Strategies to minimise soiling and biofouling of exterior coatings

Dr. Anders Larsson, YKI, Institute for Surface Chemistry, Sweden

 

Contamination of painted surfaces by non-living material such as dirt and soil as well as by living material such as mould and mildew are aesthetically unpleasing and in some cases cause hygienic problems and health hazards. In this talk we will begin by outlining the main sources of dirt and outline how micro-organisms adsorb to surfaces. Even though the focus of the talk will be directed towards decorative coatings experiences from other fields such as marine and medical coatings will also be presented. We will present different strategies to avoid or minimise mould/mildew establishing themselves and grow in films of paints and coatings. We can at least distinguish 5 different groups of useful strategies:

(1) Avoid or minimise pick up and adhesion to the coating,

(2) Depolymerise microorganisms adhesion glues,

(3) Self-cleaning of the coating using UV light and/or rain/moisture,

(4) Minimising transport of nutrients from substrate and paints to mould/mildew,

(5) Controlled release of biocides/algicides/fungicides to kill mould/mildew over long time periods.

We will outline the basic idea for each strategy and discuss possibilities and limitations of them. We believe that by choosing the right strategy/strategies the coatings can be kept clean over extended periods of time.