About 30 years ago I happened upon a method to remove old paint and rust from old pressed steel toys and antique car parts. Hey believe me, Model A Ford spoked wheels can be a real pain to sandblast!
Not everyone has access to a bead blast cabinet or sandblaster and using Naval Jelly never seemed to accomplish much, plus keeping paint remover on vertical surfaces always seemed to be an issue, so I discovered a much easier way to remove paint and rust. It's what I refer to as "The Lazy Man's Way to Paint and Rust Removal."
First, go to your local bargain store (Wal-Mart, Dollar General, etc.) and buy a large 44-50 gallon plastic container (the kind college kids like to haul their clothes back to the dorm in or take to summer camp - it comes with a snap-on lid and is about the size of a footlocker). The lid part is important and I'll tell you more about that later. You can get a garbage can if you wish but I prefer the rectangular container. Mine is a 44 gallon "Storage Tote" and has a snap-on lid that is hinged in the middle which makes it convenient to open just one end to remove your toy/car part or just check its progress. As long as you are in Wally World or Dollar General, buy some rubber gloves - preferably the long type gloves ladies used to use when they did dishwashing by hand (what's that?). ha I would also get some safety goggles if you don't already have some.
While you are out shopping for the plastic container, swing by your local hardware store (Home Depot or Lowes) and buy two gallons of Muriatic Acid. It should be in the outdoor/garden section because it is used to treat swimming pool water.
When you get home, place your plastic container on a porch or patio area (or out behind the garage out of Momma's sight) and grab the garden hose. Fill the 44-50 gallon container about half-way full with ordinary tap water from your garden hose. Then put on your new pair of rubber gloves and carefully and slowly pour the Muratic Acid into the water trying not to splash it on yourself. Read the warning on the container and you'll discover that Muratic Acid is really Hydrochloric Acid so BE VERY CAREFUL! NOTE: Always add the acid to the water; never add the water to the acid! And don't stand directly over the vat as you pour the acid in - the fumes will knock you over!
While you might think this stuff can't be very harmful since it is added to swimming pool water that people swim in, take note that it is also used to clean brick, stone, concrete, etc. So, be careful where you spill it - it etches concrete.
Two gallons of Muratic Acid added to about 22-25 gallons of water is about the right recipe. (I have been advised by one eBayer who read this guide that he used a 5 gallon plastic bucket with one quart of muratic acid and it worked great to strip a '56 Tonka pickup. It all depends on the size of the toy or part you are going to strip. If you are planning to strip a Tonka semi trailer or larger Buddy L trucks, or you are like me and strip several toys at once, the large 44-50 gallon tote is the way to go.)
Grab a supply of old coat hangers and straighten them out and use your pliers to make a hook on each end. Hook your old toy part with one end of the coathanger and use the other end's hook to slip over the edge of the container (you'll be glad you did that later when you are trying to fish out the part). Be sure to use the lid and close the container to protect unsuspecting wildlife or small kids while you are away.
Depending upon how many coats of paint you have to deal with or how much rust you have, I have found that leaving something in the vat overnight is usually sufficient. There have been cases where I have left the part in for 24 hours and even as long as three days to get rid of the rust and paint. The sheet metal on old pressed steel toys such as Tonka or Buddy L, etc. survives the bath great.
When it's time to check the progress, don't forget to wear your rubber gloves and simply pull the part out of the container and hose it off (this is where the safety goggles come into use). I use a high pressure nozzle on the end of my regular garden hose and the paint just glides off and the rust has disappeared! You may use a power washer if you have access to one. Either way, the old paint just floats off and there is no rust left.
Dry off the part immediately with an old towel and prime it or it will begin to rust again immediately. If you decide to wait a day or two after drying it off before priming it, you might need to use a rotary wire brush to clean off the new surface rust. Wipe it down with paint thinner to clean off any dirt and residue and prime it. I like to wet sand my primer prior to painting to get the smoothest paint job possible.
You will be amazed at how successfully this method removes all paint and rust from your old toy or old car part. Now you can use the "lazy man's" method of removing paint and rust and be doing something else you enjoy while your acid bath is doing all the work for you!
Several readers have asked how long the "soup" lasts and how often it should be replaced. It all depends on how many toys you strip and how "yucky" the mixture becomes with old floating paint and rust in the soup. It doesn't lose its potency over time so I generally mix a new batch about every six to nine months, but then I strip lots of toys. If you will keep the container covered to not only protect children and wildlife, it will hold down the evaporation rate and you shouldn't have to change the mixture very often. When you do have to change it, muratic acid is pretty inexpensive (generally less than $10 for two gallons at Home Depot) and water is cheap, so it's all up to the individual. Newly mixed "soup" is clear and it's easy to see the progress of the paint removal while the toy is still submerged. If your mixture is old and has lots of old dead paint floating in the mix, it might obscure your ability to see the progress on whatever you are stripping.
I have received many questions regarding how to dispose of the old "soup" and as I mentioned previously in this article, it will kill grass, therefore I find an area where there is no grass such as the unpaved alley behind your home or along the side of a driveway (it works great as liquid edger but don't get it on the concrete drive or it will leave a stain). Personally in my part of the world we have lots of fireant mounds and I find personal satisfaction in giving the ants a nice bath with the old mixture - it might kill the grass but it also kills the ants! If you are overly environmentally friendly and don't want to pour it on the little six-legged critters or kill any of your grassy areas, you can fill several old milk jugs with the old soup and haul it to the local used oil disposal place (city landfill). Remember to wear your rubber gloves and you'll have to use an old saucepan as a scoop or ladle and fill the empty milk jugs using a funnel. If you don't have 22-25 empty milk jugs around the house, you can go to Home Depot and get some 5-gallon buckets (some restaurants sell them cheap after they empty them of pickles or whatever).
WARNING: This method works only on pressed STEEL toys and STEEL car parts; do not put die cast aluminum toys (some Structo trucks and Smith Miller cabs) into the acid bath or they will dissolve away. If you are unsure of the metal type, use a magnet - if it attaches to the part it is steel; if it does not, it's aluminum. I dropped a Doepke Caterpillar D-6 Bulldozer in the bath since I knew it was pressed steel however the air cleaner attached to the dozer was cast aluminum (pot metal); the dozer itself cleaned up nice, however the air cleaner dissolved. If in doubt, always try the magnet test first! Another eBayer commented that this acid bath works great on the sheet metal parts of early Buddy L trucks however he advises not to drop the frame into the acid or it will dissolve the rear axles and the rivets which hold the front steering assembly (I sell new rivets in my store).
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Enjoy! Fred Carlton ~ TonkaToyMan from Tonka Town