Biocide-free silicone antifouling paint tops European study

A Chalmers University of Technology-led study has found that a biocide-free silicone antifouling paint performed best against hull fouling when compared with six other coatings in Swedish, Danish and French coastal waters.

The research tested seven antifouling paints on panels submerged for up to six months at Tjärnö in Sweden, Hundested in Denmark and Arcachon Bay in France. The locations were chosen to reflect different marine conditions, with fouling levels and dominant organisms varying between sea areas.

The paints tested included five cuprous oxide coatings with copper content ranging from 6 to 32 weight percent, one biocide-free silicone coating and one copper-free coating containing tralopyril and zinc pyrithione.

According to the study, the silicone-based biocide-free paint was the most effective overall, followed closely by the coating containing tralopyril. Among the copper-based paints, copper content was not found to be the deciding factor, with lower-copper coatings performing at broadly similar levels to those with higher copper content.

The researchers also assessed environmental impact. The silicone coating was not included in the biocide risk assessment because it does not contain biocides. Of the biocidal paints assessed, none met today’s environmental risk criteria, although lower-copper coatings fell below limit values in French waters.

The study found the tralopyril-based paint, which is marketed as environmentally friendly in some EU countries, had the highest environmental risk.