Thanks for all your help. I don't think it is overwicked as it would drown if I went smaller. I actually don't really like working with CB advanced as I have a lot more troubles than with 415 and C3, but one has to test other products. I am doing as you said, Stella about burning it for less on the first test. I usually burn so they are idiot proof right from the beginning. Very ugly melt pool and definately not from soot, must be FO. I use this FO in paraffin pillars and colour and don't have any issues. I am going to test this FO in C3 and let you know (when I get a gap to do some testing) Ta again for your replies