Posted by chris case on Thursday, May 04, 2006 at 1:19PM :
In Reply to: I agree posted by David Sherman on Thursday, May 04, 2006 at 12:19PM :
Not enough to set the zinc on fire, just a skosh of a feather. It burns off any oils, and prevents the instability of acetylene from shifting to carbonizing. Surfaces covered with graphite prevent flowing. Try it that way next time.
One old timer told me he would only braze cast if the surface had been prepped by chipping, not grinding, since grinding smears a coat of carbon onto the surface...
I use a can of flux, I hate paying $10/# for the coated rods instead of $3 for a lifetime supply in a can. Plus, I find the coating excessive. Burn off the carbon, and the flux will flow a looong way before dipping in again. I haven't left a copper colored braze since high school, 40 years ago.
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