<VV> Undercoat Removal Tips

[Tony Underwood]

At 05:33 AM 10/29/2011, Ulli Dittmar wrote:
>Hi Ray,
>
>I restored many cars and had a lot work with sanding, grinding and 
>manual removing the undercoating.
>The last car I did was dry ice blasted. Fantastic, no undercoating, 
>no grease no oil left - the best is that non of the   original metal 
>will be taken off



Dry ice blasting is efficient and nondestructive.  The aviation 
industry uses it to strip paint from aircraft.  When the prototype 
707 "Dash-80" was pulled out of the desert storage lot and flown back 
to Boeing for restoration, still wearing its faded and dulled demo 
paint, the work began with stripping all the ancient paint off with 
frozen CO2 granules.  It does double duty by abrading the paint and 
chilling it as well, making it brittle and easier to strip without 
damaging the aluminum underneath which according to some of the gurus 
actually hardens when hit by the super-chilled blast media which 
shrinks the metal slightly, causing the paint to pull loose from the 
metal... or something.  Sounds like it makes sense... and it sure 
worked for Boeing since the Dash-80 707 demo liner came out of the 
strip shop looking clean as a chrome purser's whistle.

Good thing, since unlike most airliners, the Dash-80 was "all 
prettied up" when it was rolled out of the factory and had a lot of 
paint on it and required a lot of stripping.   Maroon and 
yellow.   Yeesh.   Oh well...  ;)   It can be seen on display at the 
Smithsonian Udvar-Hazy facility.

Stripping a car with supercooled CO2 blasting would be pretty handy 
but not very practical since it's not likely your typical paint & 
body shop will have the hardware on hand to do it.   Probably the 
next best thing, although a LOT more messy, is soda blasting.



tony..