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alanganes
03-16-2017, 08:16 PM
Many here are old enough to remember seeing these placed around road construction areas:https://uploads.tapatalk-cdn.com/20170317/854f074714a60bc76d525ea44e3721fc.jpg

https://uploads.tapatalk-cdn.com/20170317/e57322591a242a3702b249f570f4da23.jpg

After thinking on and off for years that it would be fun to have one of these as a sort of industrial tiki torch, I stumbled on one for free the other day. It had been sitting outdoors for who knows how long and is in need of some work.

There is one small rust hole in the bottom that I think I can fix, but the things feels to be full of dirt, likely from years of rotting vegetation, bugs, critters or whatever collecting in there. So I want to remove the top which screws off from what I have read. Of course it is rusted tight. Would phosphoric acid metal prep type stuff dissolve the rust if I kept a dit of it pooled on top so that it could soak down in?

My other thought was to use vinegar, which I have used for other smaller rusted parts. It worked pretty impressively in the few times I trued, though took a long time. Any suggestions?

J Tiers
03-16-2017, 08:21 PM
Water solutions do not penetrate well into oily spaces.

If it is that oily, is it really that rusted? probably could be due to heat. But I'd suppose that penetrating oil might get in through the carbonized old stuff better than water solutions.

alanganes
03-16-2017, 08:28 PM
Water solutions do not penetrate well into oily spaces.

If it is that oily, is it really that rusted? probably could be due to heat. But I'd suppose that penetrating oil might get in through the carbonized old stuff better than water solutions.

That only looks oily. It was still partly wet when I took that picture from me washing the dried dirt and crud off of it. This was sitting either outside or in a old leaky garden shed for ages, and a cursory attempt at gently persuading the top loose (rod trough the top holes and tapping with a small mallet) convinced me that it is stuck pretty tight.

Paul Alciatore
03-16-2017, 08:30 PM
Yes, I am old enough to remember seeing them, just barely. I think they went out before I reached double digits.

As for freeing the threads, I would first try Kroil. I think it would penetrate the threads a lot faster than any water based fluid of gel. It may take several applications and a week or more of soaking in. Follow it up with a light oil.

alanganes
03-16-2017, 09:03 PM
Yeah, Kroil and the legendary ATF/acetone mix are on the list of potential candidates as well. Just undecided where I want to start so thought I'd tap into the collective mind that is the HSM forum...

:)

Mark Rand
03-16-2017, 09:05 PM
Phosphoric acid will remove iron when it's exposed. I would recommend EDTA/Molasses/Evaporust if you can put up with a few weeks to get a result. Electrolytic cleaning will also protect what's left of the original metal and could be quicker. Once you've got down to bare metal on the outside surfaces, you can think about ultrasonic cleaning and heat to loosen the threads, if needed.

Lee Cordochorea
03-16-2017, 09:10 PM
Phosphoric acid does not dissolve rust, but rather converts iron oxide to iron phosphate. I second the suggestions for penatrol type stuff.

lakeside53
03-16-2017, 09:46 PM
Part of the problem is that the rust has expanded in the threads locking the part together. In my experience Evaporust will remove that rust and free the threads. Thoroughly degrease first with a purple cleaner product (many)... which means don't try ER after penetrating oil.. do it first. Keep your casting/ER at 90-100F (light bulb underneath). it will work wonders in a few hours to days depending on the extent of the problem. ER has decent surfactants and has no problem penetrating small crevices - but it has to "eat the rust" as it goes so with a filled void it can take longer. Directed flow from a small aquarium pump can make a big difference.

Remember that any rust eater will also eat the rust off the exterior - do you want to maintain the patina or not?

J Tiers
03-16-2017, 10:12 PM
Phosphoric acid will remove iron when it's exposed. I would recommend EDTA/Molasses/Evaporust if you can put up with a few weeks to get a result. Electrolytic cleaning will also protect what's left of the original metal and could be quicker. Once you've got down to bare metal on the outside surfaces, you can think about ultrasonic cleaning and heat to loosen the threads, if needed.

Phosphoric does NOT eat the exposed iron. That's why it works so well. If you leave something in a long time, the surface will get a coating of iron phosphate, but that is different from eating the iron.

Time? I have never had phosphoric take longer than 45 minutes. Usually 15 to 30 min. The surface will not be affected in that time.

Electrolytic takes a LONG time if you keep the current density down, which I understand is necessary to avoid the hard shell of black stuff on the outside.

