Well spotted. I believe you can get Tung oil.

I think its a component in a traditional boat caulking, (with IIRC oyster shell lime and coconut fibre. Potential "Bondo" substitute?) and I've been told by some of my adult evening class students they used it during their National Service to treat the brass buckles on parade dress uniforms.

I've just never got around to noting down the Chinese character and locating some, since for most of my purposes sunflower oil is good enough and dries fast enough in the local climate.

For some purposes, notably underbody anti-rust treatment, you perhaps don't want it to set fast, since you want to give it soak-and-creep-time. Castor oil is probably relatively stable but a bit expensive, followed by rape seed/canola, which is available fairly cheaply.

I didn't know soya oil was classed as a drying oil, but when I've used it my impression (no systematic study) was it had a greater tendency to grow mould, a hazard here especially in enclosed spaces, given the high humidity.

Edited by edlithgow on 14/06/2022 at 00:42

IIRC Waxoyl (which I've only used once, and didn't like that much) is/was thinned with white spirit, which probably renders it quite flammable.

In the past, when spraying oils (usually a mixture of new motor oil and sunflower oil) I've used diesel as a thinner, which smells worse and might be a dermatitis risk, but isnt very flammable.

I think the rags thing perhaps relates to a spontaneous combustion risk, rather than VOC content per se. As I understand it, the large surface area of the rag can give rise to very rapid oxidation of the oil (which has a lot of unsaturated bonds, which is what makes it a drying oil)

This rapid large scale oxidation can raise the temperature above the ignition point.

If I was applying Tung oil to a surface I'd probably be too stingy to use a rag. Even with sunflower oil I usually use a plastic bag glove stylee to spread it, and the plastic doesn't absorb much.

With brake pipes we are talking about a tiny amount, rubbed in with a ball of compressed aluminium foil which conforms to the shape of the pipe. The foil ball can get pretty hot but thats probably friction, and maybe surface oxidation of the aluminium.

Then again some people put petrol in their cars. Doesn't bear thinking about.

They make napalm with it, you know.

Fair enough.

I suppose the spontaneous combustion thing is a bit of a gotcha because its a bit counter intuitive, and in fact tends to especially apply to materials that are not normally especially flammable.

Petrol, for example, is horribly flammable stuff (they make napalm with it, you know) but it isn't likely to spontaneously combust.

2 near-death experiences with petrol, though really impossible to say how near

1) Knocked up by nosey neighbor woman saying my 1800 Marina was leaking petrol from its (brimmed last night, naturally) tank down the street gutter under lots of much more expensive cars.

What to do? Believing that siphoning petrol from a full tank was only likely to work in the movies, I elected to remove the tank and decant.

Lying under the car in a pool of petrol, with the tank lowered onto my chest, I was disconnecting the float sender and worrying about sparks (did I disconnect the battery?) when I became conscious of a face down beside the car.

Nosey neighbor woman. "How are you getting on?"

Did I mention she was a chain smoker?

Couldn't speak at first, then I had to be frigidly polite to avoid agitating the stupid cow, and the long piece of glowing ash just above the gutter.

2) Same car. My First Welding, using TA oxyacetylene kit and the TA inspection pit.

LUXURY

Whats that thing inside this box section that I'm welding a new floor on, directly over my head?

Looks like a plastic pipe. I can tell its plastic because its melting a bit in the heat of the oxyacetylene flame.

Looks like a plastic fuel line, because thats what it is.

OOER!