WFP does a perfectly good job of sills, and if you already do a good job of cleaning your customers sills with trad methods, the sills will already be clean to begin with, so keeping them that way isn't a problem.
totaly aggree, in fact they come up fine. not a prob. macc. ;D
do you keep goose neck on to clean sills i find the goose neck a pain in the arseYou are best using an adjustable one,Gaz ;)