Removing mill scale in cold weather

[restorick]

I've had good results using a white vinegar soak for a day or 2 to remove mill scale from steel tube and flat bar. The problem I have is that my garage shop hovers around freezing most of the winter. The cold inhibits the ability of the acid to do it's work in a timely manner.

Been noodling on ways to warm up the vinegar. Direct immersion with a heating element won't work - I'm sure the acid will eventually compromise the element.

Using a warm water bath should work - I could potentially use a heating element in a laundry sink or larger bin filled with water and then set the plastic bin holding the steel in that bath. Something about that option makes sense but something in the back of my head says there's a better way.

Since I'm in my garage, I don't want to use diluted muriatic acid. I know it would work faster, but I don't want to deal with the fumes and potential for other metal in the shop to be affected.

Appreciate your thoughts on this.
Rick

 

[csp]

How large are the pieces of steel?

These paint removal discs on an angle grinder work really well for removing mill scale. They're far better than a flap disc.

 

[restorick]

How large are the pieces of steel?

These paint removal discs on an angle grinder work really well for removing mill scale. They're far better than a flap disc.

Most of what I'm doing are pieces of square and rectangular tube with flat and plate thrown in for good measure. Most pieces are 3' or less. Plate might be 24x24.

I'm going to try some of those, but I prefer how vinegar works. I'm thinking that a large cooler might help keep the vinegar a little warmer, but I'm also thinking about how I can improve the process even more.

Thanks for the feedback.
Rick

 

[Tinner]

Why do you need to remove the mill scale?

 

[Kaizen]

For the trouble I’d go mechanical unless you have a lot.
Perhaps dumb question but is there any off gassing or whatever where you should not seal it in a cooler?


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[Deadsquiggles]

I use the wheels csp showed above, but I have a bunch of them for my die grinder.

 

[Kenstone1]

a search:
https://www.youtube.com/results?search_query=removing+mill+scale+from+steel+in+cold+weather

 

[king nero]

The discs CSP showed are great, but come at a price. They don't remove any significant amount of metal, so they're very popular in the metal industry for weld prepping on rusted/previously painted parts.

I'd rather use those for the bit of work I have, than messing around with vinegar baths.
If I were to use vinegar baths, I'd use a metal container and a small heater on a propane bottle (they're called "camping gaz" in Europe, just enough to bake an egg, but this should be ideal for your application).

 

[Monza Harry]

The discs CSP showed are great, but come at a price. They don't remove any significant amount of metal, so they're very popular in the metal industry for weld prepping on rusted/previously painted parts.

I'd rather use those for the bit of work I have, than messing around with vinegar baths.
If I were to use vinegar baths, I'd use a metal container and a small heater on a propane bottle (they're called "camping gaz" in Europe, just enough to bake an egg, but this should be ideal for your application).

My thought for adding heat is inline with the "King's" approach I was thinking electric lighting 150, 300, or 500 watt halogen spot light(s) under your bath as required instead of fire but everybody LOVES fire [planned of course]. Add some fiberglass insulation or hard styrofoam for added temp control? Harry

 

[BD1]

I bought this Eastwood contour surfacing tool. I wanted the Metabo but didn't want to spend $800.00 on their Burnishing tool.
I purchased this on sale for $179.00 and it has a three year warranty. With their aggressive 40 grit wheel it does a great job.It's great to clean up welding top too. It's worth it to me because of the non swirl finish from a flapper disc.
I like the finish for my are work being more in a straight pattern.
It's definitely worth it for the money. The soft start and variable speed is great is nice too.

https://www.eastwood.com/eastwood-contour-sct.html

https://www.eastwood.com/eastwood-contour-sctr-abrasive-drum-4-5-inch-40-grit.html

 

[ambenz]

I think if you didn't want to be spendy, a 60W incandescent light bulb inside a large cooler would provide a warm environment to continue to use the process you're comfortable with. My friend keeps his rattle cans in a light bulb heated cabinet , in his garage, over the winter and the bulbs radiant heat keeps his paint from freezing.

