A downside to muriatic acid.

Last night Dan and I went to the shop to work on our cars a little and when we walked into the shop we found every bare metal surface in the shop covered with a light coat of surface rust ! I'm talking about the bare metal on my rpu project, Dan's new metalwork on his Mustang project, the tops of our bandsaw, the rollers and shafts on the bead roller, literally every piece of bare metal had brand new rust on it. These parts have been laying in the shop for months without rusting as long as we didn't touch them with our hands.

Dan had just been at the shop the night before and all the metal was clean and rustfree, and our shop is dry as a bone, no leaks. Something had caused the metal to rust overnight. I went into Don's shop next door and the bare metal in his shop was spotless, even the bare metal roll cage in his Capri, nothing was rusty so it was limited to our portion of the shop.

As I was walking back to our shop it suddenly dawned on me.........MURIATIC ACID !!!!!!! Dan had cleaned some mill scale off of the steel plates he was cutting for his Mustang tub job, and he bought some muriatic acid to soak the parts in. He was telling me how it removed all the mill scale in about 10 minutes.

I read the label on the bottle and it said "Highly corrosive to steel, wood, plants, etc, and fumes will travel a long distance." Evidently the fumes from the acid permeated the shop and attacked all the bare steel. I spent an hour with a huge bottle of WD40 and a rag, trying to minimize the rust until I can get to it and clean it off with a DA.


Don

 

Its always tough to learn the hard way .... notice swimming pool equipment, pumps and ladders are made of stainless steel?... the stuff is also hard on cement floors.

.. it might be beneficial to neuteralize the rust areas with baking soda with your DA chores Don.

 

YEP! that's bad stuff. I learned it the same way, only with two NOS quarters in close proximity . They survived though

 

Ah yes... Did this to a 34 once...
Once. Lots of metal prep, scotch brite, anger.

 

OH MY!
Thats horrible man, serious kick in the jewels right there.

Hope it comes off easy enough.
I woulda never thought of that, lifes learning cure Eh?

Good luck

 

I am guilty of the same and I am in the swimming pool business! I acid washed some mini bike parts and forgot the little tub of acid. The next day I had the biggest mess to contend with! Don't ever get lax with that stuff!

 

Oops! I remember learning that lesson in the 70's when I had some in the shop to clean brass parts. Yeah, that stuff is highly corrosive on or around any ferrous metal. Phosphoric acid is the only acid I use.

Even if you clean the rust off it's possible you may have to neutralize it or the rust may come back.

 

Been there-done that using the stuff to clean/scour the floor from a previous tenant that is a filthy, pack rat old man. You should see his yard. Whiskey is a hell-a-drug.

 

It's a last resort kind of cleaner for me, I did radiator repair for a few years and used it for a final cleaner before soldering. The tools in that area were consumed in use. A friend used it to clean the cooling system passages in an engine block. Even after a thorough rinsing with water, in about six months after assembling the engine and running it the acid in the poors of the cast iron soaked through the block and began to coat it with rust right through the paint.

 

I use it all the time - to take off mill scale (because cold rolled is hard to find here in thicker gauges) and remove galvanising from bolts etc if I need to weld them. Works great, but it is ALWAYS done outside...

Your panels should clean up real quick with phosphoric and some scotchbrite though.

As an aside: you will get exactly the same thing happening if you weld close to metal that has been treated with some rust converters - the milky white stuff that turns purple/black on treated rust.....
If you are welding on something and get an acrid,almost vinegar type smell, make sure to get the area ventilated as quick as you can.

 

Since my father had a gallon of it lying around to clean brick mortar and I was an unemployed 19-year-old carpenter apprentice, I used muriatic acid to clean a bunch of bolts and small parts on my '40 Ford after I first got it in 1980. Stupid mistake - left them in an open container, and after a while drained off the acid leaving clean bolts...but didn't bother to rinse/neutralize afterwards. Still have the rusty bolts and brackets in a rotted-out coffee can to remind me not to do this again. At least Evaporust won't rot everything within a 50-foot radius.

 

When I painted my garage floor, per instructions I cleaned first with muriatic acid.the next step was to neutralize the acid with amonia.

Your mileage may very

later jim

 

I worked in a place that had etch tanks on a chemical film line for years. The tanks were removed, clean fill brought it and everything okayed by inspectors. A new slab was poured and a machine shop was built on the site.

It didn't take long for any exposed steel to start rusting. Machine tools, parallels, precision measuring equipment. The fix was to move all the expensive inspection equipment out of the area. Nice.

Bob

 

I will only use it to clean rust stains off the driveway. I also learned the hard way. I left a closed jug in a Corvair that I was fixing up. It pitted all the chrome bezels on the dash and all of the door handles. Never again will I have muriatic acid in the shop.

 

I left a small pail near some cans of spraypaint.... You could imagine the mess I encountered a few weeks later.

 

I owned a retail paint store and carried muriatic acid,,at one time I received a case of 4 gallons on a Friday and was unaware that the plastic top had cracked on one of the gallons in the case.

