While I'm asking questions of the list I was going to do a poll on
sandblasting and rust. I've read in a few places that when sandblasting you
should prime the bare surface with a self-etching primer within 1-4 hours to
prevent re-rusting. I've seen this in more than one place and it sounds like
a good idea but in practice I don't see many professional blasters adhering
to that rule and in several car restoration programs I see bare metal bodies
sitting around for days or weeks inside dry shops. In my own experience I
have a panel that was sandblasted and left bare and spent two years in a
metal storage building with no climate control and it emerged with no
idications of any rust at all.
Why do I ask? Why not just be safe and paint right away? Here's why: I'm
blasting an entire body to get ready for paint. I've got a pressurized
sandblaster and it works great but with the seam sealer and undercoating
(what's left after torch and a putty knife) slow the process down
considerably. I cannot even complete the project in under four hours much
less complete it and paint it in that time. It's possible to do it a section
at a time but the section that gets painted is going to get very, very dusty
and I can't go back to laquer thinner to clean it up without messing up the
paint and I don't dare use soap and water until the car is completely
covered in a primer and a sealer. It would be very convenient do it a little
a time and keep it out of the elements so that's why I'm asking. I don't
want this to come back to haunt me if I don't heed the warning to prime in
four hours.
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