Originally Posted by
unterhausen
It's not likely that you can get rid of it. It's carbon precipitation, and if it's outside the fluxed area there is little you can do other than use less heat. It's happening under the flux too, but the flux carries the carbon away from the joint. Gas fluxer seems to help with this, not that it matters.
Thanks for the info. I assume this is where the fine tuning of heat and time spent in one area comes into play....... I have been playing around with 1/16 LFB and 3/16 LFB. I had been having problems building a bigger fillet with the 1/16 but much more success with the 3/16 however it needs more heat. Practice practice practice =)