Different types of 'boosters' can be added to water-based raw materials and coatings to complement biocidal active ingredients. Here we investigate via microbiological challenge tests what benefits they offer, if any, with regards to an extension of the microbial spectrum of activity, speed of kill and length of protection afforded. We also look at any positive consequences with regards to the labelling thresholds under existing European legislation. The introduction in 1998 of the Biocidal Products Directive (BPD - 98/8/EC) marked the beginning of the registration for biocidal active ingredients in Europe. Initially, an active ...