1、BRITISH STANDARD BS 3900-A5: 1991 Methods of test for Paints Part A5: Large-scale brushing tests for paints and varnishes It is recommended that this Part be read in conjunction with the general introduction of BS3900-0BS3900-A5:1991 This British Standard, having been prepared under the directionof
2、the Pigments, Paints and Varnishes Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 31 May 1991 BSI 07-1999 First published 1968 Second edition May 1991 The following BSI references relate to the work on this standard: Committee reference
3、PVC/10 Draft for comment 88/50749 DC ISBN 0 580 17607 X Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Pigments, Paints and Varnishes Standards Policy Committee (PVC/-) to Technical Committee PVC/10, upon which the following bodies were
4、 represented: British Gas plc Chemical Industries Association Health and Safety Executive Institute of Metal Finishing Ministry of Defence Oil and Colour Chemists Association Paint Research Association Paintmakers Association of Great Britain Ltd. Titanium Pigment Manufacturers Technical Committee A
5、mendments issued since publication Amd. No. Date CommentsBS3900-A5:1991 BSI 07-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Principle 1 3 Materials 1 4 Preparation of panels for test 1 5 Procedure for painting and varnishing 4 6 Test report 6 Figure 1 Two se
6、ctions of moulding complying with design S20 of BS1186-3 1 Figure 2 Directions of laying off and arrangement of panel prepared inaccordance with 5.2.1 2 Figure 3 Directions of laying off and arrangement of panel in accordance with 5.2.2 3 Publications referred to Inside back coverBS3900-A5:1991 ii B
7、SI 07-1999 Foreword This Part of BS3900 has been prepared under the direction of the Pigments, Paints and Varnishes Standards Policy Committee. It is a revision of BS3900-A5:1968, which is superseded and withdrawn. The method of test described gives a procedure for applying a paint (top coat, underc
8、oat or primer) or varnish to a substrate and assessing the brushing and flow characteristics. For comparison purposes, a parallel determination is made on a reference paint or varnish with established properties and which is also applied to a substrate representing the end use for which coating mate
9、rial is intended. A selection of substrates is specified. Before the method can be applied, the product specification or other document making reference to it should detail the substrate and the reference coating material to be used. NOTE 1The reference coating material will frequently be chosen by
10、the exchange of an agreed material between the parties concerned and alternative substrates may also be chosen by agreement. NOTE 2In this method of test there is a degree of subjectivity relating to the way in which the paint is applied to the test panels by the painter. NOTE 3For some coating mate
11、rials or end uses some additional defects may be critical. Inspection for these should be additionally detailed when this method is to be applied. There is no international standard corresponding to this method but Technical Committee35, Paints and Varnishes, of the International Organization forSta
12、ndardization has prepared a method that has been published as ISOTR3172:1974. It has been assumed in the drafting of this standard that it will be used and applied by those who are appropriately qualified and experienced. A British Standard does not purport to include all the necessary provisions of
13、 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 This document comprises a front cover, an inside front cover, pagesi andii, pages1to6, an inside back
14、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 cover.BS3900-A5:1991 BSI 07-1999 1 1 Scope This Part of BS 3900 describes a method for assessing the brushing and fl
15、ow characteristics of paints and varnishes when applied to large areas of closely defined substrates. It can also be used to observe other properties, such as the tendency of the paint or varnish to retract from sharp edges and protuberances, e.g. mouldings, rivet heads, weld seams, etc. with conseq
16、uent loss of opacity and protective power. NOTE 1As an adequate wet edge time is important for brush application to large areas, it is recommended that the wet edge time test in accordance with BS3900-C1 be carried out in conjunction with this test. NOTE 2The titles of the publications referred to i
17、n this standard are listed on the inside back cover. 2 Principle Paint or varnish is applied by brush in a specified manner to a specified substrate with or without mouldings or other protrusions. The brushing and flow characteristics of the paint (top coat, undercoat or primer) or varnish are compa
18、red with those of a similar material selected for reference purposes. 3 Materials 3.1 Reference coating material A paint or varnish of similar type to the test coating material shall be used for performance comparison purposes (see the foreword). 3.2 Test panels The substrate material shall be chose
