Preventing Premature Coating Failure by Surface Contamination
Coating failures can occur for a multitude of reasons, but the most common failures are caused by insufficient surface preparation. This can lead to adhesion failure where a paint or coating delaminates from the coating or surface below. Not properly preparing the surface prior to coating can leave surface contamination such as soluble salts, dust, or dirt making the coating application fail by blistering or peeling. The first step of prevention is determination.
Determination of Surface Contamination
The two basic steps for determining surface contamination are testing by extraction and analysis. Testing is done with such products as test patches, or sleeves.
- Test patches measure water soluble salts on steel. If they aren't 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.
- Test Sleeves are an easy to use, efficient field test and were developed to prevent outside and cross contamination. They offer consistent, safe, and reliable testing results for contamination.
Both types are used to extract or measure and analyze the soluble salt content on a substrate.
When to Incorporate Salt Remover
If the content is above the acceptable range specified, you would need to incorporate the use of a salt remover or maintenance wash to remove the salts, then retest prior to application. The wash reduces the content of dirt and salt. It contains no volatile organic compounds (VOC), is non-flammable and also biodegradable. Maintenance wash is recommended for use anywhere that these contaminants are identified and need to be removed prior to the coating process.
Causes of other forms of coating failures
- Environmental Conditions such as improper temperature, excessive moisture or air movement causing blistering, wetting problems, solvent popping, and cratering.
- Improper Application Techniques such as inadequate or excessive thickness of the applied coating causing orange peeling, sagging, or running.
- Improper Formulation such as improper mixing of components causing chalking, checking, cracking, and erosion.
Summary: Coating failure threatens the life span of equipment and facilities. Recognizing the causes of coating failure and seeking ways to improve coating performance helps to cut both maintenance and costs. The best way to keep your coating from failing is to prevent these defects in the first place. Test, analyze, and clean your substrate prior to coating to prevent premature coating failure and keep your costs in line. Ensure proper surface preparation by incorporating salt remover when warranted into your procedure. By following this process, you can ensure that you surface is clean of dirt and salts that cause premature coating failure.
Visit our Protective Coatings Industry Page for Surface Preparation and Protective Coating Test Instruments.