Blackened Skylight

August 20, 2005 1:01 PM

How do I get dried roofing tar off a polycarbonate skylight?

I hate the thought of having to buy a new skylight but so far I have not found anything to get this tar off of it.

posted by Danf to Home & Garden (12 answers total)

Gasoline. No, seriously, I tarred a roof once, and the best way to get it off my skin was some gasoline. It dissolves it very quickly (with a little rubbing). Just try not to light yourself/your house on fire.
posted by Mach5 at 1:09 PM on August 20, 2005

Warning: I'm not sure if gasoline and polycarbonate get along.
posted by Mach5 at 1:11 PM on August 20, 2005

Response by poster: True. . .I tried mineral spirits but it did not even touch the dried roofing tar. . .and I would like something that the plastic will hold up to.
posted by Danf at 1:13 PM on August 20, 2005

Well, if mineral spirits or kerosene don't work, you could try Acrysol.
posted by Civil_Disobedient at 3:53 PM on August 20, 2005

What about that tar remover they make for autos? Did you try that stuff?
posted by lobstah at 4:06 PM on August 20, 2005

Before googling, I would have said go for using the gas... but it looks like Polycarbonate has poor resistance to hydrocarbons, which the bulk of gas kerosene.
It stands up to non-oxidizing acids and weak alkalis apparently.

So maybe Boric Acid? One of the more available medium strength organic acids I could find.

This page lists freezing/peeling, and using WD-40 (because of the solvents I suppose).
posted by Jack Karaoke at 4:14 PM on August 20, 2005

WD-40 removes road tar. Might work on roofing tar too.
posted by buzzman at 5:39 PM on August 20, 2005

WD-40 might work. Hell, WD-40 is like the duct tape of the chemical/lubricant world.

Also, head down to the local auto parts store and, in the section with car washes and waxes, you should find some Bug and Tar remover. This might be a little more gentle since it is meant for car finishes.
posted by Thorzdad at 8:16 PM on August 20, 2005

If gasoline doesn't work, it's highly unlikely that WD-40 will work. It was designed to dispel water; the penetrating qualities were a much-marketed side-effect, and not nearly as effective as, say, Kroil, which is designed for that sort of thing.
posted by Civil_Disobedient at 9:21 PM on August 20, 2005

When I get roofing tar on my hands, it comes off easily with that orange scrubby stuff with orange oil and pumice (I think GOOP is a brand). You know, the stuff sold for mechanics and the like.

Now, you probably don't want to use this 'cause it'll scratch up the skylight, but you can pick up some straight orange oil-type degreaser. There's also the possibility of the Castrol "purple stuff" degreaser or generic equivalent (they always seem to be purple).

Obviously, test first. You may want to mechanically remove as much as possible before breaking out the chemicals.
posted by RikiTikiTavi at 10:35 PM on August 20, 2005

Ether and carbon tetrachloride both dissolve tar. Ether is available only by prescription, and carbon tet is banned, though.
posted by KRS at 12:24 PM on August 22, 2005

heat gun & putty knife? that's how i got black floor-tile tar off my wood floor...just be careful not to melt the plastic skylight.
posted by jacobsee at 1:48 PM on August 22, 2005