Bulk cleaning and especially rust removal from bolts, screws, and other small hardware

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!

There are a bunch of videos out there explaining how to do the electrolysis rust removal thing but most of them involve one piece of rusty metal at a time, directly hooked to the cathodic juice.  This one demonstrates using a conductive mesh basket as the cathode, so that you can just put a batch of rusty things in the basket, connect the basket to the juice, and go:




This video is more typical of the genre; it may explain things a bit better, but it involves de-rusting one item at a time:

I'm also digging out a shop corner filled with boxes of miscellaneous fasteners.

For me, anything that takes too much refurb time goes in the scrap metal. But, if I was going to clean rust off bulk nuts and bolts, the only way to go is #6; dry media tumbling. Dump them in, come back later, dump through sieve, blow off with compressed air, coat with light oil, done.

But I have to keep asking myself, "when would I choose this used fastener over a new one?"
And as one predisposed to hoarding, I have to keep reminding myself that the empty space is more valuable than this stuff.

I grew up believing that cocacola would clean the rust off of plowshares...I don't ever remember seeing it in action and have wondered more recently if it was just a 'lie' planted by my dad to keep me from drinking soda? ...and it worked as I've always associated that drink with rust removal.

Could be the ingredients have changed from sixty! years ago? and what might have worked then won't anymore.

Well, here it is...look for something and of course google will find *something*
How to Remove Rust with Coca-Cola

The same carbonated cola drink that refreshes you can be put to work to remove rust. Phosphoric acid in most soft drinks interacts with iron oxide to dissolve rust. Phosphoric acid is also found in commercial cleaners, but of course, the amount in cola is less, so people can drink it safely. While using cola for rust removal is a green cleaning solution, its relatively low level of phosphoric acid means it works more slowly than commercial rust removers.

There you have it
Now, I want to know if it really works...and I don't want to get caught buying a bottle of coke after all these years.

Electrolysis is your best option out of all of them for bulk cleaning. That really works well...

You could also try putting the rusted parts in a solution of acetone and transmission fluid. I have always used this to break bolts free...a homemade WD-40 but works a lot better. Let it soak for a day or two, and then just wipe the parts free of rust when you pull them out of the jug you are using, and then place them into the proper sorted bin.

Incidentally I think you are doing the right thing. For years I thought my grandparents were silly for sorting this kind of stuff and keeping it, I mean the store is just down the road right? But as I have gotten older I have found myself doing the same thing. It is amazing how often I grab the stuff that my Grandparents separated and kept. A roofing repair job just needs a few roofing shingle nails. Sometimes I need five screws 3/4 of an inch long and no longer. And my bathroom door is a barn style door that slides effortlessly on a barn door track that we had on our old tractor shed...from the 1940's! All that stuff has costs to replace new, especially when you calculate the time and money just to get to the store.

The key is to organize it, so you can find it, but if you do, it is really convenient, and saves you a lot of money.

As for the Acetone and Transmission Oil trick...I was proven right. Popular mechanics did a test on all kinds of WD-40 type lubricants and found that on a rusted bolts, of the same size, situation etc; the bolt sprayed with WD-40 took 130 pounds of torque to break free (the worst tested), but the Acetone/ATF homemade lubrication, took just 40 pounds of torque to break (the best tested). It is not very often that homemade is better, but it is in this case.

BTW: I love WD-40, but I tend to use it as a cleaner. Nothing takes grease off clothes like WD-40!

Judith Browning wrote:I grew up believing that cocacola would clean the rust off of plowshares...I don't ever remember seeing it in action and have wondered more recently if it was just a 'lie' planted by my dad to keep me from drinking soda? ...and it worked as I've always associated that drink with rust removal.

Could be the ingredients have changed from sixty! years ago? and what might have worked then won't anymore.

Well, here it is...look for something and of course google will find *something*
How to Remove Rust with Coca-Cola

The same carbonated cola drink that refreshes you can be put to work to remove rust. Phosphoric acid in most soft drinks interacts with iron oxide to dissolve rust. Phosphoric acid is also found in commercial cleaners, but of course, the amount in cola is less, so people can drink it safely. While using cola for rust removal is a green cleaning solution, its relatively low level of phosphoric acid means it works more slowly than commercial rust removers.

There you have it
Now, I want to know if it really works...and I don't want to get caught buying a bottle of coke after all these years.

Yes, it still works. Coke (And other sodas) have carbonic acid (to make the bubbles) and/or phosphoric acid (to add a tangy/sour taste to it.) Coke has both, so it's more effective than some of the other sodas. So soda fits Dan's category of  #3 Chemical methods, it would be classed as a food grade acid.

