Spoilage of paint in the container is often related to the use of contaminated raw materials, water (particularly recycled washwater), vessels, piping, and equipment in the manufacturing plant. There is a need for a simple method to determine the presence or absence of microorganisms in plants that manufacture paints and coatings. Such a determination enables the manufacturer to establish the point of contamination (that is, raw materials or problem housekeeping areas in the plant) to help in solving the spoilage problem.

Note 1-Some contamination in plant areas is to be expected, since microorganisms are ubiquitous and cannot generally be eliminated practically (it is what an in-can preservative is supposed to control). Excessive levels of contamination or contaminated raw materials can exceed the capability of the preservative. If you have excessive contamination in the plant, there are methods for decontamination including steam, preservatives, bleach, etc. These should be discussed with your biocide supplier and used with care. Recovery of spoiled or contaminated products is often not feasible, so an adequate level of the appropriate biocide in conjunction with good plant housekeeping practices are essential. Your biocide supplier can also help here.

This test method may be used by persons without basic microbiological training, but some training on aseptic techniques would be recommended.

Note 2-The reliability of the results obtained from this test method is extremely dependent on the techniques employed. Improper techniques can result in a sterile sample appearing to be contaminated, and even worse, a contaminated sample appearing to be sterile (see also 5.1). It is recommended that you consult with your biocide supplier, raw material supplier, or an independent testing laboratory to confirm questionable results.