All About Pocket Knives

OK fellas, apparently the go to for removing rust from virtually everything is to soak them in either vinegar or store bought liquid rust removers like evapo-rust, etc. While this method may be fine for certain items I DO NOT recommend it be used on folding knives. I have received 6 knives in the past 2 months that have suffered from this treatment. All of the owners mentioned seeing a YouTube video on knife restoration using this method (I did a quick search, and there is more than 1 ). In my very early days I tried using vinegar soaks on straight razor blades, the results were catastrophic. It somehow (I'm not chemist so I can't explain the HOW) stresses tool steels to the point of fracturing, 9 out of the 10 blades I had in the vinegar soak cracked. That being said I no longer use vinegar soaks on thin steel or for pocket knives in general. Now granted, in moderation it may be o.k I'm not sure how long this you-tuber recommended folks soak their knives in vinegar or if the owners adhered to these instructions or not. The bottom line is I have had these 6 knives come to me in the same condition from all over the country. They all feature broken backsprings (12 backsprings and counting) and I'm assuming the knives were not given a baking soda water rinse to neutralize the acids because they all come to me more rusted than they were before the owner attempted their "restoration".

This is a fine example of someone with limited knowledge publishing instructional videos that may or may not contain all of the information necessary to effect the desired result.

In my opinion, vinegar soaks are not for the purpose of "restoring" pocket knives.

I have in the past used 50/50 water vinegar soaks to remove rust from axe heads, steel traps, tools etc with little to no ill effect. I believe the hardness and thinness of the steel item being soaked has a great affect on the end result, not to mention the concentration of the liquid rust remover being used.

Thanks or some great advice ____Monk

OK... just for my information... What is wrong with using Evapo-Rust?
I use E.R. for things other than pocket knives because it doesn't effect the rubber or plastic parts..... But, are you saying it will weaken a spring?

OR, is this effect just from vinegar?

Thanks for the heads up!

Meridian_Mike wrote:OK... just for my information... What is wrong with using Evapo-Rust?
I use E.R. for things other than pocket knives because it doesn't effect the rubber or plastic parts..... But, are you saying it will weaken a spring?

OR, is this effect just from vinegar?

He didnt use a name brand but described it as a water based rust remover, evapo rust seems like the most popular. I'm not saying it can weaken springs. I'm saying I have 12 BROKEN backsprings here from people soaking their knives in "rust removers"

muskrat man wrote: He didnt use a name brand but described it as a water based rust remover, evapo rust seems like the most popular. I'm not saying it can weaken springs. I'm saying I have 12 BROKEN backsprings here from people soaking their knives in "rust removers"

10-4

muskrat man wrote:OK fellas, apparently the go to for removing rust from virtually everything is to soak them in either vinegar or store bought liquid rust removers like evapo-rust, etc. While this method may be fine for certain items I DO NOT recommend it be used on folding knives. I have received 6 knives in the past 2 months that have suffered from this treatment. All of the owners mentioned seeing a YouTube video on knife restoration using this method (I did a quick search, and there is more than 1 ). In my very early days I tried using vinegar soaks on straight razor blades, the results were catastrophic. It somehow (I'm not chemist so I can't explain the HOW) stresses tool steels to the point of fracturing, 9 out of the 10 blades I had in the vinegar soak cracked. That being said I no longer use vinegar soaks on thin steel or for pocket knives in general. Now granted, in moderation it may be o.k I'm not sure how long this you-tuber recommended folks soak their knives in vinegar or if the owners adhered to these instructions or not. The bottom line is I have had these 6 knives come to me in the same condition from all over the country. They all feature broken backsprings (12 backsprings and counting) and I'm assuming the knives were not given a baking soda water rinse to neutralize the acids because they all come to me more rusted than they were before the owner attempted their "restoration".

This is a fine example of someone with limited knowledge publishing instructional videos that may or may not contain all of the information necessary to effect the desired result.

In my opinion, vinegar soaks are not for the purpose of "restoring" pocket knives.

I have in the past used 50/50 water vinegar soaks to remove rust from axe heads, steel traps, tools etc with little to no ill effect. I believe the hardness and thinness of the steel item being soaked has a great affect on the end result, not to mention the concentration of the liquid rust remover being used.

MM, I can tell you a little bit about why this would be damaging to a pocket knife. You are putting an acid in contact with two different metals, brass and stainless steel and a third nickel silver. It doesn’t take a chemist to recognize that you just created a battery. That reaction is breaking down the metal in the two dissimilar metals. Anytime you use something acidic on two metals your going to get this reaction. Being a chemical reaction it happens quickly and does more damage than you would think in a short time.
SSk

Sharpnshinyknives wrote: MM, I can tell you a little bit about why this would be damaging to a pocket knife. You are putting an acid in contact with two different metals, brass and stainless steel and a third nickel silver. It doesn’t take a chemist to recognize that you just created a battery. That reaction is breaking down the metal in the two dissimilar metals. Anytime you use something acidic on two metals your going to get this reaction. Being a chemical reaction it happens quickly and does more damage than you would think in a short time.
SSk

Yep, that is why I was wondering about Evapo-rust....