And your dad was wise to scare you off drinking the stuff, nothing like using facts to make people think!

And your dad was wise to scare you off drinking the stuff, nothing like using facts to make people think!

....soooooo do you think the 'floor sweepings in candy bars' one is true also?  

Judith Browning wrote:

And your dad was wise to scare you off drinking the stuff, nothing like using facts to make people think!

....soooooo do you think the 'floor sweepings in candy bars' one is true also?  

I'm derailing this thread, but yes, there are a certain number of "contaminants" allowed in foods, and if you want to be horrified, look it up...
Back to cleaning bolts

I have done the acid bit, and added shaking them in a big jar with said acid, and had fair results, about 90%, I declared most of the 10% left as not worth salvaging, which gave me pretty high good results numbers. I used CLR, which is a commercial acid that is not horrifyingly strong, but still MUST be treated with respect. I have tried vinegar, and the commercial stuff is not high enough acid for me, if I need to do this again, I'll make a batch of strongly acid vinegar, and use it instead of commercial vinegar or CLR.

Pearl Sutton wrote:

Judith Browning wrote:I grew up believing that cocacola would clean the rust off of plowshares...I don't ever remember seeing it in action and have wondered more recently if it was just a 'lie' planted by my dad to keep me from drinking soda? ...and it worked as I've always associated that drink with rust removal.

Yes, it still works. Coke (And other sodas) have carbonic acid (to make the bubbles) and/or phosphoric acid (to add a tangy/sour taste to it.) Coke has both, so it's more effective than some of the other sodas. So soda fits Dan's category of  #3 Chemical methods, it would be classed as a food grade acid.

My grandfather was a body-and-fender man and ran an automotive paint store.  So I grew up hearing about how much trouble I was gonna be in, if I ever spilled Coke (or any brown soda, not that we ever had enough to spill) on one of our vehicles.  Because it would mar, if not outright strip, the paint, due to the phosphoric acid content.  Warning always delivered with a parental remark about how it probably didn't do any wonders for your teeth or your guts, either.

so i ran into this while looking for methods to remove the husks from walnuts.
I have not done this so, i am adding it as an option for you. I believe it would go in option 3

If you scroll down to the bottom of this link it shows him removing rust from a chain using walnut husk juice. Maybe the juice is less toxic than some other methods

Removing Rust Using Walnut Husk Juice and Cement Mixer


Hopefully this is helpful.

Travis Johnson wrote:Electrolysis is your best option out of all of them for bulk cleaning. That really works well...

You could also try putting the rusted parts in a solution of acetone and transmission fluid. I have always used this to break bolts free...a homemade WD-40 but works a lot better. Let it soak for a day or two, and then just wipe the parts free of rust when you pull them out of the jug you are using, and then place them into the proper sorted bin.

Thanks, Travis.  I really appreciate this feedback.  I am looking forward to putting together an electrolysis experiment.  

I'm also pleased to learn about the acetone/transmission fluid mixture, and I'll try it maybe on a small scale. But I'm not sure how enthusiastic I would be in the long run about disposing of gallons of the stuff by any of the practical methods available to me.  

Travis Johnson wrote:Incidentally I think you are doing the right thing. For years I thought my grandparents were silly for sorting this kind of stuff and keeping it, I mean the store is just down the road right? But as I have gotten older I have found myself doing the same thing. It is amazing how often I grab the stuff that my Grandparents separated and kept. A roofing repair job just needs a few roofing shingle nails. Sometimes I need five screws 3/4 of an inch long and no longer. And my bathroom door is a barn style door that slides effortlessly on a barn door track that we had on our old tractor shed...from the 1940's! All that stuff has costs to replace new, especially when you calculate the time and money just to get to the store.

It goes without saying, I think, that it's tough to spend hours and hours on a project like this without some of the idle brain time going to contemplation of the ethics, benefits, and costs.  Which is a fancy way of saying that the "is this useful or am I just doing an elaborate hoarder shuffle?" question is always playing in my brain at some variable volume, and I do wrestle with it.  Or as Grady put it:

But I have to keep asking myself, "when would I choose this used fastener over a new one?" And as one predisposed to hoarding, I have to keep reminding myself that the empty space is more valuable than this stuff.

