Undercoating removal

[Dick G.]

Does anyone have the magic bullet for the removal of undercoating. Mine is not bad but, I want it all gone. Here are my ideas. Scrape off what I can. Try using wax and grease remover or lacquer thinner or paint stripper. Of course, these can all be detrimental to any future paint jobs, so I will be careful using them. Which of these last 3 will work the best?? Any thoughts or ideas appreciated! Thanks

[Gary S.]

Re: Undercoating removal

I once asked a famous restorer how they did it. His answer was that he used a heat gun, plastic body putty scraper and after the heavy stuff was gone do a final wash with lacquer thinner. I have not tried it. If it works, it sounds like it would not hurt the fiberglass if you were careful with the heat gun. Gary

[Eugene B.]

Re: Undercoating removal

Dick,
When I hear of someone using something as combustible and flammable as lacquer thinner the first thing that comes to my mind is SAFETY.

Prolonged inhalation of this stuff if probably not all that good for your lungs either (although if you blow yourself to kingdom come), I guess any long term effect on the lungs isn't an issue!

If it is the best solvent for the job, please use it with caution and plenty of ventalation.

Regards,
Gene

[Kent K.]

Re: Undercoating removal

Dick,
The heat gun and plastic scraper technique is best to remove most of the heavy undercoating. Try biodegradeable "Simple Green" in a pressure sprayer to remove the remaining & do a final clean-up by rubbing the infected area with a laquer thinner soaked cloth. Use caution and stay safe.
Kent #6201

[Chuck S.]

Re: Undercoating removal

Dick, I would skip the lacquer thinner and paint remover. As mentioned above, lacquer thinner, as well as paint remover, is bad stuff. When removing undercoating from the underbody, you literally end up taking a bath in the remover of choice.

I used plain old paint thinner (mineral spirits), and it worked very well. Undercoating is a petroleum based product that is very soluble in mineral spirits, but you have to keep the solvent in contact with the undercoating until it has a chance to soak in. A disadvantage of lacquer thinner is that you have to apply it in copious volumes to keep it from evaporating before it has a chance to work. At $7-$10 a gallon, that will cost you more than mineral spirits.

A little patience is helpful, too; keep wetting the undercoating with mineral spirits using a throwaway paint brush. As the undercoating begins to soften on the topmost layer, use a plastic scraper (or metal if you're careful) to peel it away, and then rewet the area until you are down to the bare fiberglass. Mineral spirits will not attack your fiberglass, but lacquer thinner will if contacting the fiberglass long enough (not as bad as acetone, but nearly).

Once the undercoating is completely gone, I would do a final wipe down of the bare fiberglass with lacquer thinner to remove the mineral spirits residue.

[Bob D.]

Re: Undercoating removal

Dick, I'm in the process of removing undercoating right now--well when I get of the computer. I'm using a heat gun and scraper to get most of it off and then using this stuff from Eastwood called Undergone. It works well once most of the heavy stuff is off. Undergone is water soluble so you don't have the lacquer thinner problems. The final wipe down though I do using the lacquer thinner. Patience is the best tool of all though.

[Dick G.]

Re: Undercoating removal

Thanks for the tips. My undercoating is cured hard. The majority thus far is flying off. To get a totally clean surface will be the hard part. Thanks

[Jace H.]

Brake Parts Cleaner

I spent a few weeks last winter rwmoving undercoating from my 67. I tried everything and had the best results using "Brake Parts cleaner" in the spray can with a good heavy duty putty knife. I had the car up on a lift and the garage was well ventilated. I would spray, walk away for a minute or two then go back and scrape. I had alot of undercoating and until I stumbled onto the Brake Parts cleaner I was hating life!

Happy Scraping
Jace Holt