BRITISH STANDARD AUTOMOBILE SERIES BS AU 148 2 1969 Methods of test for motor vehicle paints — Part 2 Resistance to continuous salt spray UDC 629 113 667 613 620 193 272 BS AU 148 2 1969 This British[.]
BRITISH STANDARD AUTOMOBILE SERIES Methods of test for motor vehicle paints — Part 2: Resistance to continuous salt spray UD C 62 1 : 667 61 : 62 BS AU 48-2:1 969 BS AU 48-2:1 969 This Britis h S tandard, having b een ap p roved b y the Automob ile I ndus try S tandards C ommittee, was p ub lis hed under the authority of the E xecutive Board of the Amendments issued since publication Ins titution on March 69 © BS I - 00 The following BS I reference relates to the work on this s tandard: C om mittee reference AUE /- ISBN 80 05 38 Amd No D ate C omments BS AU 48-2:1 969 Contents Page Foreword ii S cop e C orrelation and limitations of tes t S up p lementary information Tes t s p ecimens Tes t equip ment Pos ition of s p ecimens during tes t Tes t s olution Air s up p ly Tes t conditions 10 Procedure 11 Rep ort of tes t Figure — S alt s p ray cab inet for tes t condition T2 Figure — S alt s p ray j et for tes t condition T2 5 Figure — S alt s p ray cab inet for tes t condition T3 Figure — Walk- in chamb er, m b y m and up ward in overall s ize for test condition T3 © BS I - 00 i BS AU 48-2:1 969 Foreword This Part of this British Standard has been prepared under the authority of the Automobile Industry Standards Committee and is based on Information Sheet No NM – 5X of the Society of Motor Manufacturers and Traders Ltd (SMMT) Tests for paints for general purposes are given in BS 3900 1) and, wherever possible, reference has been made to that standard 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 1) BS 3900, “ Methods of test for paints ” Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages to 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 ii © BSI 02- 2000 BS AU 48-2:1 969 Scope Test specimens 1 This Part of this British Standard describes a 4.1 Specimens for test will generally be panels procedure for determining the resistance of paint prepared and coated with the materials to be tested, films to a continuous salt fog environment Two test but for some purposes (for example quality control conditions, differing only in temperature of tests) painted components, or suitable portions of operation, are given: them, may be required Test condition T25: temperature 25 ± ° C Where components are to be tested it is important to Test condition T35: temperature 35 ± ° C select samples which are free from accidental The standard does not prescribe periods of test, nor the interpretation to be given to the results Correlation and limitations of test In order to obtain good reproducibility between laboratories, it is necessary to observe the recommended operating conditions, correct spacing of and positioning of specimens and to ensure suitable siting of equipment Suitable forms of equipment which may be used to obtain the required conditions are referred in 5.1 Results from other designs of equipment have been found to correlate damage If this is impracticable, or if the test portion is cut from a large sample, damaged areas or cut edges etc shall be covered with a good protective coating 4.2 Preparation and coating of test panels 4.2.1 Panels, 50 mm × 00 mm or other convenient size, specified and pretreated in accordance with the requirements of BS 3900- A3 2) (note particularly Clause 2.2 ) shall be coated in accordance with the requirements of BS 3900- A4 2) with the paint system to be tested Normally, steel panels are used, but it may be appropriate to use other substrates and such equipment may be used, subj ect to 4.2.2 The panels shall be aged, under normal agreement between the purchaser and the supplier laboratory conditions, for days, unless otherwise agreed Supplementary information 4.2.3 If the specimen panel is not coated on all The following supplementary information, together with reference to appropriate standards where applicable, is required in order to carry out the tests surfaces with the material under test, coat the back and edges of the panels with a good protective coating 4.2.4 Unless otherwise agreed, the test panel shall described in this standard: be damaged with a scriber by making longitudinal ) Type of coating or coatings scratches, mm wide, through to the metal 2) Nature of substrate and method of substrate They shall extend at least preparation & of the length of the panel and shall be positioned centrally in each 3) Method of application of test coating or vertical half The scriber used shall be made from coatings to substrate mild steel mm thick and shaped to give a chisel 4) Thickness and/or weight of coating, or of edge capable of making the required scratches individual coatings in the case of multicoat Test equipment systems 5) Duration and conditions of drying of the coated The equipment required consists of a