Undercoating
Thread Starter
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 314
2024 C3 of the Year Finalist - Unmodified
Undercoating
What works best for removing dealer-installed undercoating from 1969? The heaviest appears to be in the wheel wells. I'm trying to avoid bad fumes in the house as well as blowing myself up and/or burning the house down. I used an aircraft stripper on the spare tire carrier, which worked quite well, but that was outside in a tub. I've been told to use lacquer thinner as a final cleaner/prep on much of the underbody.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
Depending on how thick it is, you might be wise to start by getting most of it off with a putty knife. Lacquer thinner will 'cut' it, but it will take a lot just to get the remaining stuff off after you use the putty knife. Also, you may want to leave some of it at the upper portion of the wheelwells just to prevent any rocks thrown by your tires from hitting there and causing 'star' cracking in your paint [on top of the fenders]. When done with the undercoating, use semi-flat black spray paint to dress up the wheelwell areas. 
Thread Starter
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 314
2024 C3 of the Year Finalist - Unmodified
Racer
Joined: Mar 2004
Posts: 354
Likes: 0
From: Fredericksburg Va
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
I've done this on six cars now and it's my least favorite chore of a restoration. Nasty business.
The undercoating is an oil based product so I've used engine degreaser (the regular liquid, not foaming), called Castite from O'Reilly's (Gunk isn't as effective) which comes in 20 oz. spray cans. Or I've used WD-40, $14 by the gallon at Lowe's plus a $2 sprayer.
The Castite is superior to the WD. You'll need 6-8 cans to complete all four wheel wells and the underbody.
The Castite really softens up the undercoating.
Also, you'll need a 1" metal paint scraper (forget plastic) and 4-6 sheets (10" x 12"?) of the course Scotch-Brite. Cut each sheet into fourths.
Also, purchase 20 or so small terry cloth towels. Lowes used to have the bag of rags for about $15.
And yeah, as recommended above, a couple of dozen vinyl gloves are a good idea.
Pretty straight forward.
Spread a big plastic sheet or a lot of newspapers under your work. Do about a 10" x 10" square at time;
1) spray
2) scrape
3) spray again
4) rub with Scotch-Brite
5) spray again
5) wipe clean with your rag
6) Repeat as necessary
Good luck!
The undercoating is an oil based product so I've used engine degreaser (the regular liquid, not foaming), called Castite from O'Reilly's (Gunk isn't as effective) which comes in 20 oz. spray cans. Or I've used WD-40, $14 by the gallon at Lowe's plus a $2 sprayer.
The Castite is superior to the WD. You'll need 6-8 cans to complete all four wheel wells and the underbody.
The Castite really softens up the undercoating.
Also, you'll need a 1" metal paint scraper (forget plastic) and 4-6 sheets (10" x 12"?) of the course Scotch-Brite. Cut each sheet into fourths.
Also, purchase 20 or so small terry cloth towels. Lowes used to have the bag of rags for about $15.
And yeah, as recommended above, a couple of dozen vinyl gloves are a good idea.
Pretty straight forward.
Spread a big plastic sheet or a lot of newspapers under your work. Do about a 10" x 10" square at time;
1) spray
2) scrape
3) spray again
4) rub with Scotch-Brite
5) spray again
5) wipe clean with your rag
6) Repeat as necessary
Good luck!
Last edited by 73, Dark Blue 454; May 23, 2009 at 12:31 AM.
Thread Starter
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 314
2024 C3 of the Year Finalist - Unmodified
Thanks for the suggestions. Nothing like hearing from those who have been there and done that. I sure am glad I've followed others advice so far, like:
1. Educate yourself and look before you buy. Joined NCRS and searched for 1-1/2 years.
2. Drive the car and enjoy it before spending more money. See if you like the hobby.
3. Restore the mechanicals and underbody first. They are the most important & difficult.
4. Save the paint, chrome, carpet and interior for last.
1. Educate yourself and look before you buy. Joined NCRS and searched for 1-1/2 years.
2. Drive the car and enjoy it before spending more money. See if you like the hobby.
3. Restore the mechanicals and underbody first. They are the most important & difficult.
4. Save the paint, chrome, carpet and interior for last.
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Race Director
Joined: Jan 2007
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From: NYC NY
One additional step that has not been mentioned is it doesn't hurt to have a heat gun. It really helps on the tough spots but be carefull and keep the gun moving because they get VERY hot. Of course you can't use it on top of anything flamable. 
Work in a small area and putty knife will scrape the undercoat off. Afterwards you can go over the area with a solvent.
Work in a small area and putty knife will scrape the undercoat off. Afterwards you can go over the area with a solvent.