BS-3544-1962.pdf

BRITISH STANDARD BS 3544:1962 Incorporating Amendment Nos. 1 and 2 Methods of test for Polyvinyl acetate adhesives for wood Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 This British Standard, having been approved by the Adhesives Industry Standards Committee and endorsed by the Chairman of the Chemical Divisional Council, was published under the authority of the General Council on 28 September 1962 © BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference ADC/6 Draft for comment AB(ADC) 1764 ISBN 0 580 35083 5 Co-operating organizations The Adhesives Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Adhesive Manufacturers Association* Association of British Chemical Manufacturers Association of British Plywood and Veneer Manufacturers* Board of Trade British Carton Association British Furniture Manufacturers Federated Associations* British Gelatine a suitable device is described in Appendix B and illustrated in Figure 9. 15100× 247× -9= Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 2 © BSI 07-1999 Appendix A Preparation of test pieces for tests for resistance to sustained load A.1 a) Selection of test slips. Prepare the test slips from European beech (Fagus sylvatica) 0.125 ± 0.005 in (3.18 ± 0.13 mm) thick. The growth rings may be at any angle, from 0 to 90° inclusive, relative to the face. Both faces of the slip should be planed. The slips shall be flat and free from splits, knots, whorls and dote; the angle of inclination of the grain across the face of each test slip shall be not greater than 1 in 9, and the grain shall not be obviously inclined to the face. i) Inclination of grain ACROSS the face. The appearance of the “flower” (growth ring figure) on the face of a slip gives little indication of the straightness of grain (see Figure 3). The small rays, which are darker in colour than the surrounding wood, afford an easy means of determining grain direction. Figure 3 shows straight-grained slips and Figure 4 illustrates the maximum permissible grain inclination of 1 in 9 across the face. ii) Inclination of grain TO the face. The inclination of the grain to the face of the slip is viewed on the edges (see Figure 5) and the long lines formed by the junctions of the growth rings afford the best guide. The areas of darker ray tissue shown diagrammatically in Figure 5 should be disregarded. Immediately before the preparation of the test piece, lightly sand each slip. NOTEA suitable procedure is to give the appropriate part four double strokes parallel to the direction of the grain with a flat block to which a sheet of suitable abrasive material1) has been firmly attached. Take care to hold the block flat on the slip so that the surface is uniformly sanded and rounding of the sides of the slip is avoided. b) Moisture content. The moisture content of the slips at the time of gluing shall be 12 ± 2.5 per cent. NOTEThe specified moisture content of 12 ± 2.5 per cent corresponds with the conditions attained by wood during storage in a normally heated room in the British Isles. To determine the moisture content, accurately weigh representative samples of the wood and dry them in an oven maintained at a temperature of 105 ± 3 °C until their weight is constant. Take care to prevent change in moisture content between the cutting of the sample and the first weighing, or between removal from the oven and the subsequent weighing. where W = weight, in grammes, of sample before treatment and W1 = weight, in grammes, of dried sample. c) Construction of test pieces. i) Test slips. Prepare each test piece from three slips of beech selected as described above, 4.5 ± 0.01 in (114 ± 0.25 mm) long and 1 ± 0.01 in (25 ± 0.3 mm) wide, joined together with the adhesive under test so as to produce a 0.5 ± 0.01 in (12.5 ± 0.3 mm) overlap joint (see Figure 6). ii) Preparation of the adhesive. Prepare and use the adhesive in accordance with the instructions provided by the manufacturer. iii) Preparation of the test pieces. Prepare the test pieces under ordinary room conditions, except where otherwise directed by the manufacturer. Apply the adhesive uniformly to one of the two faces forming a joint or as prescribed by the manufacturer. Place the slips forming a joint in contact without rubbing, immediately the adhesive is applied, or after such period as may be prescribed by the manufacturer. When the test pieces have been prepared, place them immediately in a suitable clamp, a convenient form of which is shown in Figure 7. Apply sufficient pressure to ensure good contact: normally a load of approximately 50 lb (23 kg), equivalent to a pressure of 100 lbf/in2, is adequate. A convenient jig for locating the clamp and its contents is shown in Figure 8. Allow the test pieces to remain in their clamps, in ordinary room conditions, for not less than 8 hours, or as instructed by the manufacturer. 1) Glass paper complying with Grade No. 1 of BS 871, “Abrasive papers and cloths for general purposes”, is recommended. Water, per cent by weight 100 WW1() W1 -= Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 © BSI 07-19993 A.2 Conditioning of the test pieces. Release the test pieces from their clamps and place them in a conditioning atmosphere2) of 25 ± 1 °C (77 ± 2 °F) and 65 ± 2 per cent relative humidity for not less than 7 nor more than 14 days. Leave the test pieces in the conditioning atmosphere until ready for test. For the “damp” test, a further conditioning period of 7 days at 25 ± 1 °C (77 ± 2 °F) and 90 ± 2 per cent relative humidity is necessary before testing. Appendix B Timing device for sustained loading tests A suitable timing circuit for the sustained loading tests is shown in Figure 9. The basis of the arrangement is that at fixed intervals the mains voltage is applied to a power unit having a d.c. output of about 200 W. This d.c. voltage is applied across suitable contacts on each test piece arranged in series with a solenoid counting relay. Each counter clicks up one at regular intervals, therefore, until the contact in series with it has broken by the failure of the test piece. NOTEThere are a number of ways in which the apparatus may be constructed but the following has been found to be satisfactory: For regular closing of the a.c. circuit use a micro-switch operated by a sprocket wheel with 36 teeth, mounted on the spindle of a 24-hour autographic clock. The power unit may be made up of a 5 : 1 transformer together with a full-wave copper oxide rectifier. The Post Office counters are 400 ohm, ref. No. 9D. 2) A British Standard now in preparation, on “Laboratory conditioning ovens (non-injection type)” will give information on the maintenance of standard conditions by the use of saturated salt solutions. At 25 °C, a relative humidity of 65 per cent may be obtained by use of a saturated solution of sodium nitrite: the relative humidity over a saturated solution of zinc sulphate at this temperature is 88 per cent. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 4 © BSI 07-1999 Figure 2 Jig for assessing the resistance to a sustained load Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 © BSI 07-19995 Figure 3 Straight grain across face Figure 4 Grain inclination across face at maximum permissible angle Figure 5 Inclination of grain to the face Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 6 © BSI 07-1999 Figure 6 Test piece Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 © BSI 07-19997 Figure 7 Clamping device for holding three test pieces Figure 8 Jig for locating test pieces in clamp Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 8 © BSI 07-1999 Figure 9 Timing circuit for sustained loading tests on PVA adhesives Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 08:11:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3544:1962 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. 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