Corrosion cleanup yet again

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Rich Feldman
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Corrosion cleanup yet again

Post by Rich Feldman » Mon May 14, 2018 7:44 am

Tyler Meagher's encrusted vacuum pump restoration deserves a round of applause.
Not so my electromagnet "starter plates", which got ugly because of my own negligence during years of storage.
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Paint scraper, Scotchbrite, steel wool, WD-40 (dribbled from an aerosol can that'd lost its pressure), and lots of elbow grease restored the surface to reasonable flatness.
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I think the original rust-resistant plating is tin. Magnetic flux joint surfaces don't benefit from a thin layer of tin, but it's much better than an irregular layer of pittium.

Now a question for the forum.
The cleanup exercise brought to mind the old Navy aphorism: "If it doesn't move, paint it." This weekend I spent more time degreasing steel than removing corrosion products. What are good ways to do that at home?

Recently machined parts were oily, from fluids like Tap Magic. Most of it came off with lacquer thinner, citrus degreaser, acetone, or camp stove gasoline. It's not practical or safe to use those materials in a bath, or a hose-end sprayer. I swabbed around with a small, very "wet" paper napkin or towel, followed immediately by dry napkin to soak up oily solvent. But there seemed to always be some residual oil being pushed around. Happier in contact with steel than with paper? A squirt of aerosol "flux remover" made a puddle that expanded rapidly -- eager to wet the steel -- with its edge pushing a visible ring of oily liquid that had fine particles in it. Still not well picked up with a dry napkin. Do solvents need to drip off from the workpiece to carry away the last oil and grease?

On the smooth tin-plated parts I tried a more aqueous approach, but might have made things worse. Started with creamy lanolin-filled hand cleaner, rubbed around with a plastic dish scrubber and then hosed off with water outdoors. Maybe it was the lanolin that left the surface hydrophobic. Tried to take that off with liquid dishwashing detergent and more hosing with water. Never got to the point where the aerosol flux remover test didn't show differences between places. What next? Soapy steel wool pad? Steam jet?

Hints welcome! Thanks.

p.s. maybe chemistry alone isn't enough. How about scrubbing with a stiff brush. Toothbrush? Wire brush?
There is a vapor degreaser at work, for circuit boards. But it's filled with thousands of dollars worth of Vertrel or Aerotron solvent -- gone are the TCA and TCE days.
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John Futter
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Re: Corrosion cleanup yet again

Post by John Futter » Mon May 14, 2018 6:59 pm

use petrol as a degreaser on a rag (careful not to smoke at the same time)
then Simple Green / CLR to remove the last traces of oilyness

Bruce Meagher
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Re: Corrosion cleanup yet again

Post by Bruce Meagher » Tue May 15, 2018 6:58 am

For greasy parts I’ve found a liberal amount Gunk engine degreaser gel, a little time, some scrubbing, with a good rinse, works well. Then a Simple Green scrub and wash leaves most parts plenty clean for my painting needs. A thorough water rinse is a critical part of this process. As the label says "rinse and repeat!"

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Re: Corrosion cleanup yet again

Post by Rex Allers » Tue May 15, 2018 10:36 am

For heavy grease and crud mixed, Gunk or the like is good. For lesser greasiness Dawn dish soap is great. It's cheaper than Gunk (or equivalent) and I used it for a lot of parts on a metal lathe rebuild. Also not too bad on skin. It seems to be the go-to choice for degreasing birds after an oil spill too.

Not the current subject, but another tip, I've found that for removing stuff like glue from label residue stuck on panels, but not the paint or printed text the glue is on or near -- the cream stuff for cleaning your hands after they get greasy and dirty works good. Not too strong for the paint and because it is creamy you can dab it on and leave it for a while. It doesn't run off.
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Frank Sanns
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Re: Corrosion cleanup yet again

Post by Frank Sanns » Wed May 16, 2018 2:50 pm

When I am going to electroplate something, I use this material from Caswell to be sure every bit of oil is gone. They also have good electroplating solutions. No affiliation.

https://www.caswellplating.com/sp-clean ... easer.html

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Andrew Robinson
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Re: Corrosion cleanup yet again

Post by Andrew Robinson » Thu May 17, 2018 9:48 pm

Some of our military parts get an ultrasonic bath before plating. There are budget bench top ultrasonic cleaners out there that would probably work nice for you at home.
I can wire anything directly into anything! I'm the professor!

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Rich Feldman
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Re: Corrosion cleanup yet again

Post by Rich Feldman » Fri Jun 08, 2018 10:31 pm

Rex, thanks for the hint about oily hand cleaner for removing sticker gum.
It has worked for me.
Today I got a similarly good result using oily sunscreen lotion that was handy.

That was to remove an old SKU sticker from a pipe nipple. My first MKS 901P transducer is now ready to plug in to facility vacuum at my workplace, for voltage logging experiments -- with zero trips to the hardware store. :-)
Not counting the electrical connections. Just bought a DE-15 HD female connector with solder cup terminals, instead of cannibalizing a VGA connector from some monitor or computer.

It looks like if a KF connector had superficial damage or corrosion on the sealing surface,
it could be fixed by lapping with fine sandpapers on a flat surface.
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Rich Feldman
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Re: Corrosion cleanup yet again

Post by Rich Feldman » Tue Jul 10, 2018 12:56 am

Found yet another kind of grease that oily/creamy hand cleaner is good for.
Tacky, semi-dried cooking oil deposits on an exhaust fan grille.
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As Rex said, you can apply a substantial thickness and it'll stay in place for a while.
It did a number on the chrome spray painted surface. Its own residual oilyness was removed with toluol, which also did a number on what was left of the 1950's factory paint job. But enabled the goal of a fresh coat of chrome spray paint.
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