Turpentine

Spiderman of Calgary · 04-14-2011, 09:24 PM

I did a global search on iRV2 and only came up with 4 mentions of "turpentine." And, only one in specific reference to cleaning off old caulking (see 5Th Wheel compartments doors.......). Thus, I'm starting a thread specifically targeting the use of turpentine in this purpose.

Major problems I've had with dealing with the old caulking, and the big reason I've been very reluctant to fiddle with it, have been

The difficulty of removing it, cleaning the site effectively, and applying new caulking with any reasonable expectation of getting an absolutely watertight seal.

The amount of hard work required to do a good job.

And the fact that I don't "do heights" very well.

Okay, I'll be honest: Not only am I lazy, but I'm also clumsy (majored in college!), and lastly, scared of heights! Three strikes and I'm out, no?

Several months ago, while wintering in the Houston, TX area, I had reason to repair some caulking that was sealing the front end cap of our Dolphin to the roof. Since the caulking was some 8 or 9 years old I had to use a razor blade to scrape it off (brutal and personally dangerous, but it works if you're careful), and then experimented with turpentine and denatured alcohol for cleanup.

BEFORE GOING ANY FURTHER, I NEED TO EMPHASIZE THAT THIS IS A FIBERGLAS END CAP AND A FIBERGLAS ROOF, NOT AN EPDM MEMBRANE!

In removing the old caulking I found that a distressing amount of caulking applied at the factory simply didn't make contact with the Fiberglas as evidenced by the obvious gap between the two and the amount of dirt accumulation in the gap. So, apparently a major problem is getting the caulk to actually make some sort of lasting seal or bond with the Fiberglas. And of course, this is all doubly hard with ancient caulk being nearly impossible to remove 100%, and ancient dirt and grime adhering to the Fiberglas and preventing contact, much less a seal.

I found that the turpentine was very efficient at dissolving and washing away the last traces of old caulking as well as the dirt, but like one of the posters in the thread referenced above, I was concerned about the oily residue it left. So, I washed the residue off with 95% denatured alcohol before I applied the new caulking. After about four months the seal is apparently still holding.

But that leads me to a bunch of other questions:

Because the turpentine seems to wet the Fiberglas quite well, and since it wets the caulking well enough to actually dissolve it, is the oily residue actually bad? Could I have left it on the Fiberglas to help wet it and allow the caulking to make an even better seal?
Has anyone else noticed the same thing I did, namely that factory installed caulking often didn't really bond or seal?
Has anyone else had real, hands-on experience with the use of turpentine in cleaning off old caulking and applying new?
What other solvents might also work? (For instance, one responder in the referenced thread suggested acetone, but acetone will soften or even dissolve the Fiberglas resin, thus raising the potential of serious damage.)
What were your experiences and results? How can we make this chore a little less a pain in the #@$$#?

stuplich · 04-15-2011, 08:55 AM

Many years ago, when I was recaulking an old Minee-Winne, class C, a store that sold automotive finishes recomended a 3M solvent that worked quite well.
I don't recall the name but it was formulated to remove silicone.
It was recommended it because most caulk and many wash products and wax/polishes contained silicone and nothing sticks well to silicone.
The primary use was to clean a sanded surfaces before applying primer and/or other paint.
Mel

Dirtbuster · 04-15-2011, 08:59 AM

You might want to try some paint thinner, or some prepsolve. Go buy your local auto paint store. I am sure that they could give you the right product.