From the ER web site....
"Best of all, Evapo-Rust® is safe to use: non-toxic, non-corrosive, and contains no acids, bases, or petroleum solvents."

I don't know and I am not saying that ER is good or bad..... I just want to know. I have never used ER on a knife BUT I do use it for other things and I like it.

https://evapo-rust.com/

Mike

Sharpnshinyknives wrote:

muskrat man wrote:OK fellas, apparently the go to for removing rust from virtually everything is to soak them in either vinegar or store bought liquid rust removers like evapo-rust, etc. While this method may be fine for certain items I DO NOT recommend it be used on folding knives. I have received 6 knives in the past 2 months that have suffered from this treatment. All of the owners mentioned seeing a YouTube video on knife restoration using this method (I did a quick search, and there is more than 1 ). In my very early days I tried using vinegar soaks on straight razor blades, the results were catastrophic. It somehow (I'm not chemist so I can't explain the HOW) stresses tool steels to the point of fracturing, 9 out of the 10 blades I had in the vinegar soak cracked. That being said I no longer use vinegar soaks on thin steel or for pocket knives in general. Now granted, in moderation it may be o.k I'm not sure how long this you-tuber recommended folks soak their knives in vinegar or if the owners adhered to these instructions or not. The bottom line is I have had these 6 knives come to me in the same condition from all over the country. They all feature broken backsprings (12 backsprings and counting) and I'm assuming the knives were not given a baking soda water rinse to neutralize the acids because they all come to me more rusted than they were before the owner attempted their "restoration".

This is a fine example of someone with limited knowledge publishing instructional videos that may or may not contain all of the information necessary to effect the desired result.

In my opinion, vinegar soaks are not for the purpose of "restoring" pocket knives.

I have in the past used 50/50 water vinegar soaks to remove rust from axe heads, steel traps, tools etc with little to no ill effect. I believe the hardness and thinness of the steel item being soaked has a great affect on the end result, not to mention the concentration of the liquid rust remover being used.

MM, I can tell you a little bit about why this would be damaging to a pocket knife. You are putting an acid in contact with two different metals, brass and stainless steel and a third nickel silver. It doesn’t take a chemist to recognize that you just created a battery. That reaction is breaking down the metal in the two dissimilar metals. Anytime you use something acidic on two metals your going to get this reaction. Being a chemical reaction it happens quickly and does more damage than you would think in a short time.
SSk

Thank you for that, makes sense now!

Meridian_Mike wrote:

Sharpnshinyknives wrote: MM, I can tell you a little bit about why this would be damaging to a pocket knife. You are putting an acid in contact with two different metals, brass and stainless steel and a third nickel silver. It doesn’t take a chemist to recognize that you just created a battery. That reaction is breaking down the metal in the two dissimilar metals. Anytime you use something acidic on two metals your going to get this reaction. Being a chemical reaction it happens quickly and does more damage than you would think in a short time.
SSk

Yep, that is why I was wondering about Evapo-rust....

From the ER web site....
"Best of all, Evapo-Rust® is safe to use: non-toxic, non-corrosive, and contains no acids, bases, or petroleum solvents."

I don't know and I am not saying that ER is good or bad..... I just want to know. I have never used ER on a knife BUT I do use it for other things and I like it.

https://evapo-rust.com/

Mike

Bi-metallic corrosion occurs ANYTIME you have 2 dissimilar metals in contact. Even 2 steels with different carbon content in contact with each other can create a galvanic action effect, albeit an extremely mild one. Steel to brass, steel to aluminum, aluminum to brass, any of the combos, will result in a battery effect. Add a little sweat and/or rain, and the corrosion rate accelerates. Add an acid, the electron flow rate goes up. Adding ANY liquid except oils to the mix boosts the RATE of corrosion. Oils act as an insulator and corrosive inhibitor. The liquid itself may not be corrosive, but it may "encourage' the rate of corrosion.

The "battery effect" is real. It can be more pronounced in folders since they typically have thinner pieces of metal involved. Thin will snap quicker than thick.

zzyzzogeton wrote:

Meridian_Mike wrote:

Sharpnshinyknives wrote: MM, I can tell you a little bit about why this would be damaging to a pocket knife. You are putting an acid in contact with two different metals, brass and stainless steel and a third nickel silver. It doesn’t take a chemist to recognize that you just created a battery. That reaction is breaking down the metal in the two dissimilar metals. Anytime you use something acidic on two metals your going to get this reaction. Being a chemical reaction it happens quickly and does more damage than you would think in a short time.
SSk

Yep, that is why I was wondering about Evapo-rust....