chamber, a specimen (or condition of stoving, if applicable) salt solution reservoir, a supply of suitably before testing conditioned compressed air, one or more atomizing 6) Required duration of test and test conditions nozzles, specimen supports, provision for heating the chamber and necessary means of control The (T25 or T35) 7) How inspection of the tested coating is to be made and what characteristics are to be considered in evaluating its resistance to this size and detailed construction of the equipment are optional, provided the conditions obtained meet the requirements of this test It is important that the chamber shall be insulated test to avoid temperature gradients, particularly with test condition T35 With small cabinets, this is conveniently effected by means of a double skin construction, incorporating a water j acket for temperature control 2) BS 3900, “ Methods of test for paints Preparation of panels prior to painting Notes for guidance on paint application Part A3, “ Part A4, “ © BSI 02- 2000 ”, ”, ” BS AU 48-2:1 969 A suitable form of test equipment for test Suitable materials for the construction or coating of condition T25 is shown in Figure and Figure racks or supports are glass, rubber, certain plastics Equipment suitable for test condition T35 is materials or suitably coated wood Bare metals shall illustrated in Figure and Figure not be used Drops of solution which fall from the specimens 6.3 Each specimen shall be placed so as to permit shall not be returned to the solution reservoir for free settling of fog on all specimens respraying 6.4 Salt solution from one specimen shall not be Materials of construction shall be such that they allowed to drip on to any other specimen will not affect the corrosiveness of fog Glass, rubber or certain plastics materials (or linings thereof) are suitable Test solution The test solution shall be prepared as follows: The spray from the atomizing nozzle, or nozzles, shall be prevented from impinging on the test specimens by means of suitable baffles The solution condensing on the baffles may be returned to the salt solution reservoir; this can effect a substantial economy in rate of consumption of the solution Adj ustable baffles are of assistance in obtaining a uniform collection rate throughout the test zone of the chamber (see 9.2 ) Dissolve 50 ± g sodium chloride, complying with BS 908 “ Vacuum salt for butter and cheese making ”, in each litre of distilled or de- ionized water or water containing less than 00 p p m of total dissolved solids and substantially free from dissolved heavy metals, particularly nickel, copper and iron The pH of the solution shall be such that when atomized under the test conditions, the collected solution (see 9.2 ) will have a pH – 5 The equipment shall be sited so as to be in diffused light and away from radiators or other sources of heat, and draughts, in order to facilitate temperature control 8.1 The compressed air supply to the nozzle or nozzles for atomizing the salt solution shall be free Position of specimens during test 6.1 Unless otherwise specified, the specimen shall be supported so that the test surfaces are from oil, oil vapour and dirt and maintained between 67 bar and 72 bar 4) 8.2 The air shall be saturated with moisture by means of a water wash or humidifying tower, after between ° and 30 ° from the vertical and preferably parallel to the principal direction of horizontal flow of fog through the chamber In the case of components of complicated shape, several specimens may be required, so that all significant surfaces are exposed substantially in this way Alternatively, by agreement, the component may be placed in the position in which it will be assembled in service In all cases, the test surface shall be at least 30 mm from any other specimen and at least 35 mm from any wall of the chamber It is recommended that, to obtain reasonable capacity to ensure even dispersion of fog This may be achieved, when testing flat panels, by 3) suitable filtration It is preferable to operate the tower at temperatures well above the chamber temperature to ensure wet fog, to offset heat losses and to maintain the required temperature in the chamber The tower temperature should be adj usted so that both the collection rate (see 9.2 ) and composition of collected fog (see Clause ) are kept within the specified limits For guidance, the following table shows the tower temperatures at different air pressures required to offset the cooling effect of expansion at the nozzle or nozzles to reproducibility of test, the cabinet be run at full introducing blanks made of inert material Air supply atmospheric pressure for test condition T35: Air pressure (bar) 1.0 1.1 1.2 Temperature (° C) 45 47 48 49 of the same dimensions The position of panels in the cabinet should be varied, throughout the test period, every 24 hours The nozzle or nozzles may be operated intermittently by means