Your preferred method of mill scale removal?

[Wamsutta]

I've been using vinegar and it works very well, but I have to first get all the pieces cut small enough to fit into a container. And then I usually have to wait about 4 hours. It would be nice if there was a mechanical way to strip the mill scale off so that I can immediately put the piece to use. The 3M Cubitron II grinding disc works very well, but leaves a slightly rougher finish than I'd like to have. I'm thinking about trying a 3M Clean & Strip disc. I was wondering if anybody has tried one yet for mill scale. From what I understand, they're the bee's knees for stripping paint to bare metal.

 

[PCustoms]

They work great on scale.

 

[BORING HOP YARD]

Sandblasting works great if you have some decent equipment.

 

[Wamsutta]

They work great on scale.

The 3M Clean & Strip disc?

 

[PCustoms]

The 3M Clean & Strip disc?

Yes

 

[strutaeng]

I use the Ziconia flap discs. I buy #40 and #80 discs. I use the #40 for weld blending and heavy rust, and follow up with the #80 and for regular mill scale.

This is on light structural miscellaneous steel shapes like tubes, angles and channels.

 

[tarmy]

This/These

 

[Bert_]

I've never bothered to remove it.

 

[Retroman]

I think I have heard of using Muriatic Acid.
DISCLAIMER: I have no personal knowledge of this method or its safe use.

 

[WAID]

I think I have heard of using Muriatic Acid.
DISCLAIMER: I have no personal knowledge of this method or its safe use.

That would be the standard industrial method. We have a line at work that does it with sheet metal before cold rolling.

 

[NFH2740]

Hydrochloric or phosphoric acid are my preference.

Polyacyrlic discs are far too expensive to use frequently. Flap discs are effective and are less expensive than polyacyrlic, but you risk removing base material.

Both of the former are time consuming.

Circumstance ultimately dictates the best approach.

 

[whateg01]

Are you removing mill scale because you just need a section cleaned to weld? Or are you needing to remove it all so you can do something like paint it?

I have no idea if pferd paid or donated told or if this is fully legit but this video shows silicon carbide coated tooling doing it pretty easily.

 

[jwilson645]

Soak in white vinegar overnight (sometimes longer) and you can wipe it off.

 

[PCustoms]

Soak in white vinegar overnight (sometimes longer) and you can wipe it off.

Do people even bother to read anymore, or do they just type a response and hit post?

 

[whateg01]

Soak in white vinegar overnight (sometimes longer) and you can wipe it off.

Do people even bother to read anymore, or do they just type a response and hit post?

 

[MiteyF]

Flap wheels when you want it to look nice, grinding disc when you want it done fast, sandblaster if you already have a decent sandblaster and aren't in a huge hurry.

 

[scooby074]

Average flap wheels tend to just polish the surface. Clean and Strip style disks wear crazy fast and are expensive.

Ive seen these Walter Mill Scale wheels demoed and they seem to be awesome. Walter makes good stuff if you can find it.

 

[Mr.N]

I've been using vinegar and it works very well, but I have to first get all the pieces cut small enough to fit into a container. And then I usually have to wait about 4 hours. It would be nice if there was a mechanical way to strip the mill scale off so that I can immediately put the piece to use. The 3M Cubitron II grinding disc works very well, but leaves a slightly rougher finish than I'd like to have. I'm thinking about trying a 3M Clean & Strip disc. I was wondering if anybody has tried one yet for mill scale. From what I understand, they're the bee's knees for stripping paint to bare metal.

What about digging a hole in the ground and using plastic sheeting?

Mainly coarse sanding discs and a soft touch.

 

[jwilson645]

Do people even bother to read anymore, or do they just type a response and hit post?

****.........apparently I didn't even read the damn thing.

 

[slodat]

I use the Walter 15L853 Flexcut mill scale discs. They work better than anything else I've tried. I could only find them in a tube of 25, so that's what I bought. I've switched to using cold rolled or HRPO for my sheet metal, so I'm not using them as much as I was when I used hot rolled. Nonetheless, I think they are the way to go. I did buy a really nice Metabo grinder that's dedicated to them. It too was well worth the cost.

 

[MadeByMiller]

I use the Walter 15L853 Flexcut mill scale discs. They work better than anything else I've tried. I could only find them in a tube of 25, so that's what I bought. I've switched to using cold rolled or HRPO for my sheet metal, so I'm not using them as much as I was when I used hot rolled. Nonetheless, I think they are the way to go. I did buy a really nice Metabo grinder that's dedicated to them. It too was well worth the cost.

Fireball Tools has them in 5 packs.

 

[Wamsutta]

Are you removing mill scale because you just need a section cleaned to weld? Or are you needing to remove it all so you can do something like paint it?

I have no idea if pferd paid or donated told or if this is fully legit but this video shows silicon carbide coated tooling doing it pretty easily.

What I'm doing is making T joint test pieces. I cut the steel to 2'' x 8'' strips. The weld seems to start a little bit quicker and run a little bit more constant with the mill scale off; and plus I don't have to see the flakes floating around in the weld pool. I should mention that the mill scale I'm dealing with is a very smooth, grayish blue that looks like anodized coating. It's slick and slippery with no rust whatsoever. The grinding disc will just slide across the top of the steel unless I tip the grinder to an aggressive angle. Flap discs just load up and gloss over. Vinegar melts the stuff right off.

 

[Snip's]

Had a customer that placed an order with me for a couple of corten steel custom pedestals...
He wanted the mill scale removed in order to create the rust patina quickly...
As made in my shop with the mill scale...


I told him we didn't offer the service to remove the mill finish. But suggested he could use a plastic pump sprayer and muriatic acid with proper safety gear. And the acid would remove the scale quickly...

The customer is in the background filling the pump, getting ready to spray my pedestals...


Post application after a couple of hours...

 

[strutaeng]

Cool. I made some cactus yard decorations once from steel scraps and wanted an instant rust. I dissolved salt in warm water and stayed them down and in a few hours, rusty metal!

 

[1320stang]

Needle scaler?

 

[DrReid]

I used Walter Flexcut millscale discs. They eat millscale for lunch. No joke. Can be a little finicky on angle to the metal surface, greatly affecting disc wear pattern and rate. I usually prefer non-woven strip discs, which do not leave little score marks that can result from aggressive application of the Walter discs.