[Monkey Wrench]

dropping parts in an acid worked well for me but it produces very harsh fumes I have used muriatic acid on thicker parts it eats all the rust and finish away, it DOES attack base metal and it definitely eats aluminum. do not put aluminum parts in muriatic acid.
the "hook it leaves can help paint attach very well.

the less harsh system Ive used is electrolysis, a water bath a car battery and some washing soda, let it sit and bubble, the part that you are stripping should be the one to bubble otherwise reverse polarity. you need an expendable electrode, any good hunk of metal can work. think surface area. also proximity has an effect.

Im not sure how well that works on all paints or on powdercoated parts but when I tried it I was impressed, it did not attack base metal but removed the rust and any paint, only.

obviously you probably won't dunk the whole car body, you'd need a huge tank, and to remove almost every part. perhaps impactical.

but for parts that do come off and are rusted, I like electrolysis. cheap, no harsh chemicals doesn't overheat or attack the base metal like sandblasting abrasion etc.
I pull it out a few times to scrub with rags and baking soda, electrolysis leaves behind a black coating of some sort. I'll give parts a quick cleaning usually and for sure before painting. It can be a great alternative to using paint strippers , for some ( smaller) items.

stainless and also perhaps parts that are coated with zinc, Im not sure abou thtat reaction. be careful or research it.

you could find that electrolysis or acids may cause a reaction with zinc.( galvanized parts)

I once put washers that had a silver colored coating, the coating reacted with the acid, it produced a lot of heat and who knows what fumes. I'd avoid that. it might be cadiom or some other poisonoius substance so be careful with coated parts.

some websites seem to suggest using stainless as an expendable electrode for electrolysis, I have heard that stainless has some harsh stuff that should be avioded, so don't use stainless as your electrode, just use iron..

some use rebar, its cheap. Ill sometimes just use an angle grinder to clean my electrodes and use them over. a hunk of scrap metal will usually work fine.

if you use a car battery or a charger for electrolysis, careful not to short circuit the electrodes.


electrolysis is noce it will really clean the rust off well wothut a lot of harsh chemicals. I wan to make a larger bath for fenders hoods , doors, etc.

how do I make a tank? I was thinking plywood lined with plastic , then I had this brainstorm , Hey, how about if I just dig a hole and line the hole with plastic? then there is no need to build a tank and I can easily adjust the size and shape , Just need some heavy poly. fill the hole in when done ! I can pump it out if I don't want to release the paint chips and stuff into my own soil.

do your own research about the fumes and any hazards , I dont want to be liable and I am not a chemical engineer or a safety expert.

Electrolysis , Id definitely say it has worked well for me. Muriatic acid is horrible stuff to play with so I'd suggest not doing that, in some cases maybe it is ok. I had a lot of success but I'd also consider it quite hazardous.

muriatic acid is cheap and sold for cleaning old cement floors, prior to paint. it will also rust anything nearby with its fumes. I got a lung full of it, using it on a concrete floor, It was a horrible experience, so be careful with that one. baking soda will neutralize it. I'd keep some handy and I'd use it to neutralize any parts after.

I keep baking soda handy when handleing car batteries as a safety product, If I spill acid, I throw baking soda on it. once it reacts it is no longer a harsh acid. you can brush your teeth with baking soda, it is somewhat edible.

with the acid, when you take it out it wants to rust immediately much like sandblasting. with electrolysis I had no such issues with this "flash rust" issue.

hot tanks like used for engine cleaning, probably another method.

other acids, well you can buy autobody acid products for rust removal. Ive used "naval gelly" it worked somewhat, but takes time. some may include a rust inhibitor or a coating to prevent flash rusting.. maybe something like glycerine?

the rust amalgamator works well, particularily if you don't want to try to get every micro particle of rust . it turns it to a paintable black coating , easy to use. seemed to work well without going too crazy, just remove surface rust by abraision first. i find if i use 2 part epoxy I never see the rust return after.

quick and dirty grab a blowtorch not many paints womt burn off but heat can change metallurgy. go heating the side of your car you'll cause a buckled up mess, a bumper bracket? well maybe?
- in actuality if you find out when paint burns off and when metal starts to change its metallurgy you probably have a rather large window. if you are monitoring , the stage where the metal changes color you may be changing its harness maybe making it brittle. or too soft. if you heat lmeatl wiht a torch it will go through stages tan, blue violet etc. there are special "wax" crayons for checking temp they melt at certain temps.

for smaller items you don't want to scratch up you can try boiling the part in water that can in some cases work. it works for things like brass painted cabinet hardware, maybe not autobody paints.

- I am not in any sense , a bodywork specialist.

for those who are, What is your body shop using to deal with rust pitting and surface rust? Ihave a fairly nasty looking and very old firewall I want to remove rust from, then paint. what would the experts do?

I know there are amazing lasers now, but that is not in my budget.