Cleaning parts with Muriatic acid.

[Jeff]

I am currently working on restoring the dragsaw I got that I talked about in this thread.

https://forestryforum.com/board/index.php?topic=8422.msg172266#msg172266

some of the odd shaped parts that are impossible to wire wheel, lie the recesses of castings and the twisted chain and such I am cleaning using muriatic Acid.  I have a part, the shoe that is part of the clutch sprocket that really needs cleaning but my concern is, will muriatic acid effect break material? I am guessing its probably asbestos. Does anyone have an idea? The part is irreplaceable so I don't want to just chuck it in the bucket and try it.

[beenthere]

Is the pad bonded to the shoe?  Or riveted? 

If it is, I would hesitate dipping it in muriatic acid. 

Or try to pick up a junk brake shoe at a junk yard to test it out, if thinking they may be similar in bonding.   

[Jeff]

Its riveted.  I guess I didnt think about the rivets. my big concern was the break material. Tammy's head  mechanic at the bus garage says he can get anything relined, but I still hesitate on that. THe lining is really pretty good yet, its just that the metal part is so danG rusted up.

[old3dogg]

I can ask our lab guy tomorrow if you can wait that long.
We do a lot of studies on what chemicals do what to metals.

[Jeff]

Well, its been rusty for about 90 years, I 'spose I can wait. ;)

[old3dogg]

I will find out what I can and let you know.

[DouginUtah]

Jeff,

If what you are wanting to do is remove rust then you are using an inappropriate process.

You should be using electrolysis.

Do a Google search using electrolysis +rust +Westcott .

Also look at http://www.htpaa.org.au/article-electro.php

I am attaching a doc which I have in my archives.

-Doug

[Jeff]

Actually, for the large casting pieces I am doing where they are going to be repainted, acid cleaning is not a problem. Electrolysis might be something I would choose if this was an old plane or fine tool with engravings or etchings that I wanted to preserve. Certainly acid would etch and abrasion removal (sand blasting or wire brushing) could erase.  If I had access to a sand blaster for these parts, thats what I would be doing, but I don't, so elbow grease with a wire wheel and brush, and acid are perfectly acceptable choices.

[Jeff]

Doug, I read the attachment. I may try this on some of the smaller parts I have. Not sure if it would work with say, the wheels, but I might try them as they would take a LOT of acid to cover, and wire wheeling the spokes and rims would be an ordeal. Thanks!

[Jeff]

And Actually, it makes perfect sense to use it on the clutch part!

[Paul_H]

Yeah,thanks for the info Doug.I saved it for next time I deal with a rusty project.

Another thing I wanted to put out there...I have been using a 1/2 can of crystal Drano per 2 gallons of water in a plastic tub to dip parts and remove paint(usually many layers).I used it on most of the smaller parts when rebuilding a Model A years ago and was really happy with the results. And a few years ago we did a major reno on a house built in the 1930's and threw in all the metal light switch and outlet plates,door hardware and registers and furnace grills etc.They cleaned up to bare metal fast.

If there is something better or if there is a really good reason why we shouldn't use Drano it would be good to know.

[etat]

Well, it may be wrong but I've cleaned lots of parts before I knew better in muriatic acid.  ;D  I had a big plastic tub and I'd mix the muriatic acid with water and let it soak for a few days, keeping a check on it  off and on until it was shiny clean.  Once it comes out of the acid it needs to be neutralized immediately.  I would use soapy water and wash it down good and then sprinkle some baking soda over it and wash it again and scrub it real good and then primer and paint.  It seems like I'd use about a two or three gallons of water per gallon of acid.  Some rusty parts would take a few days for the acid to completely eat off the rust to shiny metal.  Use rubber gloves or the acid will burn a bit until you get it washed off of your hands, (don't ask how I know).  Not serious burns, just burning asensation. After a while the acid will neturalize itself in the water and be safe, (I'm assuming, best I remember it didn't even kill the grass) to pour out.