Like any good permaculture question, of course, the answer is "It depends."  It's all a question of balancing resources and shortages, time and cost, opportunities and liabilities.  The answer differs even from item to item.  I paid two dollars for wooden bin full of detritus from a cabinetry shop.  It turned out to have about thousands and thousands of brand new shiny Phillips-head wood screws in it, plus assorted hinges, latches, castors, and other valuable cabinetry goodies.  But it also had several thousand ancient straight-slot wood screws in it.  The sorting was a job.  On my left hand is a bucket of obsolete screws I probably won't ever use, because zipping things together with a Phillips bit in an electric screw gun is so much easier.  On my right hand is shiny new screws worth at least one, and possibly a few, day's wages.  I wouldn't have done the work to get the straight-slot screw collection, but now I have them (and they are a lot more diverse in sizes than the newer ones) I'll probably keep them, because it's worth slowing down and using a screwdriver by hand (or a straight bit in an electric, very carefully) on two screws if the alternative is an hour spent going to the store and back.  

It's not just time and money that get saved when a store visit is avoided.  Again, it all depends on circumstances.  The guy whose shop I am in has some social issues.  He strongly likes to remain on his property.  If a store is too big or crowded, he may have difficulty there; it's not unheard of for him to abandon a shopping cart and walk out because he wasn't dealing well.  He would definitely use two obsolete fasteners instead of going to the store to buy nice ones that his screw gun can grip.  

Plus, we are quite distant from the store.  The local hardware stores are very minimal, and ten minutes away, one-way.  It's a half-hour to "go get a bolt" no matter how hard you push it.  It's a full two hours (round trip) to dash into a fully-stocked home center like Lowes or Home Depot.  

And finally, at the heart of the "hoarding versus thrifty saving" discussion is that notion of "the value of empty space."  There's also a phrase "land rich but cash poor."  I live on 40 acres; the shop I'm working in is on 80.  Our incomes are low and variable.  Cash is always tight today and might not exist tomorrow.  Good accessible storage is of course always at a premium, but there's an extent to which it's not hoarding if it's organized, labeled, containerized, and protected from the weather.  The security of keeping valuable goods that one might need, but won't be able to afford, in future?  It's real.  I have long felt that people who advise getting rid of valuable tangible goods unless you need them soon must be coming from a place of economic luxury, or at least economic confidence that their tomorrow will be as good as their today.  For most of us, it won't!

In any case, the internal debate has become moot in my particular circumstances.  I've only been working on this collection seriously for the last month or two, and it's already getting raided daily by one or both of us.  That's a lot of store visit time and gasoline saved!

 

I went out and took a picture of how my Lambing Barn conversion is going.

I kept (3) pens, boarded over the top, and put my tool boxes up there. Then underneath lined the pens with shelves so that I can have covered storage cabinets. It works well. There is a ton of storage space for my tools and materials.

I agonized on whether it was worthwhile to use nice wide pine boards for this project, but they came from a tree that was insect damaged and dying, so I cut it into lumber before it was all rot, so it used what could have been wasted wood. And there is something to be said for organization, even a tool shop.

To remove old paint (which is part of cleaning many items), I use a crock pot with a couple table spoons of original TSP in it. The newer TSP is different chemically and doesn't seem to work as well. Stronger solution works faster. The heat is a necessary ingredient. Cook the batch from a couple hours to a couple days - old oil paint can be _very_ tough, as can  milk paint. Brush off (dishwashing/vegetable brush works well), rinse. I guess you could just shake a bunch of fasteners in a big coffee can filled with rinse water; haven't done fasteners wholesale myself.

At this point either put in vinegar to de-rust or blow dry and paint or spritz with light oil.

- When steel is clean it can rust w/in minutes, depending on the grade of metal and the fineness of the finish. So dry everything immediately and coat with something so your clean stuff doesn't rust in your hand while you're admiring it.

- There can be a problem with de-rusting if the item retains an oil film.

- The chemical can be reused; dredge the old paint out of the bottom of the pot and cook more items.

My system is adequate. For de-rusting, electrolysis would be better. Tanks of a size to contain the item(s) covered with chemical but without wasting the chemical can require ingenuity.

Storage with wooden or other "soft" interior surface seems to reduce rusting of oiled tools and parts; maybe because the container surface absorbs some of the oil where there is contact; maybe because the container material reduces condensation and humidity within.

One reason to value old stuff is because the metallurgy of the fasteners can be better than what's commonly available now.

