This standard is an equivalent adoption of international standard "Paints and Varnishes-Determination of Resistance to Liquids" (ISO 2812-1974).
1 Subject Content and Application Scope
This standard specifies three test methods for determining the resistance of single coating or multi-coating of paints and varnishes or painting test pieces to the action of liquids, the test methods are immersion method, absorbent medium method and spotting method. The method to be used depends on the particular requirements and coating resistance of the test material.
2 Normative References
GB 912 Plain Carbon Structural Steel and Low Alloy Structural Steel Sheets Technical Conditions
GB 1727 Methods of Producing Films of Paints, Varnishes, Lacquers and Related Products on Test Panels
GB 1764 Methods of Test for Measurement of Dry Film Thickness of Paints
GB 2520 Cold-reduced Electrolytic Tinplate
GB 3186 Sampling Paint Products
GB 3880 Aluminum and Aluminum Alloy Rolled Sheet
GB 9271 Paints and Varnishes Standard Panels for Testing
3 Sampling
It shall be carried out according to the requirements specified in GB 3186.
4 Test Pieces
4.1 Material and dimension
4.1.1 Test panel
Unless otherwise specified or agreed, the test panels shall be tinplate (GB 2520): 50mm×120mm×0.2~0.3mm, steel plate (GB 912), plain carbon cold rolled steel: 50mm×120mm×0.45~0.55mm, aluminum plate (GB 3880 LY12): 50mm×120mm×1~2mm .
4.1.2 Test rod (for immersion method only)
One end of each rod shall be rounded to approximate the radius of the rod itself and the other end shall have hole or ring. Unless otherwise specified, the rods shall be of steel or aluminum. Suitable dimensions for the rods are φ15mm×150mm diameter.
4.2 Preparation and coating
4.2.1 Test panel
Unless otherwise specified or agreed, the test panels shall be prepared and coated in accordance with those specified in GB 9271. Generally, it is necessary for the back of the panel to be coated with a suitable protective paint or product under test, the edges of the test panel shall be sealed by suitable means.
4.2.2 Test rod
Unless otherwise specified or agreed, the test rods shall be prepared and coated in accordance with those specified in GB 1727.
4.2.3 Drying the test pieces
The coated test pieces shall be dried (or stoved and placed) for the specified time and, unless otherwise agreed, shall be conditioned at a temperature of 23±2℃ and a relative humidity of 50%±5%. The disposal time shall be in accordance with those specified in product standard or GB 1727. Generally, the minimum time is 16h (except drying paint).4.2.4 Determinate the thickness of coating
It shall be determined according to those specified in GB 1764.
5 Test Procedure - Method A (Immersion Method)
5.1 Liquid materials for testing
The test liquids shall be those specified in product standard.
5.2 Test temperature
The test shall be carried out at a temperature of 23±2℃ unless otherwise specified.
5.3 Test precautions
5.3.1 It is preferable to immerse the test pieces individually in the test liquid, particularly when using liquids of high electrical conductivity in which electrolytic effects could be of some importance.
5.3.2 In certain cases, however, it may be more convenient to immerse several test pieces in a single tank; in these cases, the nature of the test pieces shall be identical and every precaution shall be taken to ensure that the test liquid is unaffected by the test pieces.
5.3.3 The test pieces shall be at least 30mm from the sides of the tank and if several pieces are immersed in the same tank they shall be at least 30mm apart. The test pieces shall be electrically insulated from their supports.
5.4 Procedure A: using a single-phase liquid
5.4.1 Place a sufficient amount of the liquid in a suitable vessel to completely or partially (2/3) immerse the test piece (rod or panel) as specified. Immerse the test piece in an approximately vertical position using suitable supports if necessary.
5.4.2 Cover the container for the duration of the test to minimize the loss of liquid by evaporation or splashing.
5.4.3 If specified, aerate, agitate or circulate the liquid. Aeration shall be carried out by means of a slow stream of air free from oil and grease. If specified, make good any liquid losses by the addition of the test liquid or distilled water at suitable intervals in order to maintain the original volume or concentration.
5.4.4 At the end of the specified immersion period, wash the test piece thoroughly in running water if an aqueous test solution has been used or with a solvent known to be non-injurious to the coating if a non-aqueous test liquid has been used. Remove any residual liquid from the surface by dabbing with a suitable absorbent paper or cloth, and examine the test piece immediately for any signs of deterioration of the coating, if necessary comparing with an identically prepared, but un-immersed, test piece. Examination and comparison shall be repeated after a recovery period if so specified.
5.4.5 If it is required to examine the substrate for signs of attack, remove the coating by the specified method.
5.5 Procedure B: using a two-phase liquid
5.5.1 Insert the coated test piece into a suitable vessel so that it rests by means of suitable supports in an approximately vertical position and, in the case of panels, the broadside is horizontal.
5.5.2 Prepare each of test liquid immediately before use.
5.5.3 Carefully pour the liquid of higher density down the side of the vessel until the test piece (rod or panel) is immersed to a depth of 60mm, unless otherwise specified. Care must be taken not to contaminate the test piece above this level.
5.5.4 Add the second liquid in the same manner until the test piece is immersed totally, unless otherwise specified. Cover the vessel and allow to stand, without agitation.
5.5.5 At the end of the specified immersion period remove the test piece from the test liquids, remove any test liquid from the surface by dabbing with a suitable absorbent paper or cloth, and examine the test piece immediately for any signs of deterioration of the coating in contact with each liquid phase. Compare it if necessary with an identically prepared but un-immersed test piece. Examination and comparison shall be repeated after a recovery period if so specified.
5.5.6 Specimens must not be removed for intermediate examination without subsequent cleaning and repetition of the immersion procedure (see Articles 5.5.1, 5.5.2 and 5.5.3).
5.5.7 If it is required to examine the substrate for signs of attack, remove the coating by the specified method.
1 Subject Content and Application Scope
2 Normative References
3 Sampling
4 Test Pieces
5 Test Procedure - Method A (Immersion Method)
6 Test Procedure - Method B (Using an Absorbent Medium)
7 Test Procedure - Method C (Spotting Method)
8 Test Report
Additional Information