I have never tried adding some dish soap to phosphoric as a surfactant. Might work to penetrate, then, if the thing is not actually oily.

alanganes
03-16-2017, 10:17 PM
Thanks for the ideas. I am not overly concerned about the patina on the outside as I will likely end up painting this black, as all those I recall being used when I was a kid were painted black. I have at least one small hole to weld shut as well, once I get this open and emptied out.

I do have some evaporust already. Seems like that may be as good a place to start as any. I suppose I could turn this upside down in a plastic bag so that I can submerge the top in the stuff. I think I will set that up tomorrow. Appreciate the input, will report back as this develops!

lakeside53
03-16-2017, 10:32 PM
Electrolysis doesn't take long (few hours to overnight) at reasonable current densities that do not form magnetite (the rare hard black stuff). I could de-rust that entire exterior overnight (or an 8 hour day if you are so inclined) at 20ma/sq inch then just wipe and hose it all off any sludge. That's plenty "high"; museum quality restorations are often 1-2ma, down to as low as 50 microamps. The important part is to control the current; not just hook up any source and let it rip.

The problem here is that electrolysis cannot "throw a field" around corners or into grooves. i.e. bad choice for de-rusting occluded threads. You could leave it on for a month and it won't chase rust down a threaded connection.

Mark Rand
03-16-2017, 10:33 PM
Phosphoric does NOT eat the exposed iron. That's why it works so well.

Yes it does. Try putting some feeler gauges in it for a few hours. :mad:

J Tiers
03-16-2017, 11:10 PM
Yes it does. Try putting some feeler gauges in it for a few hours. :mad:

Not quite....

What you have there is a DIFFERENT phenomenon.

And, of course, "a few hours" is way too long, all the derusting is finished within one hour or less.

But, when you put certain kinds of hardened material, or springs, into phosphoric, OR Evapo-Rust, or, likely, electrolysis, what you have is NOT attack of the phosphoric directly. It is a type of stress corrosion, and can happen with many different electrolytes.

The deal is that stressed parts can have any small surface defect cause a local concentration of stress. The highly stressed areas are more susceptible to attack by nearly anything. Corrosion occurs there, and proceeds as long as there is local stress.

I had forgotten some rusty gage blanks, for round gages, that were case hardened but not ground to size. Left them in for several hours. The surface was eaten in patterns similar to the patterns of "color case hardening". I have had stressed springs eaten also.

But, I have left ordinary rusty steel in a similar amount of time, and all that happened was a goodly buildup of gray iron phosphate. It is specific to stressed metal, typically hardened, and is not something that happens with ordinary unstressed steel.

And, it never happens in the time that de-rusting actually takes, which is under 1 hour in every case I have dealt with.

Baz
03-17-2017, 01:23 PM
So what were these things? Glad to know I'm not old enough to remember something for a change or perhaps on the wrong continent.

Juiceclone
03-17-2017, 01:47 PM
all those de-rusting mixes work well in their correct situation. The problem here is they will only reach a surface, so a lot of time might be needed for the cleaned surfaces to expose the still rusted areas further down inside the threads. I'd help it along with alternate heating up and then using the chemicals to cool it down, drawing them in.

J Tiers
03-17-2017, 01:57 PM
So what were these things? Glad to know I'm not old enough to remember something for a change or perhaps on the wrong continent.

They are road marker torches.

Used when construction, or maintenance etc was being done. They were set out on the road to indicate blocked-off areas the way lights are used now. If work was being done along the road, the right lane might have a diagonal line of these set out, with flags for daytime, to indicate that drivers needed to move over to the left lane.

Used as one might use flares, only longer lasting.

They usually burned some complete slop for fuel, with a wick at the top. Always were smoky, red-orange flames when I saw them, although they are nominally for kerosene. I'd guess I have not seen one since the 1960's or maybe 1970's.

https://www.youtube.com/watch?v=_0Tc0wym8oA

https://www.youtube.com/watch?v=R5AK0fbq44g

6PTsocket
03-18-2017, 07:55 PM
Phosphoric acid will remove iron when it's exposed. I would recommend EDTA/Molasses/Evaporust if you can put up with a few weeks to get a result. Electrolytic cleaning will also protect what's left of the original metal and could be quicker. Once you've got down to bare metal on the outside surfaces, you can think about ultrasonic cleaning and heat to loosen the threads, if needed.
BIg fan of Evaporust. Have something soaking right now.

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