Steel when blast-cleaned can be contaminated by water-soluble salts and corrosion products. These compounds are almost colourless and are localized at the lowest point of the rust pits. If they are not removed prior to painting, chemical reactions can result in blister formation and accumulations of rust that destroy the adhesion between the substrate and the applied protective coating. This contamination can be tested quickly and easily using the Bresle Test.
Easy to use, pour 10mls of distilled water into the beaker and determine the conductivity using the Conductivity Meter. Take a Bresle Patch and apply to the test surface. Fill the syringe with 2.5mls of test water and insert through the adhesive foam into the test chamber. Inject the contents, then extract back into the syringe. Repeat ten cycles of injecting and extracting, then transfer the test water back into the beaker. Measure the test water with the Conductivity Meter and deduct the initial conductivity reading from the result. Multiply the readings by 0.4 to give the quantity of salts in ug/cm2 also known as ppm, or by 4 for the quantity of salts ug/m2 . |
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The maximum permissible surface density of salts on the steel surface prior to surface treatment depends on the type of paint to be applied and what the finished material or product is to be used for. Surface treatment specifications must, therefore, state the highest permissible surface density of salts for each particular application.
When high adhesion strength patches are required for testing on very corroded or coarse-grade blasted steel, the Bresle Patches Plus are available as an alternative to the standard Bresle patches.
Additional packs of Bresle Patches can be purchased to carry out further tests using this kit.
Supplied in a Industrial Foam-Filled Carrying Case with 50 Bresle Patches, 50 Bresle Patches Plus, Conductivity Meter, Calibration Solution, 3 x 5ml Syringes, 25ml Beaker and 500ml deionised Water.
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