A 50%/50% solution of boric acid and alcohol works well for
firescale prevention. Ignite the alcohol after dipping the piece
and as it burns off it leaves a coating of the boric acid. Flux
your joints and pickle after soldering and your on your way.
A long time ago, I was using boric acid and alcohol for coating
jewelery prior to firing when I noticed a slight burning
sensation in my left hand. Upon looking down, I noticed that the
whole jar was ablaze. In my haste to put it down, I managed to
spill it over most of my hand. I had more than a little trouble
getting it out. Not too big a deal. No real damage to my bench or
any tools. My hand required six or eight months to heal. Since
that time I have forbidden my mechanics from using the mixture.
Instead, we just use the powdered boric acid. Seems that static
and grease can go a long way toward causing the boric acid to
stick to the work. It's quicker, too, as one isn't inclined to
wait for the alcohol to burn off before firing.
@Bruce_Holmgrain snail mail: POB 7072, McLean, VA