Anyone use muriatic acid to remove surface rust? I want to clean up my lower control arms before reinstalling them and I want to get all the flaky rust. Any other options?

EVAPORUST

This picture is what my LCA's look like after soaking them out in a 5 gallon pail of Evaporust.
Looks like they were just made at the stamping plant.
Clean them up, squeaky clean with whatever solvent you prefer, then soak them out.

it works, but is nasty stuff to get rid of.
Citric acid works just as well. you can by it powdered and soak them in it instead.
While the rust part is just as nasty, the acid part is not as big of a deal.
naval jelly also works on surface rust.

The problem with Muriatic acid:
1) very strong and harmful fumes
2) it attacks the base metal
3) the items will flash rust instantly after neutralizing

There are much better products. My preferred removal method is:
step 1) blast of as much as possible
step 2) immerse or wash with a rust converter to get the rust that's in the pores. Allow this to dry, leaving the phosphate protective coating.

Try a product called Ospho. It works much better than evaporust.
These products are only intended for surface rust. Anything more and you will need to mechanically remove the rust then treat it.

Another vote for Ospho

I was introduced to Ospho by guy working on a tug boat. They use a needle gun to knock off scale and then treat with ospho before painting. He gave me two 5 gallon buckets of it and I have been hooked since.

Muric acid is good for cleaning out the water passages in your heads and block

When I would have a overheated beater id flush the cooling system with a gallon of ma with water and not leave it in long, just a couple minutes.

1/2 the time it worked. 1/2 the time it killed it off.

That was a long long time ago, id not do the same today, thats very bad stuff. Id look for other options.

I use Evaporust and it works great. The plus is you can pour the waste in the sewer drain once it stops working. Any type of waste acid here and I would have to take it to the chemical recycle building at the landfill.

I looked for naval jelly here years ago and came up empty handed.

If your control arms have major rust and pitting underneath I'd just find another pair.

They use it in swimming pools where people get it on there skin. Wear gloves if you have to put your hand in it, in other words use your brain. I've used every form of rust remover, I have vats of molasses, electrolysis tanks, muriatic acid tanks and I use osfo stuff. If you have a little or delicate part use the evoporust product $$$$. If you need fast, muriatic is the one, what you buy now is diluted but I still cut in half. Wash good when removed then spray with Crud Cutter, sold in paint stores, it will keep it from rusting back. Did my lca about three weeks ago, still no rust back, in about two months I'll paint. Remember, they all have there good points and bad points. After the muriatic been used awhile and lost its power I mix it with weed killer to get the stubborn grass out of my driveway. The ph just burns it up. I can hear the tree huggers now.

I don't know what the issues with disposal is. You dilute any acid with enough water and its harmless ... flush it down the drain !!!

Ive used phosphoric acid before. Its not as strong or quick as muratic acid, but Cleans off rust and leaves a coating to inhibit rust. Usally called prep an etch and found at many places.

More about the fumes: if you use it in a closed space like a garage, the fumes can attack everything metal in the area, if the exposure time is several hours or more.

After I left my shop for the day, a quart or two of vinegar leaked on the floor and put surface rust on every piece of steel in the room by morning. And this was just vinegar, not nearly as strong as typical store-bought dilute muratic acid.

Yes, Evapo-Rust isn't cheap, but all things considered, it's very popular for a reason.

I need more coffee this morning but i seem to foggily remember that Muriatic acid (HCL) can cause "hydrogen embrittlement" cracking even long after it has been used.

HBC can cause a steel part to fail far below its yield strength,
even below its fatique strength. Roughly this can mean breaking at 20% of the load you would expect.

It has other safety problems:

https://simple.m.wikipedia.org/wiki/Hydrochloric_acid

Osphro and Naval Jelly have been around for a long time and used by the US Navy

http://cameo.mfa.org/wiki/Naval_Jelly_Rust_Dissolver

There are links in my previous posts on rust removal on Evaporust about cheap extenders like vinegar of expensive rust removers.

I bought a gallon of Safest Rust Remover 4:1 concentrate but have not experimented with it yet.

My brother favors using a pneumatic needle scaler
followed by Osphro
or a rust converter.
The needle scaler handled right can add a "shot peened" strengthening effect to steel parts.

Don't weaken a steel part's strength while "pretty-ing it up."

I use Ospho.

http://ospho.com/

A little bit of side info:

All acids attack/remove rust AND the base metal to different degrees. Stronger = faster, but not really "better". In order of "acid strength", sulfuric acid (battery acid is about 15% sulfuric), hydrochloric (muriatic is 12% hyrochloric acid) > phosphoric acid > citric acid. I've never used ospho, but based on it's name it's an ortho-phosphoric acid based product (phosphoric acid).

All of these acids can be "neutralized" with baking soda making them OK to go down the drain in most places. fyi- it's good to have some baking soda around to neutralize any acid you get on your skin or on on concrete/other metal.

I've always used some type of phoshporic acid based product. Sulfuric is WAY too strong & hydrocholic (even 12% muriatic) is too strong too in my opinion, but yo might get away with it if you watch the parts VERY closely. If you aren't in a big hurry, you "might" be able to find some oxalic acid. I used to use that years ago to restore beer cans since it would SLOWLY remove the rust & leave the paint/ink on the cans alone for the most part.

This is why I sold my '72 SSP I was going to clone into a '71 RR. After sandblasting the entire front clip (not fenders), over several days with a Harbor Freight sand blaster, I left an open, empty gallon container of muriatic acid in the garage over night one night. Next morning I came out and every piece of metal in my garage was flash rusted. I was so disgusted, I sold the car.

Before:



After...



I did start blasting again, but then stopped in disgust and sold the damn thing.

Quitter !!