Acid vat

[Frank S]

Removing mill scale and surface rust from steel is a laboriously labor consuming process.
you can grind it sand it, wire brush it and sometimes need to do all of the above, or you can sand blast it but there is the labor and time element again. But a product I use often called rust blast has the highest concentration of phosphoric acid allowed by law it literally eats rust and given time will soften mill scale to the point it can be wiped and rinsed away.
But the process takes time as does everything else since you have to keep the metal wet with the acid for a period of time.
A better way to clean rust from small parts like nuts and bolts is to immerse them, then leave them over night or longer.
I have a some long formed and fabricated parts I want to clean. If I can dunk and forget them for a day or so while doing other things, I am removing much of the labor part hopefully. the acid will not react with steel but will cause galvanneal to boil off all of the coating will etch aluminum and eventually erode it away.
here is the vat I made for this process I will know next week after the 55-gallon drum of the acid arrives how well it will work if for nothing else I still have a nice dipping tank.
Made from a full 4x8ft sheet of 14ga Much deeper than I need but better to be too deep than not deep enough.

trough formed in for draining.

source of sq tubing for legs and rim the round part I straightened out to a larger radius to make trusses for my green house.

finished vat just needs painting but that will wait.

The brass valve may be a problem might have to replace with one made of stainless

[DIYer]

Thanks Frank S! We've added your Acid Vat to our Miscellaneous category,
as well as to your builder page: Frank S's Homemade Tools. Your receipt:

Acid Vat by Frank S

tags: metalworking

[trevor_60_r]

Hi Frank,

Looks like it should work well.
I will be interested to see how well this goes.

I have done some experiments with different acids myself in a plastic 205 liter drum with the top cut out, and suspending parts by stainless steel hooks hung from the sides of the drum with some good results. Look forward to your findings.

Thanks Trevor

[Frank S]

I have a few more sheets of 14ga I have been needing a good long parts cleaning vat for when I make or rebuild hydraulic cylinders. I may make one 24 inches wide and 12 inches deep with a large holding tank and pressure pump mounted under it. I normally use a non-petroleum water soluble solvent that when used with hot water really eats through caked on grease build up. A cleaning vat of that size would really be an asset when I do mechanic work as well.

[Frank S]

the acid arrived and the parts are in the vat I covered the vat with a makeshift top using a roll of rubber and a piece of plywood this is to contain any fumes and slow evaporation.

It always seems that no matter the situation I most always have something in my storage bins to cover what needs to be done. in this case the roll of 3/32" thick rubber that I have had for at least 25 years

[drivermark]

I've used plain ol' white distilled vinegar for removing mill scale just got to make sure you soak parts in acetone or lacquer thinner first to remove the oils
(will help the vinegar last longer) it takes a few days but the mill scale will mostly just wipe right off.

[trevor_60_r]

Thanks for your input Drivermark, '
I will post some info on my acid bath and the procedure that works best for me a bit later on. (Just got out of hospital after a operation, so won't be for a week or two.)

[choochoo1979]

You can buy Phosphoric Acid in most farm supply stores, as it's used inn high strength for cleaning milking operations.

FYI,
Scott

[drivermark]

I like the vinegar method because it's readily available, and not as hazardous to deal with as stronger acids. I strain the vinegar when it's used up and spread it along any places I don't want grass to grow. (gravel driveway, fence lines etc)

[Bony]

Agreed, white vinegar is extremely effective, very inexpensive, not as corrosive as acid and non hazardous. It's also excellent at removing mill scale, just washes off after a few days soaking.