A  long time ago I've know of bricklayers that would wash dried mortar off of brick with rubber gloves and a brush  and acid and I'm pretty sure it didn't kill them either.

This all may be wrong, I'm not recommending it, but it works very well, and quick.

I've also used drano to remove paint.  Guess I just ain't real bright, but it does work.  Again wear rubber gloves. Take your time and don't splash any kind of acid on you. Always add any kind of acid to the water, not the water to the acid.

EDIT:  Sandblasting is a miserable miserable awful job.  I know the acid will not effect  plastic or rubber parts.  I don't know about brake material.

[CHARLIE]

What about that commercial stuff that you brush onto rust that changes it from iron oxide to iron phosphate, then you rinse it off with water.  Back in the early 1960's a man I used to work for used a product called Ospho.  It was as fluid as water and green.  Anyway, with something like this, you could brush it on just the metal parts and not on the brake lining.

[woodmills1]

Muriatic is a 25% solution of hydrocloric acid and water and is sold predominanly to clean bricks and mortar.  it also reacts chemically with metals.  It cleans them by actually removing some of the metal chemically and  releasing hydrogen gas, and yes it can burn skin and would be real bad for your eyes.

[Jeff]

I have been using long rubber gloves and goggles as I work with the acid. I am only using the acid to remove rust from areas that are to difficult to get to with a wire wheel on a side grinder.

[RoadKill]

Strong acid certainly works to dissolve rust, but it needs to be neutralized right away as the surface is left very reactive.  Strong base (Drano) also works, and leaves the surface more passivated.  You might consider a phosphoric acid based rust remover (I think "naval jelly" is based on phosphoric), as it leaves the surface with a stable phosphate coating.

Asbestos is pretty resistant to both acids and base, but can be dissolved but repeated switches from one to the other.  I would worry more about the rivets and the organic binders that hold the brake pad together.  If you are going to use the thing, you might want to consider getting it relined with a non-asbestos material for your health.  If you just want to look at it, I would brush on a rust cleaner and leave the asbestos pad alone.  Good Luck.

[Larry]

This old thread has a little info about electrolysis rust removal.

https://forestryforum.com/board/index.php?topic=6915.0

I de-rusted a tractor once with this method...one part at a time. ;D  Of course the tank was slightly bigger also...used a sheet of plastic inside an old stock tank.  One of those kiddie plastic swimming pools works well also.

[Paschale]

You might consider a phosphoric acid based rust remover (I think "naval jelly" is based on phosphoric), as it leaves the surface with a stable phosphate coating.

I have stuff called Rust Free, made by Boeshield thas is essentially phosphoric acid.  I used it to get a nasty surface coat of rust off of my table saw awhile back, and it works great.  Definitely involves a serious chemical reaction, with some nasty fumes coming off the table top, but man, it cleared that rust in no time flat.  It did take the sheen off of the table top, but that was no big deal.  I don't know what it would do to the brake.  I do remember that one of the selling points of this product was the phosphate coating.

http://www.boeshield.com/

[old3dogg]

Muriatic Acid at 100% will make asbestes brittle. Dilute to about 25%.
I wouldnt use it if the parts cant be replaced but if thats all you have?
We did a test today on asbestes and 50% MA  made it crumple and fall apart.

[Jeff]

O.K., Thanks old3dogg. I think the answer for this part is using electrolysis.

[old3dogg]

The parts that you want to clean are old and cant be replaced.
I would use the electrolysis.
Unless you have a "spare" piece to play with?

[Jeff]

Nope, no spares. These are pretty rare. I had a guy contact me and offer me 500 bucks for just the clutch sprocket as he has been searching for years for one. He found the dragsaw auction at the last minute and never got a bid in before it could close. Good thing.  :D He was enquiring if I was just a dealer that was going to resell.  NOPE!  ;D

[old3dogg]

COOL! Just be careful with the MA. It made the stuff we worked on today fall apart. I dont think it was as old as the parts you are working with.

[Jeff]

Using it only on heavy cast and steel parts.

[old3dogg]

MA will eat at metal but only if you let it sit in it for awhile.