Recently thanks to some shop space lent by my brother in law I have been consolidating and sorting all the rusty old cans of bolts, screws, plumbing parts, sockets, drill bits, screwdriver bits, small hand tools, and other small steel items that I've collected via my garage and estate sale habit. There's enormous value in just sorting wildly mixed "junk" into collections of like items and storing them in labeled containers, and it's very soothing. However, a lot of items are badly rusted -- if not beyond functionality, at least to the point where they are difficult and annoying to handle and use. I do not simply want to give up on these items, but we are talking thousands and thousands of pieces. It's not practical to hit each one with a wire wheel or a hand-held piece of steel wool. I need something that can do a few pounds of small rusty objects per batch.
So I've been doing my research and there are a bunch of internet-suggested approaches. What follows are my impressions-from-research, could be wildly wrong:
1) Piecemeal hand work with wirebrush and steel wool. Simply not an option for me due to volume.
2) Piecemeal hand work with wire wheel on an electric bench grinder. Better, but again, not an option due to volume.
3) Chemical methods, acid: Commercial acids, vinegar, acidic soda pop, molasses-and-water solution with citric and organic acids, pick your acid. Have not ruled out this approach using weaker food acids but I am not keen. Stronger acids tend to remove too much, pit or weaken the work pieces. Safe handling is an issue, plus disposal of spent solution is potential environmental problem. Weaker acids take a long time and leave behind work pieces that still need substantial hand work.
4) Chemical methods, bases: strong caustic solutions, usually heated. Can be jury-rigged but is typically done in an expensive machine-shop parts washing machine. Hot caustic liquid is nasty stuff, posing safe handling and disposal issues. Less likely than acid methods to damage the workpieces.
5) Chemical methods, commercial preparations: There are a bunch of proprietary goos that are less obnoxious to work with than strong acids or bases. Unknown toxic gick in a can, literally. Supposedly safe to handle and dispose, but that's as judged by non-permie marketeers I don't trust. Supposedly these work pretty well. They're expensive -- another strike against.
4) Bulk dry/air abrasion methods (sandblasting tanks and so forth). Requires expensive equipment, sometimes expensive blasting media, can create respiratory safety issues unless pretty serious safety gear is used. Tends to damage work pieces especially if lots of diverse pieces are being run at once.
5) Bulk wet abrasion methods (like rock tumblers) where hardware is tumbled, with or without an abrasive medium, in a liquid (
water with or without detergents, usually). Requires expensive equipment unless you jury-rig something, reports are mixed about whether and how well it works on small rusty steel parts, reports are mixed on extent to which threaded surfaces are deformed and how tricky it is to tumble long
enough to remove rust without damaging work pieces. Noisy.
6) Bulk vibratory abrasion methods. Similar to above but using a commercial vibratory cleaner vessel that just shakes, without tumbling. Always with a purchased abrasive medium, sometimes with added liquid. Noisy, usually requires an expensive purpose-built power tool, said to deliver pretty good results.
7) Electrolysis. Low voltage direct current (such as from a car battery or battery charger) passed through water with enough washing powder (sodium carbonate) in it to give it lots of ions. Negative electrode (cathode) is an open steel basket with the rusty stuff in it. Positive electrode is a piece of junk steel we do not love and don't mind depositing crud on. In operation, emits small quantities of both hydrogen and oxygen gas, creating potential for "boom!" if not mindful about ventilation -- especially given that we are playing with spark-generating technologies. However, the amounts are very small, thus likewise the risk if operator is at all times mindful. Electrolytic solution to be disposed of is essentially water with particulate iron in it -- much less gicky than most of the chem-based approaches. Internet demonstrations are impressive, and compare favorably to the caustic/acidic approaches.
8) Ultrasonic cleaning. Requires an expensive tool, no jury-rigging. Usually combined with heat and chemicals in the tank of the cleaning device. Said to be wonderful on grease and oil and miscellaneous gunk, but quite ineffective on heavy rust, so worthless for my purposes. Some people have claimed that it's a second-pass tool, for turning stuff that's already "visually clean" into "chemically clean" items suitable for having further finishes applied.
So, what is my question?
I'm not fundamentally asking "what is the most
permie way?" I think we all know it's to keep the rusty stuff in a
bucket and hand-clean individual items at need. Except, I'm trying to generate surplus here; I'm trying to repair/upcycle garbage into ready-to-use collections that other people can grab-and-go with. We are already noticing substantially fewer hardware store runs to buy "new stuff" out of this shop, just from having my sorting boxes and bowls and containers full of useful small items spread out all over about eight linear feet of shop bench under a strong light. (A side
project has been refurbishing a variety of small parts bins and chests-of-drawers so that sorted material can be stored and accessed sanely.)
No, I'm not starting from "the most
sustainable, non-toxic way" question. I want to know which of these methods is actually most practical and effective to use on a workbench scale to clean a few pounds of stuff at a time. I'd really like to hear from anybody who has done this, routinely and happily, to many hundreds or thousands of items. Tell me your methods! What worked, what failed? Help me avoid your mistakes so I can make new ones!
My notion is that once I zero in on a method that works, I can worry about tweaking/managing/improving it from a toxicity and sustainability perspective. I'm pretty sure that the net benefits will always pencil out, given the embodied
energy and natural resource extraction cost of using new instead of refurbished stuff.
That said, I already know that I'm not going to be using any of the methods that rely on strong acids or caustic bases. I simply am not interested in exercising the necessary care to protect myself, the workpieces, my work environment, and the broader environment from those ingredients. Still, if that's what works, I'm interested in hearing your specifics, if only out of intellectual curiosity.
Now it's the time where I shut up and y'all start talking!
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