The process for removing the factory undercoating has been discussed multiple times in this and the original forums. The basic process is to use heat (torch or heat gun) to soften the undercoating, scrap it off, then remove any remaining undercoating using a solvent (carb cleaner, lacquer thinker and paint remover have all been used). I’ve just finished removing mine and have an addition to the process I think is worth passing on: steel wool.
I used a heat gun for my first pass. I tried a propane torch, but a heat gun seemed to work as well and minimized the risk. I found a relatively small scraper, 1†in my case, worked best. Immediately after scrapping off a small area, I rubbed coarse steel wool over it to remove the remaining traces of the undercoating. In most cases, this took it right down to the primer. When it didn’t, it was usually because the steel wool was clogged and needed to be replaced. Occasionally, a little more heat was needed, but the sheet metal seemed to retain the heat long enough that I could scrape an area, steel wool it, then move to the next fairly efficiently.
There are two advantages to this approach. First, steel wool works very well on irregular areas and curves. In many cases, (areas like welds were particularly difficult to scrape) I skipped the scraper entirely and just used the steel wool. The second is that it minimizes the time needed with the solvent. Generally speaking, a rag soaked in lacquer thinner seemed to do a very good job of quickly removing anything that was left over. The drawback is that the steel wool does scratch the primer up, in many cases down to bare metal. Finer wool would minimize this (I used grade 3) but it takes more effort and has to be changed more often.
All in all, it is a miserable job, especially as I don’t have a rotisserie and am doing the whole thing on my back. If I had it to do over, I would have paid extra to have it blasted off when I did the rest of the car. But that’s another story.
I used a heat gun for my first pass. I tried a propane torch, but a heat gun seemed to work as well and minimized the risk. I found a relatively small scraper, 1†in my case, worked best. Immediately after scrapping off a small area, I rubbed coarse steel wool over it to remove the remaining traces of the undercoating. In most cases, this took it right down to the primer. When it didn’t, it was usually because the steel wool was clogged and needed to be replaced. Occasionally, a little more heat was needed, but the sheet metal seemed to retain the heat long enough that I could scrape an area, steel wool it, then move to the next fairly efficiently.
There are two advantages to this approach. First, steel wool works very well on irregular areas and curves. In many cases, (areas like welds were particularly difficult to scrape) I skipped the scraper entirely and just used the steel wool. The second is that it minimizes the time needed with the solvent. Generally speaking, a rag soaked in lacquer thinner seemed to do a very good job of quickly removing anything that was left over. The drawback is that the steel wool does scratch the primer up, in many cases down to bare metal. Finer wool would minimize this (I used grade 3) but it takes more effort and has to be changed more often.
All in all, it is a miserable job, especially as I don’t have a rotisserie and am doing the whole thing on my back. If I had it to do over, I would have paid extra to have it blasted off when I did the rest of the car. But that’s another story.
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