Hand Files and Vinegar Question

[Modern Garage]

I just cleaned up a couple of garage sale files by soaking about 24 hours in common vinegar from my kitchen and, having never tried this before, I'm astounded at how well it worked. My question is why? I understand the mild acid in the vinegar etches away corrosion but what stops it from eating away the sharp edges at the tops of the teeth and thus dulling the file? Or is the rehabbing factor simply that it cleans the debris stuck in the teeth of the file and doesn't actually affect the original file much at all (beyond enough to gray the steel slightly)? Does the acetic acid of the vinegar only dissolve a few molecules deep on the file - not enough to make it seem 'dull'?
I'm no chemist - I use hand tools, for pete's sake - can anyone enlighten me?
Is this one of those un-answerable quandaries like, what is my wife actually thinking when she changes clothes four times a day...
Joe

 

[Roberts210]

Try the files out and see if the sharp edges keep their sharpness.

 

[slowtwitch73]

USB microscope before and after. Report back.

 

[rockettauto]

Acid can sharpen them but at some point can dull them as well.

Think of the chemical sharpeners for tungsten rod. Done at the right interval the tip is sharpened, done too long and the sharp point is completely eroded to a rounded point.

Basically at first it will thin the cutting edge and make it sharp and then it will round it since it attacks the part that sticks out faster than the rest.

 

[RTM]

I go here for file sharpening

Boggs Tool & File Sharpening Company

14100 Orange Ave, Paramount, CA 90723 [email protected] (800) 547-5244

boggstool.com

 

[d42jeep]

I’ve had decent luck cleaning rusty files in evaporust.
-Don

 

[four.cycle]

I put all my old files on Craigslist in a "FREE" ad: "Knifemaker's Special!" - they were all gone in less than an hour!
just order new ones from Cripe Distributing. Go to their website and get the "secret code" to get the discount and NO TAX. (don't order through ebay!) - you can thank me later.

** as with Harry Epstein, you have to pay freight when you're dealing with Cripe, so buy lots of stuff all at once to save any money.

 

[Provincial]

The old-time recommendation to sharpen dull files was to soak them in dilute sulfuric acid. Standard automotive batteries use sulfuric acid, so it was/is readily available. I've seen a recommendation to use 9 parts water to 1 part sulfuric acid for this purpose.

 

[Modern Garage]

I

Try the files out and see if the sharp edges keep their sharpness.

USB microscope before and after. Report back.

I don't think I've ever worn out a file in my life. Clogged quite a few and seen plenty too rusty to use and too chipped from harsh storage, but never just flat worn out, so I don't think an empirical test of lifespan will be feasible - for me anyway. As to microscopic inspection, I haven't peered thru a microscope since high school. Aproximating a half thou on my dial indicator is as small as I go anymore.

Acid can sharpen them but at some point can dull them as well.

Think of the chemical sharpeners for tungsten rod. Done at the right interval the tip is sharpened, done too long and the sharp point is completely eroded to a rounded point.

Basically at first it will thin the cutting edge and make it sharp and then it will round it since it attacks the part that sticks out faster than the rest.

Exactly my thoughts on the vinegar process.
I've never heard of 'chemical sharpeners for tungsten rod'. What application uses this procedure?

The old-time recommendation to sharpen dull files was to soak them in dilute sulfuric acid. Standard automotive batteries use sulfuric acid, so it was/is readily available. I've seen a recommendation to use 9 parts water to 1 part sulfuric acid for this purpose.

So with a little research the relative acidity of household vinegar vs diluted 9:1 battery acid could be compared but I'm going to guess it's close enough for today's discussion and move on.

Barring further input the current theory seems to be: weak acid scrubs away the surface debris and some corrosion but isn't aggressive enough to wipe off the sharp edges in a short (overnight) time frame. So it doesn't restore or "sharpen" a file but simply cleans it enough to make it useful again after some time of neglect or correct but intensive use. Repeated acid (vinegar) treatment would likely have the deletious effect of wearing away the sharp cutting edges but it seems that's a long ways away.
Make sense?

