Surface contamination from soluble salts and residual blast media are major factors affecting the long-term performance of coatings on steel surfaces. Before the application of protective coatings, substrates must be thoroughly inspected for the presence of surface contaminants such as soluble salts, dust, oil, and grease.
Soluble salts are not visible to the naked eye and if allowed to remain on the substrate in sufficient quantities, can draw moisture through the coating causing premature coating failure from osmotic blistering or disbondment. If not identified and remediated, excessive dust particles can also reduce the adhesion of applied coatings, leading to coating failure.
Quality assurance programs benefit greatly from the regular use of determinative tests such as the Bresle Method salt contamination test (ISO 8502-6, ISO 8502-9) and Dust Tape Test (ISO 8502-3). DeFelsko offers several products to assess surface cleanliness.
Conforms to ISO 8502-3/-6/-9, US Navy PPI 63101-000, U.S. Navy NAVSEA NSI 009-32, AS 2894.6, IMO MSC.215(82), IMO MSC.244(83), SSPC Guide 15, ISO 11127-6, ASTM D4940
The PosiTector SST measures the concentration of soluble salts (salt contamination) on metal surfaces via the Bresle Method.
Conforms to ISO 8502-6/8502-9, US Navy PPI 63101-000, U.S. Navy NAVSEA NSI 009-32, AS 3894.6, IMO MSC.215(82), IMO MSC.244(83), SSPC Guide 15, ISO 11127-6, ASTM D4940
The PosiTest DT assesses the quantity and size of dust particles on blast cleaned surfaces. Optional spring-loaded Dust Tape Roller available to apply constant force as recommended by ISO 8502-3.
Conforms to ISO 8502-3, AS 3894.6, US Navy PPI 63101-000
Steel surfaces are frequently cleaned by abrasive impact prior to the application of protective coatings. This process removes previous coatings and roughens the surface to improve coating adhesion. Contamination from the atmosphere or abrasive blasting process can result in deposits of salts, dust, oils, and/or greases—which can detrimentally affect the adhesion properties of the coating system.
Contamination testing can be used to assess the effectiveness of mitigation efforts and to identify best remediation methods. By understanding the level of contamination on a surface, inspectors can ensure that coatings are applied properly and will last for their intended lifespan.
A salt contamination test, as described by standards such as ISO 8502-6 and ISO 8502-9, is used to extract water soluble salts from a blasted steel substrate and determine their concentration. If within acceptable levels, no further action is generally required. If not within acceptable levels, cleaning methods (water/steam/alkaline cleaning) may be used, as detailed in ISO 12944-4.
The Bresle method samples a surface by means of “surface extraction”. Put simply, this method involves placing a volume of purified water in a chamber (a Bresle method patch) against a steel surface. The water dissolves the soluble salts present on the surface, raising the electrical conductivity of the water. This extracted solution is then measured using a conductivity meter (conductometer) such as the PosiTector SST. The measured increase in conductivity establishes the concentration of soluble salts.
Read the article, “Measuring Soluble Salts in Accordance with ISO 8502-6 and ISO 8502-9—the Bresle Method”.
Reusable Bresle patch with Standard or Flexible magnetic ring—lowest per test cost
Learn More
Latex Bresle Test patch with easy-open tabs and low-tack adhesive for easy removal
Learn MoreThe Bresle method salt contamination test is performed in 3 easy steps when using the PosiTector SST.
The Dust Tape Test is a test procedure, defined by ISO 8502-3, used to assess the dust quantity rating and dust size on steel surfaces prior to the application of paint and coatings. Dust is often present on steel surfaces after blast cleaning in the form of remnants of the blast media and deposits in the environment and atmosphere.
The Dust Tape Test provides a basis for rating the dust contamination of blasted steel surfaces to determine if remedial steps, such as those defined by ISO 8504-2, should be taken.
The Dust Tape Test is performed by applying a length of tape onto a blasted surface, removing it, then visually assessing the tape for the size and quantity of dust particles compared to the description of the pictorial references found in ISO 8502-3.
No. The PosiTest DT Dust Tape Roller is an optional accessory with a calibrated roller used for applying force as recommended by ISO 8502-3. It can be used to improve the accuracy of the test method.
The following standards are often used to determine the surface cleanliness of a substrate before painting:
ISO 8501-1 provides instructions for visually assessing blast, hand/power tool, and flame cleaned steel after the removal of coatings.*
ISO 8501-2 provides guidance similar to ISO 8501-1, but rather than for wholly uncoated steel, ISO 8501-2 is a visual assessment for localized removal of paint.*
ISO 8501-3 offers guidance for visually assessing and grading steel surfaces with imperfections, including welded and fabricated surfaces, to make them suitable for the application of paints and coatings.*
After the removal (or partial removal) of water-soluble contaminants such as salt, rust, previous paint coatings, and foreign matter; it is necessary to determine the level of cleanliness of the steel substrate. ISO 8501-4 specifies “Preparation Grades” defined by written descriptions and photographic representative examples.*
ISO 8502-1 is a test method used to determine the soluble iron corrosion products on steel surfaces blast-cleaned to Sa 2 ½ (see ISO 8501-1) or better. This method tests for iron (ii) ions via colorimetric reaction.*
This laboratory method for determining the chloride content of steel substrates (coated or uncoated) details a chloride sampling method but also mentions that ISO 8502-6 (the Bresle method) may be used.*
Related product: PosiTest DT
The ISO 8502-3 Dust Tape Test is performed by pressing a length of tape onto a blasted surface and then visually assessing the tape for the size and quantity of dust particles using the pictorial references found in the standard.*
Related product: PosiTector DPM, PosiTector DPM L
ISO 8502-4 provides a method to give guidance on the estimation of the probability of condensation forming on a surface to be painted.*
ISO 8502-5 details a field test to measure chloride ions on steel and other painted surfaces before and after cleaning.
Related Products: PosiTector SST, Bresle Patches
Related Article: “Measuring Soluble Salts in Accordance with ISO 8502-6 and ISO 8502-9—the Bresle Method”
Related Video: “How to Measure Salt Contamination with the PosiTector SST Soluble Salt Tester”
ISO 8502-6 details the Bresle method as a means of extracting water soluble contaminants from a steel surface using adhesive patches or sleeves for analysis.*
Related Products: PosiTector SST, Bresle Patches
Related Article: “Measuring Soluble Salts in Accordance with ISO 8502-6 and ISO 8502-9—the Bresle Method”
Related Video: “How to Measure Salt Contamination with the PosiTector SST Soluble Salt Tester”
ISO 8502-9 specifies a method of determining the surface density of water-soluble salts on steel surfaces by use of a conductometric instrument, such as the PosiTector SST. The surface extraction methods are detailed in ISO 8502-6.*
ISO 8502-15 is similar to ISO 8502-6 (the Bresle method) as a method of extracting surface contaminants using patches or sleeves. Instead of using water as a solvent (ISO 8502-6), this method uses a mildly acidic solution.*