of a suitable timer and relay actuating a solenoid valve in the air supply, providing that the fog is maintained continuously 6.2 The specimens shall not contact any material (e g air pressure s on, s off) This provides capable of acting as a wick means of adj usting the collection rate (see 9.2 ) and it also ensures a more consistent fog distribution with minimal directional effects 3) 4) An example of a suitable material is “Perspex” bar = N/m © BSI 02- 2000 BS AU 48-2:1 969 3) Examine the surface immediately for corrosion Test conditions 9.1 Temperature The exposure zone of the test chamber shall be maintained at the following of the substrate, spread of corrosion and loss of adhesion at the scribed lines, blistering, softening of the paint, or other signs of deterioration Then temperatures: immediately after, remove a 50 mm × 50 mm Test condition T25: 25 ± ° C strip of paint from the test face with a Test condition T35: 35 ± ° C non- corrosive paint remover complying with 9.2 Atomization and quantity of fog At least two clean fog collectors shall be placed in the exposure zone in the proximity of the test specimens, one near to a nozzle and another as far as possible from a nozzle They shall be positioned so that no test solution falling from the test specimens is collected The fog shall be such that for each 000 mm of BS 3761 5) Examine the exposed substrate for signs of corrosion To protect the panel for reference purposes, the exposed area shall be protected by a suitable transparent lacquer or tape 4) Unless otherwise agreed, any general loss of adhesion of the paint film to the substrate, or horizontal collecting area there will be collected, in between coats, shall be determined by the cross each collector, from – ml of solution per hour, hatch and/or tape adhesion test (as Part determined over an operating period of at least h The collected spray solution shall contain 50 ± g/l of sodium chloride (specific gravity 0255 – 0400 at 25 ° C) and pH shall 6) of this standard) within – of removing the specimen from the cabinet 1 Report of test be – The test report shall contain at least the following NOTE information: Standard laboratory glass funnels or dishes with a diameter of 00 mm have a horizontal area of 000 mm ) Identification of material under test Procedure 2) The product specification and any other The following procedure shall be carried out: (see Clause ) 5) 6) supplementary information required for the test ) Expose the specimen in the cabinet for the 3) Any deviation, by agreement or otherwise, specified period from the standard test procedure 2) Remove the specimen, wash in cold running 4) The results of the test in terms of the specified water, and dry off requirements BS 3761 , “ Water rinsable and solvent rinsable paint removers” Flexibility and adhesion” BS AU 48- 3, “ © BSI 02- 2000 BS AU 48-2:1 969 (All dimensions in millimetres) Figure — Salt spray cabinet for test condition T25 © BSI 02- 2000 (Not to scale) Figure — Salt spray j et for test condition T25 BS AU 48-2 :1 969 © BSI 02- 2000 BS AU 48-2:1 969 F Angle of lid, 90 ° to 25 ° Thermometer and thermostat for controlling heater (Item No 8) in base Automatic water levelling device Humidifying tower Automatic temperature regulator for controlling heater (Item No 5) Immersion heater, non- rusting Air inlet, multiple openings Air tube to spray nozzle R Strip heater in base Hinged top, hydraulically operated, or counterbalanced 10 Brackets for rods supporting specimens, or test table 11 Internal reservoir 12 Spray nozzle above reservoir, suitably designed, located, and baffled 2A Spray nozzle housed in dispersion tower located preferably in centre of cabinet 13 14 Water seal Combination drain and exhaust Exhaust at opposite side of test space from spray nozzle (Item 2) , but preferably in combination with drain, waste trap, and forced draft waste pipe (Items 6, 7, and 9) 16 Complete separation between forced draft waste pipe (Item 7) and combination drain and exhaust (Items and 9) to avoid undesirable suction or back pressure 17 Forced draft waste pipe 18 Automatic levelling device for reservoir 10 Waste trap 20 Air space or water j acket 21 Test table or rack, well below roof area Figure — Salt spray cabinet for test condition T35 © BSI 02- 2000 BS AU 8-2 : 969 NOTE The controls are the same, in general, as for the laboratory cabinet (Figure 3) , but are sized to care for the larger cube The chamber has the following features: ) Heavy insulation, 2) Refrigeration door with drip rail, or pressure door with drip rail, inward sloping sill, 3) Low temperature auxiliary heater, and 4) Duck boards on floor, with floor sloped to combination drain and air exhaust Figure — Walk-in chamb e r, m b y m and up ward in overall size for te st condition T3 © BSI 02- 2000 BS AU 48-2:1 969 BSI — British Standards Institution BS I is the indep 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