I've sweated plenty of copper to copper but never bronze to copper. I'm trying to sweat a bronze shower drop elbo to copper pipe with little luck. I'm using regular lead free plumbing solder and flux. I'm cleaning the fitting and copper well with steel wool. I've tried my propane torch and MAPP gas torch for a bit more heat. Can't seem to get the solder to wick down into the joint and hold. Is there some special flux or solder that I need to use or some other secret?