Cleaning Rust of Bandmill Blades

Suggestions for getting light rust off some blades before sharpening. June 30, 2009

Question
Does anyone have a solution that you can dip your blades into for a period of time to take the rust off before sharpening? I have a large amount of blades delivered to me to sharpen and they are pretty well rusted up.

Forum Responses
(Sawing and Drying Forum)
From contributor A:
It sounds to me like whoever is sharpening your blades is doing you a disservice by not protecting your blades when they are sent back to you. I keep my blades inside where it is warm and dry so they are not to rust. This can affect the sharpness of the blades and the performance of the cut. Plus using water for the sawdust is also not recommended. I use straight diesel slowly dripped into a felt that wipes the blade for sawdust buildup. I too used water with additives in the beginning and when things kept freezing up, I switched to straight diesel. 5 gallons lasts about two months of cutting so, I use so little it does not stain the wood being cut.

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From the original questioner:
Actually guess I wasn't too clear. My blades stay nice and clean and out of the weather. I sharpen all my own blades. I got a bunch of LT40 blades used once and tossed, so I want to re-sharpen them to sell but they have some light rust. I was hoping to find a simple way to clean them up. I have about 100 of them and would hate to waste the time of going through them one at a time by hand.

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From contributor A:
You can soak them in vinegar.

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From contributor G:
Oxalic acid dissolves rust. I was going to suggest CLR or Naval Jelly, but that may be expensive for vat use.

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From contributor S:
Get a big old white oak log and put it on your mill, then put a rusty blade on the mill. Run the blade an inch or two into the wood, most of the rust will come right off in about two seconds.

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From contributor R:
For that many blades a light solution of medium acid (muriatic acid (pool acid), phosphoric acid (toilet bowl cleaner/rust remover)); or a heavier solution of a weaker acid like Oxalic in a plastic drum will work. With an acid solution you will need to neutralize the reaction with a base or water and coat with a light oil or a heated base solution (lye -caustic soda) in a plastic or metal drum will work.

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From the original questioner:
that was what I was thinking, even a caustic soda/water mixture was recommended to try as well.

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From contributor W:
Keep in mind that all chemical solutions will turn the steel black. The rust doesn't come off of the steel it just changes chemical make-up. I would clean them with a brass wire brush on a hand held grinder as I sorted them for sharpening, and then run them through that big old white oak log to polish them up nice and shiny.

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From contributor O:
If I had 100 rusty blades I'd try electrolysis to remove the rust. I haven't done this but I know someone who used it to easily restore the top of a rusted Unisaw he found at a garage sale. Basically one makes a solution of an electrolyte, puts the rusty object in it together with another piece of metal like a piece of re-bar, and then hooks up a battery charger one terminal to the rusty object and the other to the rebar. The rust will move off of the rusty object toward the re-bar. Which terminal of the battery charger is hooked to which object matters and I think you would hook the negative terminal to the rusty bandsaw blade. If you get it backwards you'll be moving rust from the rebar "electrode" onto the bandsaw blade so you need to check on this yourself. I understand that an appropriate electrolyte is sodium carbonate (not bicarbonate) which is commonly sold for raising the pH of a hot tub or swimming pool. I've bought it at Walmart for my hot tub.

I have seen cautions about this method affecting the steel of the object, however any effects should only be on the surface of the object so if you don't overdo the rust removal process I would guess it shouldn't hurt a hardened bandsaw blade.