Alkaline Rust Remover Formulas and Q&A's

A. We once used to use an alkaline product called Oakite. I'm sorry I don't remember the source.

Thanks, Sandro. Oakite is the name of a division of Chemetall. Thanks.
But it sounded to me like Mr. Milan is looking for a generic formula.

from The Chemical Formulary, c. 1940,
alkaline-acid pickling of Inconel, (I don't know if it was ever meant for steel) this Kickapoo juice is hotter than a pistol, and just as dangerous. I don't recommend anyone using it, for reference only.

steel tank, 180 °F
NaOH - 18 ounces
sodium carbonate ⇦this on eBay or Amazon] - 18 ounces
KMnO4 - 7 - 11 ounces
Water 1 gallon

acid pickling solution
wooden tank (I'm not kidding, this is OLD) 180 °F
66 degree baumé H2SO4 16 ounces
Sodium Nitrate 8 ounces
copper sulphate ⇦this on eBay or Amazon [affil links] or copper nitrate ⇦this on eBay or Amazon [affil links] 1.5 ounces water 1 gallon.

It's these kinds of solutions which make me glad that there are now proprietary solutions around.

There are two ways you can go. One is to buy a proprietary compound from a specialty chemical supplier. You will pay more but you will get technical support and laboratory backup.

If you want to make your own product, you can mix sodium hydroxide (or potassium for better rinsing or a combination) along with a couple percent of EDTA chelant (or Sodium Gluconate). You want to use the product hot 160+ at anywhere between 8- 16 oz gallon.

Considering the complexity of a really good rust remover, why not go with a commercially prepared product. The main components are going to be lye and sodium glutamate. Numerous other materials tailor it to your need and water.

Generic formulas can be found in the AMS book on cleaning.

My advice to you is not to try a generic formula, it is the small additives that suppliers add which makes all the difference. Go to a supplier!

You have to really careful with chelants because they prevent your water treatment system from removing some metal ions.

A. For a summary of all the former answers you can use an exact formula from the military specification MIL-C-14460 is the mil you need and you will have all the answers you need . (Use the non cyanide version)

A. Try a solution of about 10% by wt. sodium hydroxide and 2 to 5% triethanolamine. Soak article in heated solution a few minutes for light rust. Rinse with passivating solution to prevent flash rust.

A. Hi Nina,

Without knowing your customer's requirements, the parameters under which this rust removal is being performed, the amount of rust that needs to be removed, and the customer's limitations in terms of equipment, it is difficult to formulate from a distance.

A first glance at your formulation, however, leads me to believe that you have too little caustic present. The choice of surfactants in the product is somewhat curious to me, but low foamers from the Triton DF series are a good place to start. Obviously, an alkaline de-rusting product doesn't need much surfactant to begin with; I'm not sure that I would put any in it at all.

Good luck!

To Ted: I wouldn't be too concerned about any proprietary information being revealed in Nina's formulation. Most alkaline de-rusting products are pretty much created equal.

A. Although I am not familiar with the Triton detergent you listed, I think it may be similar to BG-10 which may be more stable in very strong alkaline solutions over time and elevated temps. I am guessing that the Dowfax is helping mostly to keep the nonionic surfactant in solution. I have worked with DF-16 and it is a good wetter and has low foam below its cloud point of about 100 deg F. but if you add solubilizers I think you would still get foam. Perhaps you could leave out the nonionic surfactants and just keep the Dowfax since it does have some wetting ability.

A. Hi Riccardo. We added your question to a thread which explains that the NaOH is not the heart of what removes the rust. Chelators and proprietaries are important that job. Please take the time to introduce your situation, which both increases the interest level and will help steer the responses towards being most directly useful to you. Thanks.

Luck & Regards,

A. Hi again. I am not a chemist but "alcohol ethoxylate" appears to be a surfactant which helps remove oil, possibly among other jobs; hexyl D-glucoside appears to be a detergent/surfactant.

I am not seeing anything to specifically 'dissolve' rust since I'm not seeing chelates, but high pH will discourage further rusting. Heavy rust is often 'dusty', 'fluffy', hygroscopic, and poorly adherent. So it seems that the proper surfactants/detergents, plus heat (maybe boiling), plus perhaps some mechanical abrasion, might well remove most of the rust.

Luck & Regards,

Hi Ted,

thanks. It is probably as you suggest. Probably temperature and agitation are doing most of the job.
Thanks