Meaning and use

3.1 Microbial growth is the main cause of paint film discoloration and deterioration. This guide describes the techniques used to distinguish fungi and algae from other surface contaminants.

3.2 Recoating a surface contaminated with fungus or algae usually results in a more rapid infestation of the new paint than repainting a surface that has been removed from fungal or algal growth. In addition, poor adhesion, staining/bleeding, and many other problems may result. This guide describes ways to remove fungal or algal growth before repainting.

Note 1: It is important to read and follow all steps and notes. In particular, the washing steps outlined in 5.2.2 and 5.2.4 need to be carried out completely, as residual sodium hypochlorite (bleach) can cause many of the same problems, or even lose coloring after repainting, and residual phosphate detergents can further promote fungal and algal growth.

Note 2: This procedure is suitable for recoating surfaces. Reports of using this procedure to remove fungi and algae without recoating need to include a warning about the adverse effects of bleach on the coating. The oxidation of bleach will reduce the performance of the film, especially the “bleaching” (color loss) in the film containing organic pigments (such as quinacridone, etc.), the reduction of gloss, powder, etc. Small patches need to be tested before using this program for this purpose.

ASTM D4610-1998 Standard Guide for Determining the Growth and Removal of Microorganisms (Fungi or Algae) on Paints and Related Coatings

Step 1: Scope

1.1 This guide describes techniques for determining the presence of fungal or algal growth on paints and related coatings, and methods for removing such growth prior to recoating.

1.2 Values expressed in SI units shall be considered standard. The values given in parentheses are for reference only.

1.3 This standard is not intended to address all safety concerns, if any, associated with its use. It is the responsibility of users of this standard to establish appropriate safety, health and environmental practices and to determine the applicability of regulatory restrictions prior to use.

1.4 This international standard is based on internationally recognized standardization principles established in the “Decision on Principles for the Development of International Standards, Guidelines and Recommendations” issued by the Committee on Technical Barriers to Trade (TBT) of the World Trade Organization.