derusting rasps, taps and dies

[DaveLeard]

There has been so much written about removing rust I'm reluctant to search the archives and, at risk of being called a troll, just explain my situation in a new post. I want to derust a coarse American pattern rasp, some taps and a die. My derusting experience has been with citric acid and electrolysis. I feel almost certain citric acid would degrade the edges of the aforementioned tools, and wonder if electrolysis, or possibly molasses, would be a safer bet. I've always avoided Evaporust because of expense and don't have any idea what it would do to a sharp cutting edge.

I know acid treatment is actually used to sharpen metalworking files, but haven't seen any recommendations regarding rasps, taps and dies.

If anybody has a successful experience derusting items like those mentioned or can direct me to a relevant thread in the archives, please advise.

[Tapper]

I use Evaporust; Harbor Freight has the best price in my area. You might think about also posting over at OWWM.org in the Metalworking section. Lots of guys over there deal in old iron.

Doug

[bandit571]

All of mine seem to get....either a brass wire wheel ( OD..and files) or a Rifle Bore cleaning brush, chucked in a drill, ID.  

KISS.

[AHill]

Pretty much anything acidic will work to de-rust, but understand that the chemistry behind it is to remove good metal underneath the rust. So, overexposure in an acid bath (vinegar, muriatic acid, citric acid, etc.) risks rounding off sharp edges in any cutting tool or causing pitting in the base metal. Start with a brass wire wheel and remove as much rust as possible before proceeding to an acid soak. I wouldn't soak longer than a couple of hours at the start. Better to err on the "needs-more-time" side than the "I've-gone-too-far" side.

Evapo-Rust uses chelation as the chemical process. Chelation actually eats away at the actual rust, leaving the good metal substrate intact. There's no danger in chelation removing more metal due to longer exposure. it does impart a dark gray color to the metal - which can be removed with a light scrub.

My personal preference is Evapo-Rust.

[Scott W]

I used vinegar on a bunch of old files and it did nicely   FWIW

[pprobus]

Evaporust, like many of the others have said.  There's a quicker equivalent, that I believe is also cheaper, Youtube channel "Project Farm" found when testing de-rusting agents. Not trying to shill for the channel, I just like watching his videos and testing methods seem to be mostly sound, and in the interest of full disclosure, I am neither a subscriber to his channel, nor a contributor, I just watch him on a regular basis (which probably bumps up his stats and increases his ad revenue a bit).

I, personally, have been using Evaporust for a while and like it.  I have left parts in for over a week with no damage other than what was caused by the rust.  Keep in mind, Evaporust removes the rust, it does not "convert" it back to good metal, so you will have pitting if the parts have been rusting for a while. I have also not found it to be very "paint safe".  I.e. just about everything I put into ER that still has paint on it, the paint gets soft and loose, although it is NOT a paint remover except in small patches.  I know that may sound contradictory, but I have had small paint areas just fall way but other areas get soft, but still took some work to fully remove, unlike paint removers I have used, but even after the paint has re-dried after being immersed in ER, its easier to remove when comparing to other parts, from the same machine, with the same paint on it that did not go into the ER.  Not an issue for what you're doing, but something to keep in mind for later.  Don't forget, ER (or its competitor's equivalent products) is expensive, but its also re-useable.  I don't worry about mixing new and old (I don't have any "new" anymore at this point anyway), just keeping the containers sealed to minimize evaporation losses (since its water based, you can add water to ER if you see some of it has evaporated while in storage, the active ingredients are left behind, only the water evaporates off).

I think you'll be fine with the rasp, the issue may be the taps and die.  Depending on how badly rusted they are, they may be too dull to be useful anymore. Dull taps are prone to breaking, leaving you with a potential huge headache in trying to remove it. Not sure about dies, but taps can be sharpened, but what it costs if you were to take it to a professional, I have no idea and if its even worth it. If you know a hobbiest metalworker with a TCG, perhaps they can sharpen them for a reasonable fee. Then keep that person in mind for when you need router bits sharpened.

[DaveLeard]

I appreciate everyone's replies. I'm reevaluating my reluctance to purchase Evaporust, and starting to think of a couple of people from whom I might borrow some.

I'm also leaning toward mechanical cleaning with a brass brush. Over the years, I've seen a lot of good results from brass brushes and steel scrapers, although scraping is  impractical on this project. There would still be the option to follow with a chemical clean afterwards.

[Cliff Ober]

I appreciate everyone's replies. I'm reevaluating my reluctance to purchase Evaporust, and starting to think of a couple of people from whom I might borrow some.

I'm also leaning toward mechanical cleaning with a brass brush. Over the years, I've seen a lot of good results from brass brushes and steel scrapers, although scraping is  impractical on this project. There would still be the option to follow with a chemical clean afterwards.

I too use Evaporust for just about everything that needs it. On the brass brushes, be aware that a *lot* of those out there are really just brass plated steel wire. When you purchase, take a magnet along to test. I use  a handled brass brush for cleaning files; it also helps clean the gray off of Evaporusted items, but will leave a brass sheen to the steel. It also leaves the brass sheen on files when they've been cleaned, but there's no harm to it.