I know I have to use flat beer. Some say to boil it, others just say to open and leave out. Its opened going flat and I may boil it just for extra measure. Anyting else I should know. Does it accelerate trace? Do beer soaps tend to be tan or do they go darker than that. I am using a F.O. that goes tan on its own and I am wondering how dark I can expect. I am not using a real dark beer. Thanks for your help.