Mill Scale Removal question

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I'm attempting to remove the mill scale from my welding table top which is 5/8 HRS. I started with Rustex rust converter, which is a phosphoric acid rust converter,  with very little success.  After a day of repeat applications, scraping any loosened debris off, followed by some elbow grease and scotchbrite pad, and reapplication of krud cutter rustex, and overnight application, I'd barely made a dent.  So, I bought muriatic acid, which shows 31.84% acid and mixed some into a quart of water, which was probably only a few ounces.  Applied to the surface, covered with some 6 mil plastic to keep from drying out, left for 2 hrs, and almost nothing.   So I added a few more ounces to the previous mix, and re applied. Several hours later, little to no effect.  So, more acid, another re application, covered, and left overnight.  This AM, still little to no difference.  So, i went with a 1:1 ratio acid water mix,  re applied, covered, went to watch the PACKERS WIN (I know, not a pretty game)!  Back this afternoon and still, little result. This is what I'm left with after the last 2 days of acid and scrubbing with Scotch BriteIs this from not having enough acid solution to interact with exposed surface area?   Or do I have some sort of "super scale?"For reference, in the first mixture of acid I placed a piece of flat hrs steel to gage effectiveness, and was easily able to wipe the mill scale off with nitrile glove after 20 min. The scale is literally about 1/64-1/32" thick or so,  or was originally. I'm making progress I guess, I'm starting to see the grain in the plate,  maybe my expectations were a little to high using the muriatic acid?Last edited by Teggy1; 10-11-2015 at 06:30 PM.
Reply:Sorry you suffered all this time, effort and expense so far, but maybe now you are open to answers and suggestions.The reason that plate has mill scale is because it is supposed to have it, being HRS.The reason you can't dent it chemically means it is acting as it should.Mill scale is a predictable and often desirable by product of the process used to form steel when done so in the economical and precise, modern hot rolled fashion...The hot roll process not only can be expected to produce mill scale, but it should also be expected to produce steel with very consistent "workability" traits that also might be beneficial and cost effective for you in the end.So ok, you got a large flat piece of steel that is doing what it is expected to do, and you want it to not do that particular thang with mill scale.Simple answer is to grind  or sand/media blast it off...I didn't say the easy answer, I said the simple answer...Go ahead and try chemicals, then try paint remover, then sanding, and try witchcraft and fire and religion, but in the end you will end up grinding or blasting it off, and be finally done with it...And oh, please skip wire wheels because they are just too danged expensive to waste.
Reply:My question is why are you trying to remove the mill scale from your welding table in the first place? Scale will not interfere with grounding at all
Reply:Was there a point at which I  indicated I was not receptive to suggestions, or indicated feedback was not welcome? I fully understand what mill scale is, how it is produced, why its there, why it is and is not removed.  I am under the impression muriatic acid/hydrochloric acid among others, likely at higher concentrations and temperatures,  is the means in which mill scale is removed, commercially and non commercially.  Is this not the method HRPO is achieved?  Thus the question originates as to why the difficulties, or perception of, of removal.   From the other numerous threads this is discussed,  I've not seen an indication that this method should be less than effective.I've been reading on the subject for 2 days,  so it is not a condition of "maybe now you'll be open to answers and suggestions"Last edited by Teggy1; 10-11-2015 at 08:25 PM.
Reply:There must be a bazillion posts on WW related to mill scale removal.  Suggest you use the search function and be prepared to read about a lot of solutions to your problem.
Reply:Flap disc on the grinder. If you let this ruffle your feathers you've got a rough row to hoe here. We have lots of guys w/ lots of knowledge and experience, so just take what you want and ignore what you don't.                               MikeLast edited by mla2ofus; 10-11-2015 at 08:41 PM.Ol' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Why are you wanting to remove the mill scale? What purpose will removing the mill scale do for you?JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Originally Posted by snoeproeWhy are you wanting to remove the mill scale? What purpose will removing the mill scale do for you?