Slotted head fasteners are potentially easier to remove (as a rule) from a work piece than phillips head (easier than the other drive head configs, too). Paint can be scraped from the slot more easily to allow the driver to fit. Slotted heads can also _potentially_ be tightened more safely that phillips. But that all depends on a flat screwdriver that fits the fastener properly. I learned bench grinders as a kid by fixing flat screw drivers. Slotted heads are mostly slow and annoying to install compared with other drive types, but I would _soooo_ much rather find slotted fasteners when I had to take something apart w/out messing it up.


Cheers,
Rufus

Rufus, thanks for all those tips and suggestions!  But thanks especially for your remarks about slotted-head fasteners.  I am not skilled at carpentry or cabinetry; I struggle with these fasteners every time I encounter them.  But I think I may not have been paying enough attention to how well my screwdriver fits in the fastener.  There's a family-run hardware store in my past so I'm a lot better at identifying fasteners than I am at actually using them!

Dan

> screwdriver fit

The flat screwdriver can and should fit perfectly into the slot. The bottom of the tip s/b perfectly flat long ways and narrow ways, both - to the point that the edges are almost sharp. This maximizes the depth to which the side of the flat tip bears on the sides of the slot _and_ it makes it easier to feel when the driver is sitting square in the slot. A driver that "rocks" is much harder to get properly aligned than one that "clicks" or "knocks". The wide sides of the flat tip s/b perfectly parallel, or even a tiny bit "bell bottomed" toward the bottom to reduce any tendency of the screw driver to "cam out" of the slot like the phillips tips like to do. The tip s/b wide enough to fill the slot all the way long ways and s/b almost tight in the slot narrow ways.

Most flat screw drivers, whether new or not, don't actually fit a slot. I like to get the cans of old screwdrivers at garage sales. $2 for 10 screw drivers is about par. Then I have raw material to make tools that do the job I need.

When fighting old painted screws, you want a flat driver that's a bit too small for the slot but that has the perfectly flat bottom with sharp edges, with a long handle. Then you need a small hammer and utility knife. Use the knife to scratch around the circumference of the fastener head to break the paint bond. Then, one of the best ways to attack a painted slotted fastener is to use the driver "sideways". Position the driver mostly upright but rock it slightly (in the plane of the flats) to an angle which places one corner of the sharp blade where you want it to go; then user the hammer to tap the side of the blade near the tip and drive that sharp corner down and into the painted slot and push the paint out the other end of the slot. Do it again from the other side. You want to end up with a totally clean slot. This is a lot more controlled than using the driver like a chisel. The chisel approach can also be useful but you're more likely to over do it and make a great gouge where you don't want to.

The same tools and approach will help with any of the fastener types, but it won't clean them as easy. For the other types you need a very skinny flat driver, a couple of dentist's picks, and old  ice pick sharpened to a dangerous point and a lot more luck. But it's still worth spending a couple minutes trying to clean the fastener before going at it with an impact driver (and the proper sized bit).


Cheers,
Rufus

let us know what works best. interesting and useful topic, ive got all sorts of late model rust that could stand being removed. one thing ive found useful to solidify rusted object is a liquid rust converter, the kind you would use when restoring an old tractor with rust in gas tank. I've yet to find a way to remove rust on bulk scale like the problem you ask about. I've tried vinegar on rusted monkey wrench but was less than impressed with the results. checking the progress daily I ended up leaving it in the solution for about a month and its not much better than when I started.

I have not read all the replies, so forgive me if this has already been suggested. I'm envisioning a drum on its side with a few fins on the interior that rotates on a slight incline, very much like a clothes dryer, and nuts & bolts & whatever can be tossed in along with an abrasive like a coarse sand. A motor then rotates the drum, and the tumbling action + time might do a really decent job of removing rust. Then when parts are sufficiently cleaned, they could be dumped onto a set of sifting screens with the parts staying up top on larger hole screens, like hardware cloth, and with a couple increasingly finer meshed screens below, the sand and likely iron oxide particles would come out the bottom, ready to be used again. Being a dry method it doesn't seem to messy to me, doesn't require any acids, alkali's or toxic chemicals and could be a "set it and forget it" automatic cleaner. It seems like the sort of thing that could be relatively easy to make.

I don't understand why Tennessee isn't part of the rust belt the way rust seems to grow here much better than other parts of the country

That electrolysis video looks like the way to go. I love a set-and-forget approach. Build a rig for it once and you can do batches regularly, with no nasty gick to worry about.

If you are looking for a good low voltage DC supply, consider doing a hatchet job on an old phone charger. We use them to run old PC fans in strategic places to move warm air around the house from our woodstove.