 

[Fix Until Broke]

How about an old aquarium and one of the immersion heaters they use in them? The heaters are typically glass so impervious to most chemicals and thermostatically controlled at 60-80F. Keep the gravel on the bottom to protect the glass, glue some foam to the sides/bottom to keep the heat in. Can have a foam lid too.

Could also use an aquarium heater(s) in a cooler or some other insulated container of suitable size?

 

[restorick]

Why do you need to remove the mill scale?

3 primary reasons:

• Welds flow better when it's removed
• The extra layer removed makes it easier to telescope tubes inside of each other
• Looks better (to me at least)

 

[restorick]

I bought this Eastwood contour surfacing tool. I wanted the Metabo but didn't want to spend $800.00 on their Burnishing tool.
I purchased this on sale for $179.00 and it has a three year warranty. With their aggressive 40 grit wheel it does a great job.It's great to clean up welding top too. It's worth it to me because of the non swirl finish from a flapper disc.
I like the finish for my are work being more in a straight pattern.
It's definitely worth it for the money. The soft start and variable speed is great is nice too.

https://www.eastwood.com/eastwood-contour-sct.html

https://www.eastwood.com/eastwood-contour-sctr-abrasive-drum-4-5-inch-40-grit.html

Intriguing. Thanks for the suggestion. Looks like it has other uses outside of stripping body panels. I'll take a peek.

Rick

 

[restorick]

How about an old aquarium and one of the immersion heaters they use in them? The heaters are typically glass so impervious to most chemicals and thermostatically controlled at 60-80F. Keep the gravel on the bottom to protect the glass, glue some foam to the sides/bottom to keep the heat in. Can have a foam lid too.

Could also use an aquarium heater(s) in a cooler or some other insulated container of suitable size?

Thanks. My thought as well. Looking at how I'd set it up. I'm looking at a 150qt. Igloo cooler that could fit the bill.

Whereabouts are you in SE WI? I'm in New Berlin.

Thanks again,
Rick

 

[restorick]

I think if you didn't want to be spendy, a 60W incandescent light bulb inside a large cooler would provide a warm environment to continue to use the process you're comfortable with. My friend keeps his rattle cans in a light bulb heated cabinet , in his garage, over the winter and the bulbs radiant heat keeps his paint from freezing.

I do the same with my rattle cans inside a semi-insulated flammables cabinet. Thanks for the feedback.

Rick

 

[restorick]

I bought this Eastwood contour surfacing tool. I wanted the Metabo but didn't want to spend $800.00 on their Burnishing tool.
I purchased this on sale for $179.00 and it has a three year warranty. With their aggressive 40 grit wheel it does a great job.It's great to clean up welding top too. It's worth it to me because of the non swirl finish from a flapper disc.
I like the finish for my are work being more in a straight pattern.
It's definitely worth it for the money. The soft start and variable speed is great is nice too.

https://www.eastwood.com/eastwood-contour-sct.html

https://www.eastwood.com/eastwood-contour-sctr-abrasive-drum-4-5-inch-40-grit.html

Curious - the drums are a bit spendy. How long do the drums last?

 

[BD1]

Intriguing. Thanks for the suggestion. Looks like it has other uses outside of stripping body panels. I'll take a peek.

Rick

I bought it specifically for metal work.
It is great for a easy quick clean up of welding tables.
I like the straight pattern marks instead of swirls from a 4 and 12/" grinder disc.
I'm gonna build some rocket stoves using 4" tube. It'll be perfect for that.


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[BD1]

Curious - the drums are a bit spendy. How long do the drums last?

I bought the tool and a variety of drums on sale. I haven't used it enough to comment on longevity.
I'm sure it'll be similar to a flapper wheel for a die grinder, except these are 1" and 4" wide.
Surface conditions will definitely impact how long it lasts.


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[restorick]

I bought the tool and a variety of drums on sale. I haven't used it enough to comment on longevity.
I'm sure it'll be similar to a flapper wheel for a die grinder, except these are 1" and 4" wide.
Surface conditions will definitely impact how long it lasts.


