rust repair for a non handy person
September 17, 2016 3:15 PM   Subscribe

I just bought a vintage sewing machine, which has a rust problem on one panel.

The outside actually looks pretty good, but I can see rust under the paint on the inside (photo 1, photo 2, photo 3). I want to preserve the paint on the outside but stop the rust inside from progressing. How would you attack this? My goal isn't necessarily to fix it entirely, just to stop it getting worse and not to ruin it while trying to fix it.
posted by superfish to Home & Garden (5 answers total)
Rust-Oleum Stops Rust Rust Reformer in a spray can.
posted by MonkeyToes at 3:22 PM on September 17, 2016 [1 favorite]

Does the rustoleum work on rust that's below paint? I assume it's intended for surface rust.
posted by Ferreous at 3:39 PM on September 17, 2016

You cant fix the rust if you can't get to it, and it is all over under that bubbled paint. If you get the machine into a dry - meaning controlled humidity - environment, the rust will stop forming to a large degree.
I think I'd try getting it into a controlled environment and keeping an eye on the rust. It looks like the problem may have been humidity condensing on the inside surfaces of the machine. Air conditioning systems are good at removing humidity from the air. Constant temps will prevent condensation from forming on the surfaces.
If it doesn't stop, you will need to take more aggressive action, like stripping and repainting, which isn't the end of the world. (I restore old machine tools as a hobby. Match the color and no one will ever know!)
posted by rudd135 at 4:50 PM on September 17, 2016 [2 favorites]

Short summary: that piece doesn't actually look too bad if it's going to live indoors in stable air conditioning. It won't live 100 years without paint flaking but, depending on the environment, might outlive your use with only slight visible rusting.

Given that you said you were non-handy, I'd probably just gently brush off what rust is loose then spray the rusty spots with CorrosionX (my personal favorite), Boeshield T-9 (works well and easier to find), or some other greasy/oily spray designed to slow / stop rust. I'd wipe the excess spray off with a rag, promise myself to respray it in a couplefew years, and enjoy the sewing machine. :)

Longer version because I'd already typed it up before I changed my mind:
1. Rust begets rust. Iron (III) oxide takes up more space than the amount of iron that goes into making it, so it forms, disrupts the crystal surface, and thus exposes more fresh iron to repeat the process.
2. Rusting just needs oxygen -- the presence of water / humidity just makes it go MUCH faster.
3. So unless you get rid of all the rust, it'll keep rusting. You have to pick between getting rid of it all or trying to slow it down as much as the piece allows. Getting rid of it all in your case would involve removing a lot of paint, so that's probably right out.

Things you can do to slow down rust:
1. Keep it dry. (Air conditioning, keeping it out of temperature cycles which could cause condensation, etc.).
2. Remove / convert what rust you can. There are books of things you can do. At the brute force end I tend to rely on wire brushes and naval jelly. At the more delicate end I'm a big fan of a wire brush and a bath in Evap-O-Rust (but you have to submerse the entire object, which means temporarily removing the other bits and a risk of altering the paint color). That will convert the rust into something stable and less hygroscopic.
3. Slow down the oxygen getting to the surface. This is tricky to balance with NOT trapping water, but there's a reason that people oil old rusty tools: better oil taking up space than water and oxygen. If you're good with a wire brush (prep, removing most of the rust) and paint brush, POR-15 ("Paint Over Rust") works extremely well but you'd be effectively painting those spots.

For something that looked that nice, I'd likely start with a little gentle wire brushing on an inconspicuous *inside* spot and apply naval jelly with a small art brush. Apply, rest, wash off, examine. If I liked what I saw (didn't attack the paint too quickly, etc.), I'd treat the worst spots and the few big chips on the exposed faces. I'd repeat applications until I saw metal instead of rust. Then I'd coat the exposed iron bits with a (clear, oily/waxy) surface protector like CorrosionX, T-9, etc. Or maybe even a little art brush with a dab of enamel paint.
posted by introp at 5:56 PM on September 17, 2016 [1 favorite]

If you aren't great with paint, and confident about disassembly and willing to put a lot of time into this, this is a time to leave it (mostly) alone.

Because that isn't really paint, it is enamel. I can't tell what machine it is from your limited photos, but it looks like something from the 60s or later. If you can find a replacement from a donor machine, that is the best option.

If it were one of mine, and I couldn't get a part but was worried about rust, I'd use something clear and removable to cover the vulnerable spots. Like clear nail polish. Or if there are places that might snag thread, a bit of sand/file with emery cloth or cord and clear nail polish over the spot. Touch up as needed. That is really what I would do, and have done.

Unless you know what you're doing, or are willing to accept an unusable result and total loss of value/investment, go small and reversable. Tape comes off, nail polish comes off.
posted by monopas at 7:33 PM on September 17, 2016

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