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Mill scale prep.

Posted: Tue Sep 01, 2020 12:33 pm
by Timberjack
Just trying to help livin it up as the other post says, but whats your guys take on prep work ,myself i understand the need in most circumstances, but the other day i watched a youtube video of a guy doing his prep and soaked his parts in muriatic acid, never heard of it before, i know it will clean ,but would welding on the residue be dangerous, like brake cleaner , just trying to make conversation. maybe it would keep some kid from getting in trouble, if he reads some dos and donts.

Re: Mill scale prep.

Posted: Tue Sep 01, 2020 12:40 pm
by TraditionalToolworks
Timberjack wrote:Just trying to help livin it up as the other post says, but whats your guys take on prep work ,myself i understand the need in most circumstances, but the other day i watched a youtube video of a guy doing his prep and soaked his parts in muriatic acid, never heard of it before, i know it will clean ,but would welding on the residue be dangerous, like brake cleaner , just trying to make conversation. maybe it would keep some kid from getting in trouble, if he reads some dos and donts.
Citric acid works also and is much safer...you can get it from most homebrew shops. I use it to remove bluing from 1095 spring steel.

Re: Mill scale prep.

Posted: Tue Sep 01, 2020 6:21 pm
by sbaker56
Citric acid is the ticket, I'm dumb enough to not worry too much about Muriatic health wise, but not only will any parts you clean with it literally rust before your eyes no matter how well rinsed unless you aggressively neutralize it, the fumes will flash rust literally everything near by, if you step outside your workshop to clean a few pieces you're liable to find a fine layer of rust all over your tools the next day.

Re: Mill scale prep.

Posted: Tue Sep 01, 2020 6:26 pm
by Oscar
You never weld anything soaked in anything, unless it's dried water ;). But yes, muriatic acid, as awesome as it is to removing rust & millscale, has to be neutralized. I have some but have yet to need to use it. I need to set something up outside, that's for sure.

Re: Mill scale prep.

Posted: Tue Sep 01, 2020 7:16 pm
by Timberjack
Thanks for the responses guys, im the guy alot of younguns ask questions to around my parts, and if one ask this to me i could not have answer it. im on the same boat as you guys with chemicals and welding. it just dont mix. but i may try the citric acid myself , been reading up on it and it seems the warmer you get it the better.

Re: Mill scale prep.

Posted: Tue Sep 01, 2020 8:17 pm
by sbaker56
Timberjack wrote:Thanks for the responses guys, im the guy alot of younguns ask questions to around my parts, and if one ask this to me i could not have answer it. im on the same boat as you guys with chemicals and welding. it just dont mix. but i may try the citric acid myself , been reading up on it and it seems the warmer you get it the better.
Yes, it'll work exponentially faster, especially when fresh, when I'm mixing up a small batch I always try to used boiling water, And I'll often heat pieces I'm going to soak with a torch before putting them in.

Re: Mill scale prep.

Posted: Tue Sep 01, 2020 9:54 pm
by Poland308
Acid is acid. Once it consumes enough stuff it’s neutralized!

Re: Mill scale prep.

Posted: Tue Sep 01, 2020 10:41 pm
by JustTheDad
I used muriatic acid to remove mill scale from 2x2 square tubing and some 3/8 bar stock a couple of weeks ago. Just small pieces under a foot long to practice welding on. They were fine to mig weld after 15 minutes using 50% or so mix of myriadic acid. $5 in acid and $2 of baking soda to neutralize it saved me an hour, but mostly it was easier.

I actually took the pieces out of the acid put them in the baking soda water mix, took them out of that and rinsed them with plain water. Then slowly poured the baking soda water into the acid. Then added baking soda until it stopped fizzing.

Did all that outside and wore heavy chemical resistant gloves plus a full face respirator and long sleeves. Scary stuff.

I want to find a better acid resistant tub before I do it again.