My 2 cents here: You have mentioned bulk so I suggest electrolysis. I use a parts cleaning basket to hold the bulk fastetners (in my case parts from a blacksmith post drill) and a mixture of washing soda. The basket surface being the - contact of the items being cleaned a juggle now and then to stir it up. The solution not extremely toxic, unlike some plating solutions. A battery charger will work for a power supply. I have an electroplating power supply source and an area where I do that, so that is what I use. A resist on parts that have names/dates etc can be covered with a resist to preserve that if you desire.
I have an ultrasonic that works on rust but again what quantity are you cleaning?
Tumbling nuts and screws is probably not something I would do in bulk, individual pieces depending on what they were maybe. I mass finish jewelry and use different media: stainless shot, ceramic, abrasive plastic pellets of different configurations and walnut shells. an assortment of bolts would be banging against themselves accelerating degradation of threads.
For large parts I recently purchased one of the power washer siphon sand blasters. The tool connects to my power washer and siphons a blasting media like a regular sandblaster eliminating the need for a large compressor while reducing dust immensely.
Vinegar an option as well, Coke can do a surprising job on surface rust on chrome but have never tried it on anything else.
Travis' comment on a  mixture of acetone and atf is spot on.  I agree that this is one homemade tip that is far above any ccmmercial penetraing oil. I own a parts store and can use anything, but this mixture has proven itself on even salt water soaked parts. It is also an excellent gun cleaning solvent.

Posting this photo because it looks like art to me. Also, notice that there isn't any dry red rust anywhere.  Most of the collections I work with are powder dry, covered in red rust and spiderwebs and dustbunny lints, and very unpleasant to handle (my fingers get dry and rusty and painful).  This collection came out of a small Folgers coffee can that was in my father-in-law's tool shed.  I never knew him; he died in the 1980s and I met his daughter in 2003.  So this collection is at least 35 years old, by which I mean, it's been sitting in an outdoor not-climate-controlled but enclosed space since at least 1985.  Most likely, it was a thirty year old collection in 1985.  So, why so shiny?

Every other coffee can in the collection from that closet has the typical dry red rust.  There's half a #10 can full of nuts like that.  But this man was a union machinist for Boeing.  He also grew up as poor as poor can be, as a dirt farmer from a big family in the Oklahoma dustbowl.  It's pretty obvious to me that his coffee can of threaded hardware got routinely oiled.  Waste oil, a squirt now and then of 3-in-1, I dunno how he did it.  But these screws were mailed into the future with a rust resistant coating.  I'm convinced of that.

Its a treat to find a properly oiled old bolt, or even a crusty greasy one, and find its as good as new. Counters out the disappointment of finding a rusty bent bolt in the "good bolts" bin.

Your quest  got me going,  so I found myself looking into tumblers.

This is the cleanest, nicest looking of the diy tire tumblers  that I have found:



This guys tumbler is rough looking,  but he is doing exactly what you want to do with it:



Among machinist,  a lot of them use a concrete cleaner with phosphoric acid as the active ingredient  , Crete-Nu by Savogran, but I can't find it anywhere, so it's probably discontinued.
I believe the phosphoric acid cleaners are still available.

I have successfully used a rust remover containing mostly phosphoric acid. Not too aggressive and I never used gloves, but it requires manual work with a (wire-)brush. And once diluted it turns into fertilizer.

This is a grade 8 bolt, four inches long, one inch thick, made in the USA by Nucor Fastener.  It has a tensile strength of 150,000 PSI -- well over twice the strength of a "common" grade 2 bolt with no markings on the head.  It also has a history; those chisel marks on the head tell me a story of a long day, a torch, a broken cheater bar, a cold chisel, a heavy hammer, a lot of cussing, and, finally, a talented mechanic who not only knew how to break it loose, but had the self-control not to throw the miserable fuckin' thing as far as he could into the weeds when he finally got it out.  I never knew that guy, because I bought it from his estate sale, along with fifteen more gallons of similar hardware. I don't know him, but I've known plenty like him, including my own father.  

There's some corrosion markings on the bolt head and some rough spots on the threads, that I couldn't see under the original coating of rust.  Until I find and clean a matching nut, I won't know for sure if the bolt still threads.  A purist might prefer a new one, but a man who needs a good hard grade 8 bolt this size might decide to make it work.  Especially considering that a new replacement of this grade/quality will cost you fifteen bucks if you're buying in retail quantities.  At the tractor dealership, you would put in a new bolt and bill the client for top-notch perfectionist work.  In your own shop, well, it depends.

