Surface Contamination Test

What is Surface Contamination Test?

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

Surface contaminants are the impurities that bond or settle on metal surfaces and affect the physical and sometimes chemical properties of the metal, as well as the coatings. Surface contaminants may be a result of a manufacturing process, the environment, or part handling. Surface contaminants affect the adhesion of coatings and paints, and may interfere with the protective features of the coating.

Some contaminants may react with metal to create initiation points for corrosion, or cause degradation of the coating protection, hence leading to a shorter lifespan of the protection method.

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.

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. And also many cases 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 preparation. 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.

Therefore we provided variety type of contamination test for meet client and jobs requirement:

Pre-treatment Test Kit
TQC Bresle Test Kit / Chloride Test Kit
TQC Dust Test Kit
Positector SST
Positector Abrasive Test Kit
Chloride, Sulfate and Nitrate Test Kit
ChlorTest A
ChlorTest Kit
ChlorTes W

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