Ridiculous myth was true!

[Batmanacw]

This file had shiny flats on the tips of the teeth in several spots. It was pretty dirty but most of all it just skated over mild steel on both sides. I quit using it years ago because it wouldn't cut clean or dirty. It turned into my beater file.



I soaked it in plain white vinegar for a week. Then scrub and rinse.





It is obvious that acid etching will not restore damaged or missing teeth.

The flat edge of the file had badly damaged teeth and vinegar did not restore those to cutting condition. I ground that edge smooth so I'd have a nice safe edge in place of the worn teeth.

The other edge is a radius. The first 1.5" was damaged and vinegar did not fix that issue. The rest of the length cuts great.

The vinegar did a fantastic job of removing the shiny edges on the teeth. The file cuts like new, possibly better. The finish off the file looks very good. I have hung this file up to use on my lathe because of the 50⁰ angled fine teeth with the safe edge it now wears.

If anyone had told me a week ago that this file was salvageable I'd have laughed....

I put several other slightly dull files with intact teeth in vinegar for 24 hours and saw noticeable improvement. One was an AM Swiss #0 cut pillar file that I really like but required pressure to get it to cut. Immediate improvement.

Call bs all you want. I barely believed it myself until I saw improvement in 4 different files. White vinegar is a very useful tool to keep around.

 

[woodchucker]

a week in vinegar is way too long. Two things happen, pitting, hydrogen embrittlement.
The pitting will ruin the teeth. the HE will make the file week. a few hours would have probably worked.
it doesn't take long to have any acid work.

edit: it doesn't look like you have any damage from pitting.. so I guess you got lucky. It can happen.. Those pics look good (I don't know why)

 

[Batmanacw]

a week in vinegar is way too long. Two things happen, pitting, hydrogen embrittlement.
The pitting will ruin the teeth. the HE will make the file week. a few hours would have probably worked.
it doesn't take long to have any acid work.

You can see the pictures. I couldn't help the week. I had to fly to Illinois and I knew it needed a lot of help. I'm sure its ruined because it cuts so nicely. Lol. It was garbage. Now it's a weak sharp fiile.

 

[Batmanacw]

a week in vinegar is way too long. Two things happen, pitting, hydrogen embrittlement.
The pitting will ruin the teeth. the HE will make the file week. a few hours would have probably worked.
it doesn't take long to have any acid work.

edit: it doesn't look like you have any damage from pitting.. so I guess you got lucky. It can happen.. Those pics look good (I don't know why)

Maybe all the crud protected it?

My other files I only did 24 hours.

 

[RJSakowski]

I sharpened a large batch of old dull files by acid etching with muriatic acid. I have had no issues with weakened files.

File Management

I had a bucket of old files that had been sitting my barn for the past thirty years. As I recall, they were purchased at an auction of a blacksmith shop. They were well used at the time and had accumulated a generous coating of rust after a more than a quarter century of exposure to the...

www.hobby-machinist.com

 

[woodchucker]

I sharpened a large batch of old dull files by acid etching with muriatic acid. I have had no issues with weakened files.

File Management

I had a bucket of old files that had been sitting my barn for the past thirty years. As I recall, they were purchased at an auction of a blacksmith shop. They were well used at the time and had accumulated a generous coating of rust after a more than a quarter century of exposure to the...

www.hobby-machinist.com

I didn't say it doesn't work, I believe 1 week is way long. You don't state how long you left yours in the acid.
I have used the method, but not for long. I have seen the damage vinegar does when left too long.

 

[Batmanacw]

I didn't say it doesn't work, I believe 1 week is way long. You don't state how long you left yours in the acid.
I have used the method, but not for long. I have seen the damage vinegar does when left too long.

Vinegar pits the crap out of axe heads. I never do more than 12 hours pulling it to wire brush scrub every couple hours.

 

[ltlvt]

I will try that i have a couple i have had for 50 years. I'm guessing it will clean any aluminum in the teeth.

 

[RJSakowski]

I didn't say it doesn't work, I believe 1 week is way long. You don't state how long you left yours in the acid.
I have used the method, but not for long. I have seen the damage vinegar does when left too long.

I etched for about two days but muriatic acid is a much stronger acid than vinegar. Vinegar is typically about 5% acetic acid (.8 molar)while the muriatic acid I use is 32% (9 molar) or more than 10 times the strength.

 

[Parlo]

Is it safe to use white vinegar in an ultrasonic cleaner?