FWIW, companies that blast cars don't use sand anymore at least the better
ones don't. As a matter of fact with all the pamphlets I receive at various
car shows and swap meets there isn't one company that uses sand. Some use
proprietary blast media and others use plastic media and others use oxide.
Granted, plastic media doesn't remove rust but neither does it warp panels
or fold the edges to hide or encapsulate rust pockets.
The body shop still sands the car down and takes care of heavier rust by
other means; my shop used chemicals and then washed it off.
Media blasting is still the most preferable and cheapest way to remove paint
IMHO. Compared to what a shop would charge to remove paint by sanding and
grinding it's cheap.
While it may be nice to dip a car, that's not an alternative when there are
no shops in your area. The thought of towing a car a few hundred miles and
then returning to pick it up a week or several days later is not a viable
alternative IMHO. In my case the arguement of which process to use is moot
for the above reason and for many other people too.
Mike
----- Original Message -----
From: "snyler" <marc@animalfirm.com>
To: "Andy Cost" <andycost@att.net>; " roadster List"
<datsun-roadsters@autox.team.net>
Sent: Thursday, December 20, 2001 10:58 AM
Subject: Re: Undercoatings
> Andy Cost wrote
>
> >Media, sand, bicarbonate blasting seems like a good idea but it has
> >drawbacks too. It is very easy to warp the panels with blasting. It
> >doesn't remove rust. Rust forms pits in the steel. When you blast the
> >steel it removes a lot of the rust, but it also folds the edges of the
pits
> >over. What you end up with is a very smooth looking rust free part.
When
> >you put it under the microscope there is still rust living down in the
pores
> >and covered over pits. The only way to get it out completely is
immersion.
> >My bet is that the parts that you had blasted will form rust bubbles
under
> >the paint within ten years.
>
>
> There is truth to this, but I think the peening-over-rust dangers of
> sandblasting are overstated. Of course a dipping place will tell you
> blasting will ruin your car, and a blasting place will tell you dipping
> will ruin your car. The truth is probably somewhere in-between. A well
> sandblasted part which is well prepped and painted will probably last
> well. Rust needs oxygen, so even if there is some rust you can
> significantly slow it with good prep and paint. Significantly slow it to
> the point of nothaving to worry about it. There's still te warping
> danger of blasting but doen't this apply mainly to flat panels?
> I do have some rust on my car, but it looks like Bondo and dirt
> between panels where paint and sealer didn't get are the culprits. Paint
> was removed abrasively in that case.
>
> -Marc T.
>
> ==========================================================================
> Marc Tyler TDROC Sisterdale TX
> 1970 1600 #SPL311-31016
> 1965 L-320 #L320 013642
> http://datsun_marc.tripod.com/cgi-bin/datsun_homepage.html
>
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