Surface Contamination Test

Surface Contamination Test

Case histories indicate that non-visible surface contamination may result in rapid coating failure. Contaminants may be assumed to be presents on any steel surface. Even new steel may be contaminated at the origin or during transport or installation. Therefore, any steel surface to be coated requires cleaning followed by testing for non-visible contamination.

Non-visible contamination may be detected by allowing the just-cleaned surface to rust. If a uniform sandy rust results the surface may be free of Iron Salts and chlorides that would otherwise produce dark or black areas.

Other chemical and simple physical tests are also described and evaluated. Remediation of positive test results are discussed.  Reagents, materials, tools, procedures and results are detailed.

Surface contamination test use for detect the clean and well prepared surface also crucial for a successful coating performance.

The pre-treatment process of an industrial coating job often consumes more time and budget than the actual paint application itself.

Surface preparation

There are various methods and systems to prepare a surface prior to the coating application. Depending on the project and job specifications one could choose for hand cleaning like brushing, grinding or using needle hammers. Often grit blasting is utilised or shot blasting in automatic line for example. If no anchor pattern is required or already in place (ultra) high pressure water jetting, chemical cleaning or a simple wash down might be the solution.

Although it seems quite obvious often the parameters cleanliness and profile are mixed up.

Cleanliness is providing information about the level of contaminants which are left on the surface. This contamination could be (blast) dust, soluble salts like chlorides, old paint residues, oil and fat, (flash) rust, mil scale, condensation and moisture, amines, etc..

Surface contamination can be caused in many different ways like insufficient cleaning, residue left after (acid) rain showers, sea salt left on the surface in maritime environments, soluble salts introduced by contaminated recycled blasting media and many others.

Therefore it is important to check for surface cleanliness at the right moment in the process. It is necessary to check the levels of cleanliness after the surface prep but keep in mind during the “open time” (which varies from hours to days) of the steel new contamination can be introduced when the work is insufficiently shielded.

PT. CUANLI provided variety type of contamination test for meet client requirement:

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