View Full Version : Silicone causes rust???

July 8th, 2006, 16:23
I have read on this forum that using silicone on metal will eventually cause it to corrode and rust. Is there any truth to this?

Last winter I was out wheeling, and my rear fenders aren't trimmed. So my tire was banging around on the rear quater panels. This broke the seam around the fuel fill door, which allowed water to come in and collect at the bottom of the quater panel behind the tail light assembly.

To seal this up I used a huge amount of silicone. Is this going to cause my quater panel to rust from the inside out? Should I remove the silicone and seal it with something else?

Any tips on removing the silicone? It's a real tight area and a lot of silicone.

July 8th, 2006, 16:37
exacto blade and some mineral spirits or maybe acetone? I have no idea if it will cause metal to rust.

July 8th, 2006, 16:38
Doesn't help with your immediate problem, but for future reference, GE makes a product called Silicone II you can find at Home Depot. It releases ammonia and alcohol, iirc, instead of acetic acid when it cures. Their Silicone I product is the old fashioned acetic acid kind.

I was in the Goof-Off section of the HD, and I remember seeing a product that said it removed silicone, but I don't recall the product (it may even have been Goof-Off), as I was specifically looking for something that *wouldn't* remove silicone.

Whether it's actually worth the effort, I have no idea.

July 8th, 2006, 20:37
Silicone itself doesn't cause rust, but it traps any moisture that gets under it. And rust absorbs moisture like a sponge and perpetuates itself.
If you silicone over one side of rusted sheet metal, or a blind seam, you've made matters worse.

The opposite side will continue corroding far faster than if it stayed open and could dry out completely. If the water can find any way in, that heap of silicone will trap it and make a rust bucket where your lower quarter used to be.

Getting thick silicone out is a pain. I've had good luck using heat, scrapers and pliars to gnaw it away.

July 9th, 2006, 00:11
Coleman fuel or cigarette lighter fluid (both are mostly NAPTHA) have worked wonders for me to dissolve or soften silicone. I find its best to immerse the part in it though.

July 17th, 2006, 12:53
There was no rust when I applied the silicone so hopefully it isnt too bad yet.

Guess I know what I'm doing tomorrow.