Mill Scale

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Can anybody suggest a good method for removing mill scale? Grinding and sanding don't seem to be the way to go.TIABill
Reply:r u talking about that black stuff.....i've got t know too......because it takes forever to grind off befor i can even paint.I've also been getting these new "off-brand" motorcycle gas tanks to paint.....seems no matter how well i prep them........the paint does'nt like.  I CANT HAVE MY PAINT FALL OFF.!people are telling me it's mexican steel.  WTF.?        thermal arc 252i  -  millermatic 350P -   miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs  -   Hypertherm 1250 G3
Reply:You could always try media blasting.
Reply:Thanks Supe,I'll look into blasting. What I'm doing is inlaying stainless wire into mild hot rolled 1/4" plate. Then grind the stainless bead off flush and letting it reappear after the base metal rusts. I'm using ceramic aluminum oxide sanding disks which can handle the metal ok. It's the mill scale that dulls the disks in a NY second.Unfortunately, my pieces are too large for a cabinet so I'll have to blast them in the open.Thanks Folks.Bill
Reply:Aside from blasting (which is probably the fastest method), flap discs work better than grinding or sanding discs."SOUTHPAW" A wise person learns from another persons mistakes;A smart person learns from their own mistakes;But, a stupid person.............never learns.
Reply:bummer for me though.  I cant Sand Blast Tanks........ Silca sand gets into everything no matter how well u mask ......would destroy Crank Bearings. guess i can  stay with the resin fiber disks.        thermal arc 252i  -  millermatic 350P -   miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs  -   Hypertherm 1250 G3
Reply:flap disks for a grinder.?        thermal arc 252i  -  millermatic 350P -   miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs  -   Hypertherm 1250 G3
Reply:Originally Posted by woi2ldr u talking about that black stuff.....i've got t know too......because it takes forever to grind off befor i can even paint.I've also been getting these new "off-brand" motorcycle gas tanks to paint.....seems no matter how well i prep them........the paint does'nt like.  I CANT HAVE MY PAINT FALL OFF.!people are telling me it's mexican steel.  WTF.?
Reply:Originally Posted by woi2ldflap disks for a grinder.?
Reply:i wuz gonna say, but metarinka is on it..do the budget permit cold rolled?
Reply:Better living through chemistry.  Use acid.  Not you dummy, for the mill scale.  Strong acid, as in 'pickled' as in 'pickled and oiled'.http://en.wikipedia.org/wiki/Pickling_(metal)Standard safety warnings apply.  Also beware of hydrogen embrittlement.And maybe instead of you doing all the removal of the mill scale, just buy/use either P&O or cold rolled to start with.Either that, or media blasting as mentioned.  The best laid schemes ... Gang oft agley ...
Reply:this piece here , the guy handcrafted , and had that black stuff ALL over it....HELL  to get off.....cant remember what he called the metal....asked him not to use it anymorehe said next time he's using pickle.? pickled?  like u said there.but i've gotten tanks too , just recently.........hate'em......a different chopper builder i asked said they're made of  "mexican steel' Attached Images        thermal arc 252i  -  millermatic 350P -   miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs  -   Hypertherm 1250 G3
Reply:I don't know what the black stuff is on your unpainted gas tanks, but if some guy is somehow getting it on there with a torch or something like that, then I doubt it's actual mill scale -- which is a byproduct of the (you guessed it) steel milling process.  But it could mean the same job for you no matter what it is.Beautiful paint, by the way.Moonrise mentions acid.  It's definitely the cost-effective way to go.  If you pay a visit to a plumbing store that supplies actual plumbers, you'll be able to find something like this:It costs less than ten bucks, and it's pure (although not chemical grade) sulfuric acid.  You should learn everything you can about handling the stuff before you open it up -- what safety gear to use, how to dilute it without causing an explosion, how to stop it from eating through everything in its path when you want it to stop, etc.But it works.Jack OlsenMy garage website
Reply:Originally Posted by KZQuixoteWhat I'm doing is inlaying stainless wire into mild hot rolled 1/4" plate. Then grind the stainless bead off flush and letting it reappear after the base metal rusts. I'm using ceramic aluminum oxide sanding disks which can handle the metal ok. It's the mill scale that dulls the disks in a NY second.
Reply:Originally Posted by Jack OlsenI don't know what the black stuff is on your unpainted gas tanks, but if some guy is somehow getting it on there with a torch or something like that, then I doubt it's actual mill scale -- which is a byproduct of the (you guessed it) steel milling process.  But it could mean the same job for you no matter what it is.Beautiful paint, by the way.Moonrise mentions acid.  It's definitely the cost-effective way to go.  If you pay a visit to a plumbing store that supplies actual plumbers, you'll be able to find something like this:It costs less than ten bucks, and it's pure (although not chemical grade) sulfuric acid.  You should learn everything you can about handling the stuff before you open it up -- what safety gear to use, how to dilute it without causing an explosion, how to stop it from eating through everything in its path when you want it to stop, etc.But it works.
Reply:Have lots of ammonia and baking soda on hand.  Wear the chemical grade gloves, have eye protection, and make sure you've got good ventilation.  Once the stuff is out of the bottle, it eats until it's neutralized.Jack OlsenMy garage website
Reply:I'll second or third.....or what ever we're at know ...the acid. I also got a big stone cup I use on small flat pieces. It really rips through the tough stuff.200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:a 3m disc for a grinder works well...use them all the time
Reply:Mill scale is not always a problem, but the oil from P&O is ALWAYS a problem at some point.  You have to get it off before you paint, but too early and you'll get rust. For future reference, here's a steel that removes almost all the mill scale (but not 100%) and actually gives you a better welding surface.check it out:  http://www.scsprocess.com/steelfabri...l-welding.html
Reply:Originally Posted by Grimm1Sounds like you're doing something artistic. I do stuff with bronze kinda like you're describing. But instead of letting the steel rust I hit it with some heat to change the color. Or in the case of bronze on stainless, I change the color of the bronze.