3M Body Schutz...

You spray it with a special gun that costs about 15$. You can get both at
your local auto paint store. Shutz comes in both paintable and non-paintable
versions.

comes in cases of 6 quart bottles. My "gun" screws onto the top of the
quart can. Hook the air 

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to it (regulator to 50lbs)- and pull the trigger. Be careful to tape/paper off
the edges where you 
don't want it to go.. If you do get "overspray", you can wipe it off with
mineral spirits if you get 
to it fast enough.

Ray
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buy it in a small can with applicator brush, to fill seams. It's says 
"3M Body Shutz and seam sealer" on the can.


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used a couple of 5 gallon pails of spray in truck bed liner on the
undercarriage from the bottom of the firewall back to the rear bumper.
Also sprayed the interior floor from firewall back to package
tray.sealed all seams watertight and quieted it down nicely.
Guys with early streetrods use the stuff on the underside of the fenders
front and rear to reduce stone chips and cracked paint from tires
throwing rocks up into said fenders from underneath.

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