19、n to suit the type of paint or varnish under test and its proposed usage. Solvent-borne finishing paints and undercoats shall be tested on filled plywood or primed metal panels; wood primers on unfilled plywood panels; wood varnishes over presealed plywood panels; and waterborne paints on plasterboa
20、rd or hardboard or for some purposes on unfilled plywood panels. The system used shall be that normally employed in practice, e.g. a finishing paint shall be applied on a primed (or filled) and undercoated panel and an undercoat on a primed or filled panel. NOTEIf, in practice, the paint is to be us
21、ed on a special substrate or special preparation of the substrate, then the panel used for the test should be chosen and prepared in accordance with these requirements which should be separately detailed. 4 Preparation of panels for test 4.1 General Compare paints or varnishes on similarly treated s
22、urfaces only. 4.2 Wood panels 4.2.1 Material Use birch-faced plywood, complying with type MR of BS6566-8, measuring not less than1.2m 0.9m 9mm. If a moulding is desired, use two strips of moulding. Make up each from two lengths of moulding complying with design S20 of BS1186-3, nailed or glued back-
23、to-back as shown inFigure 1. The two strips shall be approximately 1m long and 0.75m long. Both shall be mitred at 45 at one end and fitted together to make a right-angled corner. Nail or glue the strips of moulding to the panel so that they are 150mm from, and parallel to, the edges of the panel (s
24、eeFigure 2 andFigure 3). NOTEAlternative wood surfaces to plywood panels may be used by agreement between the interested parties, e.g. half panel door with mouldings. 4.2.2 Preparation for painting and varnishing Rub down the face of the panel and the moulding, if any, with grade No.0 glass paper co
25、mplying with BS871. Rub until a smooth surface is obtained, taking care not to round the sharp edges of the moulding. If an undercoat or finish only is being tested, the panel may be filled by applying a suitable high-build surfacer to the front of the panel and the moulding. If a wood varnish is be
26、ing tested, completely seal the panel with at least two sealer coats of a varnish similar to that under test. Allow at least 24h drying, then rub the panel down with grade No.0 glass paper complying with BS871, until a smooth surface is obtained. Figure 1 Two sections of moulding complying with desi
27、gn S20 of BS1186-3BS3900-A5:1991 2 BSI 07-1999 Figure 2 Directions of laying off and arrangement of panel prepared in accordance with5.2.1BS3900-A5:1991 BSI 07-1999 3 Figure 3 Directions of laying off and arrangement of panel in accordance with5.2.2BS3900-A5:1991 4 BSI 07-1999 4.2.3 Reuse of panels
28、For testing paint systems other than primers and varnishes, panels from previous tests may be reused provided the surface has been wet abraded until the gloss of the previous test paint has been entirely removed and a smooth surface free from brush marks has been obtained. Use for this purpose silic
29、on carbide paper, Cweight, not coarser than grade P220, complying with BS871. Renew any mouldings if the sharp edges have become rounded. NOTEWhen coated plywood panels are to be wet abraded, it is a useful precaution to coat the back and edges of the panel with one or more coats of a paint to preve
30、nt water entering the panel and causing the ply to lift. 4.3 Steel panels 4.3.1 Material Use steel sheet of thickness approximately 1.25mm complying with CR3/FF of BS1449-1, flattened and oiled and measuring not less than 1.2m 0.9m. NOTEPlain steel panels only are specified, but in practice, the per
31、formance of paints when applied over rivet heads, angle brackets, welds, etc. is important. Special steel panels with rivets, brackets or welds fixed so as to reproduce practical conditions, or portions of metal fabricated structures, may therefore be used, if required, by agreement between the inte
32、rested parties. 4.3.2 Preparation for painting Prepare the panel in accordance with3.3 of BS3900-A3:1986. NOTEWhere, in practice, other methods of preparation are used, for example grit blasting, phosphating or zinc or aluminium spraying, and where it is considered that such preparation may affect t
33、he application properties of the paint, the method to be used should be detailed. 4.3.3 Reuse of steel panels Recover plain steel panels in accordance with4.2.3. Alternatively, to remove the entire paint coating use a paint remover and prepare the panel in accordance with4.3.2. 4.4 Plasterboard pane
34、ls 4.4.1 Material Use gypsum plasterboard complying with type1 of BS1230-1 of not less than 1.2m 0.9m 9mm dimensions. For painting, use the face designed to receive decoration directly, i.e. the paper-lined face. 4.4.2 Preparation for painting Remove any loose particles from the surface using a dry