Anyway, this is an old thread but the problem of bulk hardware cleaning persists.  What really got me thinking about it again was the related problem of rusty tool restoration.  I didn't work in the shop much during the pandemic, because the biggest risk of forced exposure to the virus where I am is/was a chance encounter with the cops in a traffic stop. None of those guys were wearing masks or respecting social distancing.  So, until we got vaccinated, we weren't doing optional/frivolous driving errands, and the shop I play in is ten minutes away.  Didn't matter so much, because I wasn't doing garage sales either, so I didn't have the constant influx of "new" goodies to play with and clean up.  But now I do again.

I never tried an electrolysis experiment like we discussed higher in the thread.  No matter how you set it up, you're generating potentially explosive gasses (oxygen and hydrogen) at the electrodes.  It's easy to ventilate the risk down to virtually nothing, but in/near a borrowed shop it's not my place to be creating even tiny risks that are avoidable.  So that line of experimentation remains for when I get my own shop space.

By chance I came across some videos of vibratory tumblers being used to clean rusty hardware.  This was #6 on my list of approaches in the original post last year:

Dan Boone wrote:
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.

There's an almost-standard vibratory tumblr out there that comes in two sizes (small and bigger) from a variety of sources; it looks to me like there's one fairly expensive made-in-USA product (from Eastwood) and a whole bunch of copycat versions made in China and sold at places like Harbor Freight.  All the copycats may be from the same factory with different brand names on them, as is common with Chinese-origin tools.  The quality is said to be lesser.  

What I learned from my recent spate of video-watching is that using these tumblers to clean rusty parts requires some technique.  YouTube is full of unboxing-type videos where somebody gets the new toy, turns it on, dumps in the dry walnut-shell media (actually for polishing) that comes free with the unit, throws in some rusty bolts, runs it for a couple hours, pulls out the still-disappointingly-rusty bolts, and says some version of "well, they're better, won't need as much time on the wire wheel, I was hoping for more".  

Then, too, a lot of those guys are restoring classic cars.  They don't just want "enough rust removed so that the threads work again" -- they want mirror-polished bolts, every speck of rust and paint and original finish removed, so they can send their hardware out to be electroplated.  Vibratory tumbling can get you a long distance closer to that, but my research suggests it can't get you all the way there.  You still need a wire wheel or sandblasting step, and if you're gonna do that anyway, what did the tumbler really gain you?

Me, I just want all the crusty rust gone.  I don't do projects that depend on hardware with perfect finishes.  

Despite all the disappointed-newbie videos, a few -- very few! -- shop guys have videos that go further, experimenting with different tumbling media and especially with adding liquid (usually water) and soap (dish detergent or Simple Green most commonly).    That makes the project a lot messier!  But dust-free, so probably a lot safer.  




The consensus seems to be that "the green media" -- basically, hard plastic triangles impregnated with mystery abrasives -- is the best stuff for rusty bolts/tools, but it has to be run wet to be effective.  Downsides: the stuff is hideously expensive ($8-$10 per pound, and at the five-to-one recommended ratio of media to dirty hardware, you need 12-15 pounds to do a full load in the bigger-size 18lb-capacity tumbler) and worse yet, it's relatively soft, so it wears out fairly quickly.  (How many batches? Nobody will quite say, but not all that many.)  This would not work for me; beyond the expense, I am put off by the wastefulness of it. I need a thrifty media or none of this makes sense for me.

The second-best suggestion: "heavy media" such as ceramic triangles, cubes, and spheres, and/or tiny stainless steel pins (or old screws!) or good old-fashioned washed river gravel (some say, sand).  Always run wet, always run with soap.  Of course the stainless steel pins and fancy ceramic shapes are at least as expensive, when bought by the pound as tumbling media, as the plastic pyramids.  

Because the heavy media is heavy, you can't really put enough of it in an 18lb-capacity tumblr to physically fill it as much as is needful.  So there are different strategies for adding "bulking" media that is not so hard, but hard enough to be useful, and much lighter per volume.  Small hardwood shapes, a variety of plastic pellets, the glass beads used in sandblasting cabinets, even oddball stuff like bone chunks or the little cubes of tempered glass that you get when you shatter a tempered-glass panel.  

The deeper I got into the research, the more I kept hearing that, for the specific project of rusty bolts and tools, diversity in the tumbling media was the key, along with the soapy water.  Lots of different materials in all different sizes and shapes, the more the merrier.  As the softer items grind down into dust/mud, wash them out with lots of clean water (a bucket and screen is suggested) and replace them with larger items, so you always have a spectrum of size and varying textures.