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Thanks. Definitely interested - there are other things I can use it for. I'll still use vinegar for mill scale tho - not a fan of that stuff getting all over the garage, and soaking my metal is therapeutic... ;-)

Rick

 

[Fix Until Broke]

Another idea might be to use one of the thin battery heaters under the container.

Insulation of the container on all sides is the most important thing to keeping the solution warm.

 

[BD1]

Thanks. Definitely interested - there are other things I can use it for. I'll still use vinegar for mill scale tho - not a fan of that stuff getting all over the garage, and soaking my metal is therapeutic... ;-)

Rick

I work with recycled horseshoes for my artwork. They are usually rusty and ugly.
I soak them in basic white vinegar for a couple days and works well.
Have you tried citric acid ?? I have read it works well.

https://www.hawk-hill.com/removing-rust-no-scrubbing/


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[restorick]

I work with recycled horseshoes for my artwork. They are usually rusty and ugly.
I soak them in basic white vinegar for a couple days and works well.
Have you tried citric acid ?? I have read it works well.

https://www.hawk-hill.com/removing-rust-no-scrubbing/


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I've heard of citric working for rust, wasn't so clear on how it works for mill scale removal. Guess it's cheap enough to give her a go...

 

[restorick]

Another idea might be to use one of the thin battery heaters under the container.

Insulation of the container on all sides is the most important thing to keeping the solution warm.

Interesting thought. I'll check it out. Thanks!

 

[JackOfDiamonds]

I use Citric acid a lot (around 10% concentration) to pickle brazed cromoly bike frames. It works a lot faster when warm. It removes the brazing flux and most of the black scale from the brazing process, but if you leave it in a long time, it turns the tubes black again with a uniform thin layer of oxide. It won't result in bare metal, it's actually re-pickling the steel. I like what this is doing to the inside of the tubes because I believed the pickled surface will be more corrosion-resistant than bare metal. The new black surface looks really nice actually but I'm not totally sure if I need to be sanding it back down to bare metal before painting or if I can paint right over the new pickled surface.

 

[03roadking]

This tool is on clearance at Lowes right now for $45.
I have found it to do a really good job and cleaning steel down to shiny metal.
I made my own cable railing for my deck out of 2x2 tube and had a lot to clean up before taking to the powder coater. This thing worked awsome!
I wanted a solution where I didnt need to use liquids.

Take a look at how it does!

 

[mikegt4]

This tool is on clearance at Lowes right now for $45.
I have found it to do a really good job and cleaning steel down to shiny metal.
I made my own cable railing for my deck out of 2x2 tube and had a lot to clean up before taking to the powder coater. This thing worked awsome!
I wanted a solution where I didnt need to use liquids.

Take a look at how it does!

Looked this up on Lowes website and found 2 at a store 20 miles away for $39.95. I spent 20 minutes looking for them ( what few employees there were busy helping people find items), I did find one under a shelf.

I got it home and found that it didn't include the wheel in the video only one sanding drum of oddball prepriatory dimensions. The desired wheel is available on Amazon for $20 each. Just a warning of the real cost to remove mill scale with this tool. If it works like the video then it may be worth it.

 

[Kaizen]

Looked this up on Lowes website and found 2 at a store 20 miles away for $39.95. I spent 20 minutes looking for them ( what few employees there were busy helping people find items), I did find one under a shelf.

I got it home and found that it didn't include the wheel in the video only one sanding drum of oddball prepriatory dimensions. The desired wheel is available on Amazon for $20 each. Just a warning of the real cost to remove mill scale with this tool. If it works like the video then it may be worth it.

I bought the Eastwood machine a few months ago for auto body work. The cost of the drums is ridiculous as you found out. I presently only use it for certain tasks as the cost makes me frugal. Like my nice welding helmet vs my old beat up one.


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[mikegt4]

Update:
I have been looking around for the best source for the rust/paint removal drums, most places have them for about $20-25 plus shipping but few places actually have them in stock. I found that the company that actually makes the tool for Craftsman, Porter Cable and Black & Decker is Wellington Corp. near Cleveland, Ohio. Their prices are the same as other sources but they offer a lot more types of sleeves and some package deals and all with free shipping in the US. They also have some items on sale.

https://www.restorertools.com/