And to more completely answer your questions.

Stripping with Caustic removes Tin from the surface, thus making the minimum
temperature required for fusing/reflow go higher, and thus fusing may not be
as complete, especially in the center of the hole, which will appear white,
or hazy, instead of being shiney.

Further, the corrosion of the Tin has the potential for leaving oxide
residues, which people will see as "white residues",

Some people used to go so far as to immersion Tin the surface after stripping
to compensate for this sort of problem.

I have written a paper on fusing and reflow problems, and thought that no one
in the world would ever want to read it ever again.  If you want a copy, tell
me if you want me to attach it to an e-mail, or to send it via snail mail.

Rudy Sedlak
RD Chemical Company

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