Application Of Epoxy Systems

 
 

 

The most critical aspects in the use of epoxy systems are proper surface preparation and mixing in ratios specified by manufacturer's instructions.

The general directions for surface preparation always require that surfaces be clean, dry, and free of oil, dust, efflorescence, rust and loose or flaking paint. Problems arise when surfaces appear to be clean, but are actually unsatisfactory for epoxy application.

New concrete surfaces may require only a washing with a 10% muriatic acid solution and then a thorough rinsing. Old surfaces are the the troublemakers. Whether any curing compounds or sealers have been used, what types of chemicals it has subjected to and how sound the surface is, must be determined. When concrete has been subjected to certain chemicals or sugars, it may appear to be sound when it is actually quite soft.

If old coatings are present on the concrete, but are in good condition, they must be identified. For example, if a solvent based coating is put over an old alkyd or rubber-based coating, there is a good chance of a failure because of solvent attack. Even 100 percent solids epoxy systems can lift old coatings from the surface. Epoxies have excellent adhesion to these coatings, but the tension produced in curing and in use lifts them. Normally the best way to prepare these surfaces is to scarify or sandblast.

Oil and chemical soaked surfaces, are difficult to clean with conventional methods. Cleaning with solvents, or mechanical abrading (scarifying) the surface is the best method. When a concrete surface has been saturated with chemicals, specific recommendations for preparation should come the manufacturer.

Steel surfaces must be cleaning of all oil, rust, mill scale and old coatings. This cleaning is best achieved by sandblasting or mechanically abrading the surface. If there is any doubt about conditions on any surface, a sample placement should be applied.

Application

When selecting an epoxy system, it is important to relate the type of surface it will be applied to, the traffic it will be subjected to, and the types of chemicals and temperatures it will be exposed to both during application and final use.

 

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