Thanks Gary,
Here's the real life problem...
After cleaning the Al with a clean wire brush, I apply the flux. I heat
the joint and LONG before the joint has reached the melting temp. of the
solid solder, the flux begins to smoke and turn black forming a nice
hard barrier between the workpiece and the applied solder. As things
currently stand, it seems that I can't help but scorch the flux, to my
chagrin. When all is said and done, I'm left with 2 separate pieces of
nicely scorched Al. BTW, the solder and flux were purchased as a kit.

Rich