I opened the store on Monday and instantly knew what it was,,every paint can in the store had a light surface coating of rust,,I decided that day that I wouldn't stock muriatic acid in the future. HRP

 

I've used muriatic acid many times with great results, cleans rusty pitted metal to virgin material.
What surprises me is you guys use it inside, couldn't handle the fumes myself as it even burns the air when you take the top off.

 

I don't like it.im getting to be forgetful and I aint about to use something that's gonna mess up more than I can fix...

 

Yep. Even in a closed jug it'll cause damage.

Had a jug in a metal storage cabinet. Tightly capped.

Months later when I went for something in the cabinet and every metal surface around the jug was toasted. Paint peeling, tubercles of rust.

It permeates plastic over time and does its dirty work too.

 

Wonder what it does to your lungs.

 

Don
You left out that it burns your nose.

Sorry that everything is fucked up friend. Sounds like steel wool and light oil is in your future.

 

I used to haul the stuff in Bullk for industry ,Muriatic acid ( proper name hydrochloric acid) is made from hydrogen chloride gas and water , poisonous stuff , especially the vapors , the vapors when thy contact moisture reform the vapors into acid in your lungs and burns the tissue and causes pulminary edema ( water in the lungs ) and brings on in our trade what we call Chemical Pnuemonia , you will get a cough that will last several days to a week from the excess water . always wear a acid resperator when working with this product no matter how small the ammount . and never work in a closed room with the product always have a fan move the vapors out as they are heavier than air and tend to collect where there is moisture .

as for phosphoric acid its just as bad or worse for the human body , but not metals

always were PPE when working with chemicals. a few minutes of not wearing the stuff and inhaling vapors can lead to years of suffering ,and some times the damage takes a while to start showing . and I am not talking about in the ammounts I used to work with , its in the little ammounts .

 

I use the stuff frequently, but I'm always extremely careful with it, and store it outdoors, and away from anything it could possibly damage. But, I've learned the hard way too. My Mother had a mole problem over at her house, and I tried every "trick" trying to get rid of them. The fumes are just about impossible to tolerate, and VOLATILE, meaning explosive! I had decided to fumigate the mole tunnels with Muriatic Acid fumes. I made up a container from a gallon sized bleach bottle, and tossed a bunch of rusty and galvanized metal into the jug. The plan was to attach a hose to the top of the jug, and had a section of PCV tubing glued to the side to which I attached the exhaust feature of my shop vac. Now, there was a hedge around Mom's front yard, and the moles were doing their most recent damage outside of the hedge line. Vacuum set up inside the hedge, hose through the hedge to the jug, and stick the end of the hose into the tunnel. OK, ready to go; partially fill the jug with Muriatic acid, and cap it off, run down the hedge line to the end, and around the bushes back down to the shop vac. The nano-second I hit the "ON" switch I knew I had made an "error". BOOM!!!! Thankfully, like all Craftsman Shop Vacs, the top of the vacuum retainer clips had been broken off from years of use, all 4 of them. It "only" blew the lid off; if the retainer clips had been intact.................................. What happened was, the fumes backed up the hose into the shop vac, and the spark of the electric motor set it off. Sort of a Rube Goldberg apparatus. I still have the shop vac, and this was in the fall of 1984, and it works fine still. Now, everybody laugh at my foolishness, but learn from it; I sure did. Butch/56sedandelivery.

 

Was just thinking of using this stuff in my small two car shop. Glad I read this first...

 

I only use it out side, but it works wonders

 

Speaking of fumes and on a similar bent -- My father apparently had left open a 5 gallon pail of carb dip in the corner for a while in his enclosed garage that also had a small roof (flashing) leak so it would be humid and dry out slowly after a heavy rain.

Unfortunately my tool box and a few other things were there in storage and guess what.....Half the paint and powder coating was gone from my stuff when I went to move them to my house. :-(

Al in TN

 

butch what you did was make Hydogen , the old way of doing it is to use zinc and mix it with the HCL , and the hydrogen liberates from the chlorine . so you wind up with 2 hard to handle chemicals .. and we all know what Hydrogen does with electric sparks ...Hindenburg anyone ??? LOL

 

thats the methylene chloride in it , A.K.A. aircraft paint stripper . don't know of any paint thats imune from the fumes of that stuff .. and the fumes are toxic as well , turns to carbon monoxide in your bloodstream , and can be asorbed readily thru your skin .. in the tank business we used it for stripping epoxys and resins out of trailers , no liquid needed , just open the top of the tank , toss in 5 gallons close the lid park it in the sun for a hour and let it get warm . and the resins would soften to jello . and wash it out with hot water .

the thing with chemicals guys is if you want to know its toxicity, Material data sheets are on line from the manufactuers and publicly available ..

as for washing bolts in acid thata nono , unless you rinse them and put them in a oven at 160* to drive out the hydrogen , it will make them brittle in the threads

 

I use vinegar to get the mill scale and rust off. Just takes a little longer soak time. Works good.

 

I've had a quart plastic jug of the stuff in my garage cabinet for 15 years. Just this winter I noticed the tops of my paint cans had rusted. One can of black paint weakened and exploded in the cabinet making quite a mess.

It wasn't until I read this post that I realized what the root cause was...Now I need to dispose of the acid..

Thanks for the post.