It is currently Mon Oct 15, 2018 3:35 pm


Anyone here using Citric Acid?

CNC Plasma Cutters are amazing and there is always plenty of knowledge to share and discuss. Use the CNC plasma cutters general forum for this purpose.
Posts: 26
Joined: Mon Feb 12, 2018 9:13 am

Anyone here using Citric Acid?

Postby JohnnyC » Sun Jun 10, 2018 8:22 pm

Anyone using powdered citric acid to clean mill scale? I have been using it and it works good at first but if I leave it in the vat sometimes i get buildup on the topsides. I placed a small pump in there to circulate the water but don't seem to help. I don't know what ratio I should mix it also. Any advice would be great. How often do you have to change it out?
Thank you in advance.

Posts: 142
Joined: Sun Jan 12, 2014 2:30 pm

Re: Anyone here using Citric Acid?

Postby islander261 » Sun Jun 10, 2018 10:48 pm

Citric Acid is used as an environmentally friender method for passivating stainless steel. It is used at an elevated temperature for this. I tried it a few time for removing heat discoloration and cutting"sugar" from the edges of plasma cut parts with little success compared to using phosphoric acid. If you look online for citric acid passivating you should get plenty of reading material. I have never tried it for carbon steel but I would think that it will not work as well as mineral acids. If you are looking for an alternative to mineral acids you might want to try electrolytic rust removal using washing soda and a carbon anode.


Posts: 26
Joined: Mon Feb 12, 2018 9:13 am

Re: Anyone here using Citric Acid?

Postby JohnnyC » Mon Jun 11, 2018 9:34 pm

Citric Acid cleans Mill Scale off Hot Rolled very well at first. t will remove the scale in a few hours at first mixture. I talked to a guy here where I live that said he uses it but I didn't get his name or contact info. I don't like using the toxic acids. I'm just trying to figure the mixture and length of use. I use it in a container sitting out in the sun so it does warm a little now that summer is here.

User avatar
Elite Contributing Member
Elite Contributing Member
Posts: 1411
Joined: Mon Jan 09, 2012 4:30 pm
Location: New Berlin, WI

Re: Anyone here using Citric Acid?

Postby tnbndr » Tue Jun 12, 2018 10:23 am

I don't like the toxic acids either, but I use Vinegar instead. The stuff you buy in the store is 5% I think. I found a local pickling business that sells me 12% when I need it. It works good, usually overnight. I don't reuse it so not sure how long it would last but I would think at least a couple of uses. Never tried Citric acid.
LDR 4x8, Scribe, DTHCIV
DeVilbiss Air America 6.5HP, 80Gal., 175psi, Two Stage
[email protected], [email protected]
Miller 211
RW 390E Slip Roll
AutoCAD, SheetCAM, Mach 3

Posts: 15
Joined: Wed Apr 18, 2018 4:45 pm

Re: Anyone here using Citric Acid?

Postby slamwilson » Tue Jun 12, 2018 1:30 pm

I have never tried Citric acid or Vinegar, sounds interesting... I use a 60/40 Muratic acid and water mix in a garden sprayer, I spray it on, leave it for 10-15 minutes, rinse well with water, scrub it lightly with a Green scotch brite pad and its good. Muratic straight is very nasty with the fumes, mix it with water and its not so bad. The attached pic was done that way...

You do not have access to download this dxf file.
Become a Contributing Member to gain access to the thousands of files shared by our members. Click Here

Return to “CNC Plasma Cutters General Forum”

Who is online

Users browsing this forum: Google [Bot] and 13 guests

Easyscriber engrave attachment for Hypertherm torch's