Reply:Get one of those "rub bricks" for concrete work.  Maybe the scratching combined with a bit of muriatic acid will break through the crust and hasten the process. Or a handful of sand and a concrete block."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:Don't dilute the muriatic acid, it's already 70% water....You'll have better luck if you leave the plate out in the sun for a few hours so it warms up, heated acid works much faster. Muriatic acid eats millscale very slowly, you need a small pool of it on the surface, not just enough to barely wet it.Welding/Fab Pics: www.UtahWeld.com
Reply:Originally Posted by MikeGyverDon't dilute the muriatic acid, it's already 70% water....You'll have better luck if you leave the plate out in the sun for a few hours so it warms up, heated acid works much faster. Muriatic acid eats millscale very slowly, you need a small pool of it on the surface, not just enough to barely wet it.
Reply:Originally Posted by MikeGyverDon't dilute the muriatic acid, it's already 70% water....You'll have better luck if you leave the plate out in the sun for a few hours so it warms up, heated acid works much faster. Muriatic acid eats millscale very slowly, you need a small pool of it on the surface, not just enough to barely wet it.
Reply:Originally Posted by In UtopiaX2Since you've already gone this far, use it full strength. While it's on there keep applying and rubbing with an old brush, it'll come off and then the rust starts.
Reply:Originally Posted by OldendumGet one of those "rub bricks" for concrete work.  Maybe the scratching combined with a bit of muriatic acid will break through the crust and hasten the process. Or a handful of sand and a concrete block.
Reply:It will flash rust as soon as you take the metal out of the acid. What are your plans to protect it? Climate controlled shop still has humidity which is moisture.
Reply:I'll use a light coat of wd40 or similar as needed.
Reply:Back to the unanswered question....why remove it at all?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:Originally Posted by storemanBack to the unanswered question....why remove it at all?
Reply:Sounds like a HUGE WASTE OF TIME in my opinion......If that's all I had to do I'd go on vacation....Life's to short for B.S. "science projects".......
Reply:Thanks for the info guys
Reply:If you'd used flap discs it would already be done. I don't really care why you want it off, that's your business.                                               MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:kinda surprised nobody mentioned just a plain hand-held belt sander.
Reply:Originally Posted by Teggy1Was there a point at which I  indicated I was not receptive to suggestions, or indicated feedback was not welcome? I fully understand what mill scale is, how it is produced, why its there, why it is and is not removed.  I am under the impression muriatic acid/hydrochloric acid among others, likely at higher concentrations and temperatures,  is the means in which mill scale is removed, commercially and non commercially.  Is this not the method HRPO is achieved?  Thus the question originates as to why the difficulties, or perception of, of removal.   From the other numerous threads this is discussed,  I've not seen an indication that this method should be less than effective.I've been reading on the subject for 2 days,  so it is not a condition of "maybe now you'll be open to answers and suggestions"
Reply:So Ok, you asked for this, and many others after you will read this where my advise to you and them, like the other's above already stated, stops with, "Hey, it's a welding table. Don't bother to remove the mill scale unless you are into self abuse".Now post pics of your welding table build...Scale or no scale.
Reply:Nah,  you want to see what constitutes getting your panties in a wad, DON'T make a statement on the merits of mill scale removal,  and watch people come out of the woodwork to argue points not made. As it stands, there were pits on the surface of the mill scale, through to the base metal (random in position and size).   I could have left it, but it irritated me.  I could have ground it, and have done so in the past.  It sucks.  So I searched here and elsewhere for ways to remove it, the acid is used somewhat commonly, and seemed a passive method, so I could work on other things,  and for 8 bucks (acid price) how much cheaper do you want?  The original question was why the slow results.  One or two people answered the original question.  Most everyone else chimed in to piss and moan as if I made the statement it was an inferior surface. If asking a question signs my degree in closet chemical engineering, and novice rocket scientist, or trying a different method qualifies as a b.s. lab experiment, I have a hell of a list certifications you can add to my closet educational experience.In the end I guess the posts made are put to life by those interpreting them.   I'm sorry you thought I got my panties in a wad in my initial reply. Just as your posts read condescending and arrogant.Easiest way to remove scale from a welding bench top is to find someone to do it for you. I used a hard grinding wheel on my 7" Bosch grinder nearly flat and the scale flaked off. I followed up with a 7" sander. Then jitterbugged it smooth and oil up. WD40 is great stuff and leaves a nice sheen.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.