external architectural applications or 3 m for internal architectural applications (see Appendix F and Appendix G). 4 Colour The colour anodizing method, if used, shall be such that a light fastness rating of 9 or greate
29、r is achieved when samples anodized to this specification are tested by means of BS 6161-7 or BS EN 12373-8 (see Appendix H).BS 3987:1991 BSI 06-2001 3 5 Thickness 5.1 Thickness of coating The average thickness of the anodic oxidation coating on a single component shall be not less than 25 m. At no
30、point on the significant surface(s) shall the local coating thickness be less than 20 m (see 5.2 and Appendix J). 5.2 Measurement of thickness The thickness of the anodic oxidation coating shall be measured by one of the methods given in BS EN ISO 1463 or BS EN ISO 2360. In cases of dispute the meth
31、od given in BS EN ISO 1463 shall be used as the referee method. The minimum average thickness shall be determined on each component being tested by measuring the local thickness at not less than five measuring points over the significant surface of the component (see Figure 1). At each measuring poi
32、nt three readings shall be taken and averaged to determine the local thickness value. 6 Sealing 6.1 General Clear anodized and colour anodized aluminium shall be sealed. 6.2 Sealing quality The method described in BS EN 12373-7 shall be used as the referee method. When tested by this method the mass
33、 loss from the sealed anodic oxidation coating shall be not greater than 3.0 g/m 2of anodized surface tested. NOTE 1 For production control purposes the sealing quality may be determined using the mass loss, dye spot or measurement of admittance methods described in BS EN 12373-4, -5 or -7 (see Appe
34、ndix K). NOTE 2 It is often useful to evaluate sealing quality by means of more than one test method. NOTE Examples of average and local thickness requirements are given in Appendix J. Figure 1 Measuring pointsBS 3987:1991 4 BSI 06-2001 7 Cold impregnation If hydrothermal sealing is not required, ap
35、propriate cold impregnation processes based on nickel fluoride shall be specified. The quality of cold impregnation is also very important, and the test methods to be used are those specified in 6.2. NOTE In external architectural applications, the cold impregnation process should be followed by an
36、additional sealing step, such as a short period of conventional sealing, or by nickel sulfate treatment at above 60 C. 8 Surface abrasion resistance When tested by the method described in BS 6161-18, using glass coated paper, coatings produced by sulfuric acid anodizing shall not be abraded. When te
37、sted by the method described in BS 6161-18, using garnet coated paper, coatings produced by integral colour anodizing shall not be abraded.BS 3987:1991 BSI 06-2001 5 Appendix A Guidance on information to be supplied A.1 General The requirements of this specification relate to thickness, sealing qual
38、ity, colour fastness and surface abrasion resistance. However the purchaser, when ordering, may need to specify further requirements or the anodizer may need additional information in order to meet the requirements of this specification. This appendix gives guidance on the information to be supplied
39、 in such cases. A.2 and A.3 give details of this information. A.2 Information which should be supplied The purchaser should supply the following information essential to the anodizer. a) The specification of the aluminium (see Appendix C). NOTE 1 This is essential to ensure that the agreed finish an
40、d/or properties can be achieved. b) The extent of the significant surface(s), indicated, for example, by drawings or by the provision of suitably marked samples. NOTE 2 In some cases there may be different requirements for the finish on different parts of the significant surface(s). NOTE 3 Essential
41、 jigging on significant surfaces will result in marking and locally reduced thickness of the coating at the contact points. c) The surface texture(s) required (see Appendix F). NOTE 4 It may be appropriate for acceptable limits of variation of final surface finish on the significant surface(s) to be
42、 agreed between the purchaser and the anodizer, preferably by the provision of agreed samples. d) The sampling procedure to be adopted (see Appendix L). A.3 Additional information which should be supplied in the case of coloured coatings The purchaser should supply the following additional informati
43、on to the anodizer in the case of coloured coatings: a) the colour required (see clause 4 and Appendix H); b) the colouring method; c) the colour tolerances required, defined by agreed samples (see clause 4 and Appendix H). Appendix B Guidance on properties affecting coating performance The performa
44、nce of an architectural anodic oxidation coating can be assessed by three main properties, namely the following: a) anodic oxidation coating thickness; b) seal quality; c) surface abrasion resistance to weathering. The anodic oxidation coating thickness will strongly influence the corrosion resistan
45、ce of the finish, and the seal quality is a measure of the resistance of the coating to staining and corrosion. The weathering performance of the coating is affected by its surface abrasion resistance; a soft coating produces a white bloom, described as chalking, upon exposure to the elements. This
46、can result in an unacceptable appearance and rapid erosion of the anodic oxidation coating which in turn affects the corrosion resistance. Production line non-destructive tests for anodic oxidation coating thickness and seal quality are well established and the test equipment to carry out these test
47、s is readily available. Surface abrasion resistance is a valid method of assessing the weathering resistance of an anodic oxidation coating; the higher the anodizing electrolyte concentration and temperature and the longer the immersion time in the electrolyte the lower will be the abrasion resistan
48、ce of the coating. In general the lower the abrasion resistance the more likely the coating is to chalk. There are two types of laboratory test used to measure abrasion resistance, namely, the abrasive wheel test and the jet test; these tests are described in BS EN 12373-9 and -10 respectively. The
49、abrasive wheel test measures the abrasion resistance of the surface of the anodic finish which is the part of the coating exposed to the elements. The jet test measures the average abrasion resistance of the coating and as such is not as informative in this context as the abrasive wheel test.BS 3987:1991 6 BSI 06-2001 Tests carried out suggest that for sulfuric acid anodic oxidation coatings a wear index of 1.2 when measured by the abrasive wheel test should be consistently obtainable and that any coating with a wear index greater than 1.4 is likely to be of unsa