35、paint brush and seal cut edges of the panels with an adhesive tape. 4.5 Hardboard panels 4.5.1 Material Use the smooth surface of hardboard complying with BS1142-2 and measuring not less than1.2m 0.9m 5mm. 4.5.2 Preparation for painting Remove any loose particles from the surface using a dry paint b
36、rush. 5 Procedure for painting and varnishing 5.1 General At the same time as coating panels with the material under test, coat duplicate panels in the same manner with the reference coating material (see3.1) so that performances may be compared. 5.2 Solvent-borne paints and varnishes 5.2.1 Testing
37、single paints 5.2.1.1 Primers Primers shall be tested on panels, according to the function of the primers, prepared in accordance with4.2.2, 4.3.2, 4.4.2 or4.5.2, as appropriate. One panel shall be prepared for each primer under test and one panel similarly prepared for the reference primer. Place o
38、ne of the panels firmly in a vertical position, e.g. on a rigid stand or frame, with the longer dimension upright. Remove any dust from the surface with a soft lint-free cloth or tack rag. Apply the reference primer to the test surface using a25mm or 50mm brush for the moulding, if any, and a 50mm o
39、r 75mm brush for the rest of the panel. Use a 75mm brush on panels without moulding. Lay off the paint in the direction shown inFigure 2. Repeat the procedure with each primer under test using clean brushes identical in type and size with those used for the reference primer. Note any differences in
40、application properties. Allow the primers to dry for 24h, with the panels in a vertical position. NOTEOther drying periods may be agreed between the interested parties if thought appropriate. Compare the primers under test with the reference primer for freedom from brush marking, sagging and flowing
41、 away from the edge of dry mouldings, and for any other defects (seenote3 to the foreword). 5.2.1.2 Undercoats Undercoats shall be tested over a primer on plywood or steel panels prepared in accordance with5.2.1.1, or on filled or recovered plywood or recovered plain steel panels prepared in accorda
42、nce with4.2.2 and4.2.3 or 4.3.2 and4.3.3 respectively. Wet abrade each primer (see note to4.2.3), using waterproof silicon carbide paper, of Cweight and not coarser than grade P220, complying with BS871, until similarly smooth surfaces free from brush marking or other defects are obtained on all pan
43、els.BS3900-A5:1991 BSI 07-1999 5 Wash the panels thoroughly with clean water, remove surplus water with a soft lint-free cloth or a sponge and washleather, and allow the panels to dry for at least 24h in a vertical position. Use one panel for each undercoat being tested and one panel similarly for t
44、he reference undercoat. Mask off (seenote) an area of approximately 0.1m 2in the form of a square at the bottom corner of each panel, remote from any moulding (seeFigure 2). Apply the reference undercoat and the test undercoat to separate panels as described in5.2.1.1. Note any differences in applic
45、ation properties. Allow the undercoat to dry for at least 24h in a vertical position and then remove the masking. NOTEThe object of masking a portion of the panels is to allow the substrates to be checked for comparability. Compare the undercoats under test with the reference undercoat, for freedom
46、from brush marking, sagging and flowing away from the edges of any mouldings, and for any other defects (seenote3 to the foreword). 5.2.1.3 Finishing paints White finishing coats shall be treated as finishing systems in accordance with5.2.2. Finishing paints shall be tested on panels prepared in acc
47、ordance with 5.2.1.2 except that no part of the primer shall be masked off. The undercoat shall be appropriate to the top coat to be applied. Before applying the finishing coat, wet abrade and dry the plain areas of the panels in the same manner as described for primers in5.2.1.2, except that the si
48、licon carbide paper used for flatting shall be not coarser than grade P280. Mask off 0.1m 2of the undercoat at the bottom corner of each panel, remote from any moulding (seeFigure 3). Apply the reference finishing paint and the finishing paint under test to separate panels as described in 5.2.1. Not
49、e any differences in application properties. Allow the finishing paints to dry for at least 24h, with the panels in a vertical position, and then remove the masking. Compare the finishing paint under test with the reference finishing paint for freedom from brush marking, sagging, flowing away from the edges of any mouldings, wrinkling, floating and any other defects (seenote3 to the foreword). 5.2.1.4 Wood varnishes Finishing varnishes shall be tested on plywood panels prepared by presealing with at least two sealer coats of a varnish similar to that u
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