Remove rust while preserving millscale

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Hello all, I'm wondering if there is some kind of solvent that I can use to clean off some light rust from a project. But for the moment I'd like to preserve the mill scale because I'm not planning on painting it for the time being. I'm trying to keep the look uniform and not have bare patches of steel from where I used a grinder to brush or flap disc the rust. Thanks Sent from my iPhone using Tapatalk
Reply:Naval Jelly?
Reply:if it is very light. try a wire brush on an angle grinder or drill etc…. Just don't be aggressive with it and the scale should stay- Christian M.C3 Welding & Fabrication - CNC Plasma Cutting-Mobile Welding-Custom welding and fabwww.c3welding.com
Reply:Thanks. I had been using some degreasing wipes, and then I remembered I had a copper wire brush for the impact driver. That did the trick like u said. I also picked up one of those resin-plasticy looking Brillo pad things for the angle grinderSent from my iPhone using Tapatalk
Reply:Originally Posted by SeawalkerThanks. I had been using some degreasing wipes, and then I remembered I had a copper wire brush for the impact driver. That did the trick like u said. I also picked up one of those resin-plasticy looking Brillo pad things for the angle grinderSent from my iPhone using Tapatalk
Reply:SeawalkerWorking - on retaining, and/or acquiring, an original metal surface is complex. You haven't supplied enough [any] info as to what you are doing to get a qualified answer.What - metal and condition are you starting with, what processes is it subject to, and what do you want it to look like when finished?Opus
Reply:If you have just a blush of rust, try some Barkeeper's Friend, maybe with a fine Scotchbrite pad.  The Oxalic acid in the Barkeeper's Friend will dissolve some rust if you let work a bit."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Would an electrolytic process work for you?
Reply:I was going to mention the electrolytic process. Apparently it doesn't work on mill scale like it does on red rust (what blessing if it did). Just no personal experience."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:It the rust is heavier than as described above as a "blush", then consider attaching a fine wire wheel to your angle grinder and applying it lightly.....Wire wheels tend to polish mill sale but not remove it....Test it on scrap and see if you can obtain a finish that provides the look and protection you desire....In my experience, I couldn't even dent mill scale unless I used a VERY aggressive wire wheel and lots of pressure where the wires quickly broke off and lots of the scale remained.....Them wire wheels ain't cheap so never tried that again.It all depends on the level of rust, where you might have to resort to mechanical means verses chemical, plus also the location where it's not possible to get a wheeled tool in there.Last edited by wornoutoldwelder; 09-27-2015 at 03:27 PM.
Reply:Have you considered OSPHO (phosphoric acid) ?   It turns rusted spots black and would likely blend in with the mill scale.30+ yrs Army Infantry & Field Artillery, 25 yrs agoMiller 350LX Tig Runner TA 210, spool gunLincoln 250/250 IdealArcESAB PCM 500i PlasmaKazoo 30"  vert BSKazoo 9x16 horiz BSClausing 12x24 lathe20T Air Press
Reply:Just wipe some muriatic acid on and rinse it off in a few seconds once the surface rust is gone.Welding/Fab Pics: www.UtahWeld.com
Reply:I heard wd-40 works good. I'm gona try it today and post my results. That's what a guy told me that works at a outdoor steel yard
Reply:WD-40 ain't ****. A little oil in some paint thinner.  It is good for some light degreasing but not much more. It has nothing to do with dissolving rust. Zero."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Well for me, many pieces I have that I want to preserve I just electroplate them....at my own plating company. .   However I realize that not everybody has this luxury nor the money to do the same.  With that in mind, I would just either use liquid wax on the metal (i.e. Floor wax in a 5 gallon bucket or larger drum).   Submerge the parts into the wax or oil and then store it in a relatively dry area.  Good old WD40 on the steel works great too.  The two processes will prevent surface rust from forming until you need it for a project.  Acetone or denatured alcohol to wipe it down prior to fabbing it up for a project is your friend.Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:Thanks for the suggestions. I'm talking about the kin of Steel that Rust and has mill scale. Hot rolled and mild carbon. I used OSPHO on many steel hulled boats to convert rust. I hated that stuff. And have many holy shirts to prove it. But it does the job. Side topic, I coated newly welded steel panels on hulls with expoxy paint and they rusted anyway 3 years later. I should have removed the mill scale I think. They were rust buckets anyway and are now sunken artificial reefs off the coast. I wound up having to go down to white metal anyway because there were too many tiny rust pits. So that's that. The Norton pad,heavy scotch bright did take the alligators hide off like you said. Sent from my iPhone using TapatalkLast edited by Seawalker; 09-29-2015 at 01:56 PM.
Reply:Originally Posted by storemanHave you considered OSPHO (phosphoric acid) ?   It turns rusted spots black and would likely blend in with the mill scale.
Reply:OH man am I dumb.....  I just re-read the title of your post.  You're looking for a process to REMOVE the rust,,,,but keep the millscale.  Well, in the plating business we use a lot of nitric acid as well as hydrochloric, depending on the type of metal and what it will be used for in the future.  It removes some rust, but not all of it without affecting the mill scale.  Wire wheel is the best bet, but it takes a lot of millscale with it.  Red rust just sucks, doesn't it?Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member