water rust and foam?

Phil in Mt · Mar 20, 2010

I have been building a jeep from a pile of old parts, The frame I used was boxed from the front to the back (82 cj5) The low parts of the frame were real rusty and I had to cut the bad parts out and weld in new iron. What I am thinking about doing is to filling the box in with the spray foam you use to set doors and windows. I am thinking that the foam will coat the steel and stop dirt and water from filling the box full and starting the rusting all over agin. The test I done on the foam it seems to be closed cell and does not hold water. the only down side is if I would have to weld on the frame after the foam is sprayed in. Anyone have a better plan?...Phil in Mt

macona · Mar 21, 2010

Paint it with a good paint after all the welding is done. Something like a machine type alkyd enamel would probably be good. That stuff is resistant to most chemicals.

Phil in Mt · Mar 21, 2010

There is no real way to clean the inside so paint will stick, and the only way to spray inside the box is thru 3/4 hole that are drilled oddly in the sides of the box. I have used high pressure water to wash the dirt out after I cut out the bad spots.....Phil in Mt

mm58 · Mar 21, 2010

Why can't you spray the foam in after you do the welding. Just use a reeeeealy long straw on the can, or drill a couple of very tiny holes in the frame to allow the straw inside.

8Way · Mar 21, 2010

Spray Waxoyl or similar product. Eastwood sells it as "Heavy Duty Anti Rust". It's an emulsion of waxes in a solvent that dries to form a barrier to moisture.

I've heard u can use paraffin and kerosene warmed to melt and spray that in, but I'd stick with one of the commercial products. They aren't that expensive.

doug6949 · Mar 21, 2010

All of the household foams I've seen are moisture catalyzed urethane. The get away with calling them "green" because it doesn't use VOC's for solvents.

Urethane is a not-so-scary name for polyisocyanurate. The word cyanide is hidden in there somewhere and that is what comes out when you burn it. Welding over a filled area would be a not-so-green problem.

I like the idea of a wax/solvent coating. McMaster used to sell a metal preservative called SP400 in a green spray can. I think it also comes in quarts. Can't remember the manufacturer - maybe CRC. That stuff lasted forever. It also seemed to stay in your lungs forever if you got a whiff while spraying it. Wear a respirator.

Ghost · Mar 21, 2010

Why not just drill drain holes?

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water rust and foam?

Phil in Mt

Cast Iron

macona

Diamond

Phil in Mt

Cast Iron

mm58

Hot Rolled

8Way

Plastic

doug6949

Hot Rolled

Ghost

Cast Iron

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