From the ER web site....
"Best of all, Evapo-Rust® is safe to use: non-toxic, non-corrosive, and contains no acids, bases, or petroleum solvents."

I don't know and I am not saying that ER is good or bad..... I just want to know. I have never used ER on a knife BUT I do use it for other things and I like it.

https://evapo-rust.com/

Mike

Bi-metallic corrosion occurs ANYTIME you have 2 dissimilar metals in contact. Even 2 steels with different carbon content in contact with each other can create a galvanic action effect, albeit an extremely mild one. Steel to brass, steel to aluminum, aluminum to brass, any of the combos, will result in a battery effect. Add a little sweat and/or rain, and the corrosion rate accelerates. Add an acid, the electron flow rate goes up. Adding ANY liquid except oils to the mix boosts the RATE of corrosion. Oils act as an insulator and corrosive inhibitor. The liquid itself may not be corrosive, but it may "encourage' the rate of corrosion.

The "battery effect" is real. It can be more pronounced in folders since they typically have thinner pieces of metal involved. Thin will snap quicker than thick.

I have written about this before on here. I believe it is the reason for the black spots that appear on knife blades as well. Many of those spots just happen to occur where the two metals are touching or close enough for the effect to happen. Just add a little sweat from your finger or just a little spittle from someone looking at the knife and coughing and it happens.
SSk

Great topic Kaleb, thank you for starting it, it has been very informative.

I was aware of electrolysis from my work in the 1970s on airless paint pumps. Most of the piston type pumps have a carbide ball check valve in them that prevents backflow. When a person merely rinses the pump out with water to remove the latex paint and then allows it to set with water in it that is when electrolysis took place between the carbide ball in the carbide seat. When the painting season started in the spring and early summer we would get a lot of pumps in the shop that wouldn't work because electrolysis between the ball and the seat had caused them to erode and they would not hold pressure. The preventative measure was to run a little bit of paint thinner and motor oil mixture through the pump which forced out the water, coated the ball and seek with oil and prevented electrolysis.

I have seen electrolysis in knives especially between steel and aluminum, but primarily in fixed blades.
I had not considered electrolysis taking place between dissimilar metals in a folding knife and how the presence of moisture, especially with salt, would cause accelerated corrosion because of the battery affect.
That would explain why corrosion is so rampant in saltwater environments. Essentially all of your tools with dissimilar metals have become batteries and are accelerating the corrosion process we call rust.

Very informative guys! It's amazing how much you can learn here on AAPK!

Research "hydrogen embrittlement."

Sharpnshinyknives wrote:

muskrat man wrote:OK fellas, apparently the go to for removing rust from virtually everything is to soak them in either vinegar or store bought liquid rust removers like evapo-rust, etc. While this method may be fine for certain items I DO NOT recommend it be used on folding knives. I have received 6 knives in the past 2 months that have suffered from this treatment. All of the owners mentioned seeing a YouTube video on knife restoration using this method (I did a quick search, and there is more than 1 ). In my very early days I tried using vinegar soaks on straight razor blades, the results were catastrophic. It somehow (I'm not chemist so I can't explain the HOW) stresses tool steels to the point of fracturing, 9 out of the 10 blades I had in the vinegar soak cracked. That being said I no longer use vinegar soaks on thin steel or for pocket knives in general. Now granted, in moderation it may be o.k I'm not sure how long this you-tuber recommended folks soak their knives in vinegar or if the owners adhered to these instructions or not. The bottom line is I have had these 6 knives come to me in the same condition from all over the country. They all feature broken backsprings (12 backsprings and counting) and I'm assuming the knives were not given a baking soda water rinse to neutralize the acids because they all come to me more rusted than they were before the owner attempted their "restoration".

This is a fine example of someone with limited knowledge publishing instructional videos that may or may not contain all of the information necessary to effect the desired result.

In my opinion, vinegar soaks are not for the purpose of "restoring" pocket knives.

I have in the past used 50/50 water vinegar soaks to remove rust from axe heads, steel traps, tools etc with little to no ill effect. I believe the hardness and thinness of the steel item being soaked has a great affect on the end result, not to mention the concentration of the liquid rust remover being used.

MM, I can tell you a little bit about why this would be damaging to a pocket knife. You are putting an acid in contact with two different metals, brass and stainless steel and a third nickel silver. It doesn’t take a chemist to recognize that you just created a battery. That reaction is breaking down the metal in the two dissimilar metals. Anytime you use something acidic on two metals your going to get this reaction. Being a chemical reaction it happens quickly and does more damage than you would think in a short time.
SSk

It's called galvanic action or galvanic corrosion.
Plumbers see it all the time...

This is a very informative thread. Thanks for the info, fellows.