I'm sure I'm spending way too much time thinking about this since there are probably only an handful of us left who even bother to pick up a file...
Joe

 

[Mintgrun]

I've used electrolysis to clean files. The solution is soda and water, so it is the opposite of an acid bath. Rust fizzes away and it loosens the debris stuck in the teeth.

I'm using a little two-amp battery charger and it works just fine. (I made the mistake of connecting two battery chargers at the same time and suddenly neither of them worked anymore).

I use the same process to clean circular saw blades. It only takes a few minutes in the bucket to loosen the pitch/gunk that sticks behind the carbide teeth and it washes right off in the sink. It's easier than messing with chemicals.


I will say that after using the same solution for years, I consider it hazardous waste, even though it was only soda and water to begin with. It must be saturated with heavy metals by now.

 

[rockettauto]

I


I don't think I've ever worn out a file in my life. Clogged quite a few and seen plenty too rusty to use and too chipped from harsh storage, but never just flat worn out, so I don't think an empirical test of lifespan will be feasible - for me anyway. As to microscopic inspection, I haven't peered thru a microscope since high school. Aproximating a half thou on my dial indicator is as small as I go anymore.


Exactly my thoughts on the vinegar process.
I've never heard of 'chemical sharpeners for tungsten rod'. What application uses this procedure?


So with a little research the relative acidity of household vinegar vs diluted 9:1 battery acid could be compared but I'm going to guess it's close enough for today's discussion and move on.

Barring further input the current theory seems to be: weak acid scrubs away the surface debris and some corrosion but isn't aggressive enough to wipe off the sharp edges in a short (overnight) time frame. So it doesn't restore or "sharpen" a file but simply cleans it enough to make it useful again after some time of neglect or correct but intensive use. Repeated acid (vinegar) treatment would likely have the deletious effect of wearing away the sharp cutting edges but it seems that's a long ways away.
Make sense?

I'm sure I'm spending way too much time thinking about this since there are probably only an handful of us left who even bother to pick up a file...
Joe

Tig welding. In lieu of grinding you can use a corrosive sharpening compound.

A few successive dips it comes out sharp. Dunk It and leave it there , it'll come out dull as hell.

I've seen it suggested to dip the file, wipe the surface and let it sit like that. Then the acid just hangs out in the pits.....but idk how effective it is.

 

[Modern Garage]

Tig welding. In lieu of grinding you can use a corrosive sharpening compound.

A few successive dips it comes out sharp. Dunk It and leave it there , it'll come out dull as hell.

Huh, didn't know that, I just grind 'em. Learn something new every day - guess I can take the rest of the day off.
Joe

 

[Mintgrun]

I just grind 'em

I like to use one of these to spin them when I grind them.



While holding my breath to avoid the thoriated dust.

 

[slowtwitch73]

'Worn out' is arbitrary. Even a beat to hell crapped out file will do work.... just at what rate and with how much input?

If you buy two of the same files and use one a good bit, then grab the unused one, you'll notice a big difference.

A USB 'microscope' is handheld, cheap, shows up on your 'puter screen.... not nearly microscopic but would be interesting to see the file teeth before and after.

 

[matthew]

The old-time recommendation to sharpen dull files was to soak them in dilute sulfuric acid. Standard automotive batteries use sulfuric acid, so it was/is readily available. I've seen a recommendation to use 9 parts water to 1 part sulfuric acid for this purpose.

If I remember correctly, dilute sulphuric acid actually corrodes steel more quickly than highly concentrated. I don’t know what pH the peak corrosion rate would be at, but as counterintuitive as that seems the dilution may have been to speed up the process, not to keep it moderated.

 

[Cleave]

I go here for file sharpening

Boggs Tool & File Sharpening Company

14100 Orange Ave, Paramount, CA 90723 [email protected] (800) 547-5244

boggstool.com

Great tip - I'll have to try them sometime.
There are many times where the file is superior to the angle or bench grinder - hard to get something really flat with a round grinding wheel, also the heat factor, and getting in funny places.