And as for me?  I am garage-sale-man!  I can buy an endless amount of ugly ceramic tchotchkes for less than a dollar a pound, and do the world a favor by pounding them into "a diversity of sizes and shapes".  I can "make" tempered-glass cubes or small hardwood shapes.  This was beginning to sound more promising.  (I could also get endless small collections of plastic beads of various kinds for nearly no money, but I'm really not interested in using plastic media; manufacturing a microplastics waste stream is not my idea of a socially-useful upcycling.)

So, after all this research, I got it in my head that I really wouldn't mind trying out one of these vibratory tumblers.  And then serendipity! A side hustle paid off unexpectedly and I wound up with a couple hundred extra bucks in my mad-money account.  Was gonna go to Harbor Freight but my amazing online-shopper spouse found a Chinese-branded version (almost certainly identical) on Amazon for thirty bucks less.  Took a week to get delivered, but it arrived yesterday:



So far, I don't have any "light" media.  And -- potential snag -- the instructions with my unit warn that using heavy media can "prematurely" wear out the plastic bowl.  Fairly warned, I am.  But (a) bowl replacements are readily available; and (b) I am pretty sure I can fabricate a better bowl out of a steel pot if the wear issues prove too severe.

For media, I did order two pounds of the expensive small mix of ceramic shapes, just to get me started. Plus I had a four-pound jar of nicely washed and pre-sorted tiny river stones from, perhaps, a big-box store garden center.



As for ceramic tchotchkes, they come in varying degrees of hardness; harder (porcelain) is better, whereas the thicker stuff is often a softer stoneware with a good glaze.  I'm no expert, but I spent seventy-five cents last weekend at various garage sales picking out unloved and unlovable porcelain-looking ceramic items.  The chipped mug was the real heavy-porcelain deal; far harder than the buddha incense holder (?) or the swan candlestick, and rather difficult to smash up.



All told, the media I threw in weighed about eight pounds, of my 18-lb weight budget.  Throw in a pint of water, I'm at 9 pounds. Five pounds of rusty junk leaves room for up to four pounds of lighter media once I source some.  Click the pic if you want to see the rusty crusts in high-res horrifying glory:



So, as my mother's bread recipe begins, "into the bowl, dump..."  It quickly became clear that the concrete finishing tool didn't really fit; it was too large to become submerged in the limited volume of media.  So I took it right back out. Added the pint of water and a splash of Simple Green.  Started up the unit.



This all happened today.  I ran the tumbler for two hours.  Maybe one day I'll leave it running unattended; it is noisy.  But as for now, I don't trust it not to vibrate off its table onto the floor, or not to disassemble itself from all the vibration.  So I settled for a two hour test.  It's my expectation that really challenging items may need to go for 8-12 hours, but bolt threads might suffer and get peened over from a run so long.  I needed to look inside after two hours, for science; and I needed to go home anyway. Time to look:



And you know what?  My excessively rusty hardware is manifestly not done.  But the extent of rust removal, especially on the threaded items, is AMAZING!  I am ridiculously pleased.   I really can't wait to see what longer runs do for some of those rustiest pieces.  

I was also pleased that two hours was enough to take all the sharp edges off my porcelain shards, so it was safe to rummage through the media with my hands to retrieve my stuff.  I was not sure how long that would take.  

There are several rinky-dink "features" to this tumbler.  It has a drain hose that has nothing at the inside-the-bowl end of the fitting (like a screen?) to keep small media from vibrating down into the drain hose and lodging against the clamp.  The main handwheels (modern plastic wing-nut equivalents) that screw everything together are prone to unscrewing themselves under vibration, and need more robust lockwashers (which I have).  The gaskets between the bowl and the lid are not well-attached (not attached at all, actually) to either the bowl or the lid, so they keep flopping around and need to be secured with adhesive. Minor annoyances, but the mark of a tool either not-well-designed or that's been visited by the unit-cost-reducing suck-fairy.  

That said, I like my new toy/indulgence.  I think that if I baby it with great care, I can use it to easily clean big batches of hardware.  I will, of course, report back as experiences accumulate.  

On board ship we used 'bug juice', aka koolaid, to clean and brighten our brass fire nozzles. Cherry worked best. It would eat all the green verdigris inside and out. It's a very mild acid.
Some of the suck up divisions would follow that proccess up with a metal polish to impress the XO for daily inspections. (major eye roll) 🤣

I have been using the vibratory tumbler to good effect.  What seems to work best is to do my rusty hardware in runs about two to two-and-a-half hours long.  I've been doing before-and-after photo documentations of each run, which is a minor pain but the stuff needs to be laid out afterwards anyway to have light lubricant sprayed on it to prevent flash rust.  I propose to post the before/afters for a number of these runs so people can see how well it does or does not work.  

