Undercoating removal...Success!

[nealtovsen at yahoo.com (Neal Tovsen)]

The dry ice trick does indeed work...on asphalt-based
SOUND DEADENING. I used it on the inside floorpans of
my Mk1 when I was doing repair work.

Undercoating is a bit of a different animal. I'm not
sure it would work at all since it is mostly a
combination of foam rubber and seam sealer on our
cars. But in my case, since I didn't have a
rotisserie, I was unable to even try it (dry ice
doesn't stick to the underside of your car very
well!). 

I just used the torch-and-scraper routine. After you
do it a while, you can usually get a reasonably quick
rate of progress. The trick is to soften it enough to
get the putty knife to slide underneath, but not
enough to "blacken" the undercoating...at which point
it catches fire, makes LOTS of fumes, and is tough to
put out again. If you do it right, it will come almost
shiny-clean. 

Then you just need a flexible sanding disk on a drill
to take off the little bit that is left. Wire wheels
work, but the coarse sandpaper was much better. The
best was a RotoZip with the angle-grinder-like
attachment. They had this funky 3M-green-scrubby-like
abrasive pad/disk that was fantastic. But after
blowing up two RotoZips in two weekends (cheap-a$$
POS!!), and finding out that those pads were
expensive, I went back to the
sandpaper-disk-in-a-drill routine.

But don't kid yourself, it will take a LONG TIME to
get anywhere. I probably spent more than a day on each
inner front fender. I did the inner fenders, one outer
fender (the other was new), the firewall, and just
enough of the floorpan so that I could weld in the new
one. Between that and the sound deadening, that was
more than enough work for me! Anyone who does that to
an entire car chassis has my respect...but in reality
probably deserves to be put away in a padded room. :)

Oh, and I tried a few different chemicals, including a
spray-can product advertised by Eastwood as being
"undercoating remover". It sucked. Took the paint off,
but didn't affect the foam rubber undercoating at all.
Don't waste your money.

Neal

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Message: 35
Date: Wed, 19 Nov 2003 08:08:50 -0500
From: "John C. Worden" 
Subject: Re: Undercoating removal...Success!
To: Ron Pieper ,scirocco-l@scirocco.org

I had pretty good luck with the part of it burning. 
It would burn when
the torch was on it, but when I removed the torch it
would go out shortly.
Maybe it has something to do with the age of the stuff
or something.  I
wouldn't guarantee that someone else's car wouldn't
catch fire.

John