Bottom line, it works great at turning rusty stuff into working stuff to a certain point.  That amount of rust that makes old crap unpleasant to work with -- threads sticky, impossible to read the markings, feels nasty in your hand and stains your fingers red -- cleans up great in a single run.  The next level (black stains in the metal under the red rust) is variable; usually two runs is sufficient.  The level after that (deep pits full of rust with the black at the bottom of the pits) may or may not ever clean up, at least with the tumbling media I am using.  You'll see items appearing again and again in some of these runs as I keep giving them another pass through the machine. I take out the stuff I'm happy with and move it into the appropriate toolbox or hardware collection, then add more rusty "crap" treasures.

Third run. The ancient pipe wrench was nothing but pits and dents and more rust under the rust.  Running it last time let me see that it didn't have any interesting markings or promising restoration potential.  I tested it to destruction trying various methods of getting it un-seized, and I learned some stuff before it went to the scrap bin.  This run was also a test of aluminum cleaning (that handsome equine fence post topper) and a third pass for those handsome 1950s garden pruners, which I am trying to get clean enough to read the markings stamped in the metal.  Plus I was curious to see what would happen with that strange white corrosion on the (galvanized?) C-clamp.  

Notice that the really heavily pitted items aren't improving much any more.  It might be that sharper tumbling media (heavy ceramic triangles, or ???) would have a more aggressive chew at them, but I can always try that later.

Run number 4!  This was the the last pass (for now) for the 1950s pruners; they are now clean enough that I think it's worth taking them apart and running the two halves separately, but I haven't disassembled them yet.  They turn out to be "Briar Edge" brand, model S8, apparently dating to the 1950s or 1960s.  Briar Edge, near as I can tell, was a division or brand of the venerable American tool company Ames True Temper.

It's always a pleasure when random dirty metal comes out of the tumbler and I discover that it's pretty brass or bronze.  I guess I knew that the wing nuts from the ancient and horribly corroded aluminum pressure canner that I turned into a garden pot could not possibly be steel; the steel parts (like the brackets that held the wooden handles) were just a falling-to-pieces mess of rust.  But I did not think about it, just threw the wingnuts into the goodie bin.  

I cannot shake the feeling that I'm being abusive when I throw edged tools (chisels, carpet knife) and antique wooden-handled stuff like the screwdrivers into this process.  But honestly I am awash in the stuff and it's mostly not worth the time it would take to clean gently and individually.  A wood chisel that's shedding oxidized plastic whenever you touch it is, truly, garbage; after a pass through the tumbler it's at least clean garbage, allowing me to check markings, decide whether it's worth touching up the blade on the shop grinder, and so forth.  Most of the wooden stuff comes through surprisingly well, and (once clean and dry) seems worth oiling with linseed oil and keeping.

Not many repeat customers in run 5, just a few of the corroded wrenches and those die-hard square nuts, which I am really just using as a sort of experiment on how really old metal performs after numerous runs.  (If there's a practical use for 100-year-old square nuts, I haven't thought of it yet.)  

I continue to be impressed by how well the nastiest threaded hardware cleans up, although I am discovering that whomever created these collections was fond of putting bolts with boogered threads back in the bin.  Testing the threads on cleaned-up bolts has been added to the workflow process.  I don't own a set of dies for repairing dinged threads, but I'm sure some dies will turn up in the bottom of a rusty toolbox one of these days.  

The (galvanized?) pullies and cable clamps also clean up better than expectations.  I honestly expected the ancient zinc canning jar lid to be destroyed, but it cleaned up decently.  I may put it through another run sometime when I'm doing more aluminum and soft metals.  

This sixth run was yesterday, so I won't spam this thread again for awhile.  (I do honestly suspect I'm the only person crazy enough to find this interesting.)  

I feel like maybe the gross rust didn't get cut so well in this run.  Maybe my media is getting all the rough edges worn off and I need to add some sharper media.  Or possibly it's just that the stuff in this run was extra rusty.  Normally I wouldn't bother with rusty nails but this handful was particularly uniform and big enough to be expensive.  Anyway I feel that most of this run could use another couple of hours, so the next run will probably have most of these items in it.

All forty of those rusty sockets (and the nails) were in a container I bought for a dollar.  I'll get some value out one way or another!