TOPS knives CAT rusty in engraved parts of blade

D

damib

Joined
Jul 7, 2021
Messages
119
Hello,
I used my TOPS knives CAT for applying mustard on bread and it developed little bit of red/dark brown rust after cleaning it with water. I don't really think it was the mustard as the water was almost hellishly chlorinated and is non-drinkable due to pollution. I was able to get rust off the edge easily, but it is still stuck in some parts of engraved parts of the blade (where the model name of knife is). Should I worry that it will go deeper? I use the knife almost everyday.
 
Spray it with oil. The knife is building character. Use it as much as possible. I wouldn’t worry about the patina going deeper. Perfectly normal stuff for 1095 to develop patina with use ( or any high carbon steel ). Post some pics please ! Used knives are the best knives.

You could always hit the logo with a WD40 soaked toothbrush and get a lot of that orange ish stuff out - go lightly.

731709E3-918A-4016-8879-AE2DE1945B2A.jpeg

Patina is beautiful 👍. This one is just getting started.
 
Many people use mustard to create a forced patina - don't be too quick to say you don't think it was the mustard. It most assuredly was. :)

Here are a couple examples of a mustard-only patina on my knives. They have been used, and then re-done several times with mustard:

aM002RR.jpg
 
shane45-1911 said:
Many people use mustard to create a forced patina - don't be too quick to say you don't think it was the mustard. It most assuredly was. :)

Here are a couple examples of a mustard-only patina on my knives. They have been used, and then re-done several times with mustard:
Click to expand...

I don´t really think it was mustard only because vinegar (one of main components of mustard) is supposed to create black patina. Not red or dark brown.
 
damib said:
I don´t really think it was mustard only because vinegar (one of main components of mustard) is supposed to create black patina. Not red or dark brown.
Click to expand...

I have done it dozens of time on dozens of blades. It is the mustard. It will leave a brownish oxidization, but once that is removed you will be left with a dark pattern per my pic above. :)
 
shane45-1911 said:
I have done it dozens of time on dozens of blades. It is the mustard. It will leave a brownish oxidization, but once that is removed you will be left with a dark pattern per my pic above. :)
Click to expand...
Thanks. It would be interesting to see what happens there in terms of chemistry.
 
damib said:
Thanks. It would be interesting to see what happens there in terms of chemistry.
Click to expand...

It is simply the acetic acid in the mustard (which is made up of a percentage of vinegar, which you stated) reacting to the carbon in the steel. It causes it to rust (oxidize) at a greatly increased rate. However, once the surface oxidization is removed, the patina that is left is basically a stain and no longer active oxidization assuming you have neutralized the mustard (vinegar) with baking soda, or a good thorough rinsing of warm, soapy water.
 
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shane45-1911 said:
It is simply the acetic acid in the mustard (which is made up of a percentage of vinegar, which you stated) reacting to the carbon in the steel. It causes it to rust (oxidize) at a greatly increased rate. However, once the surface oxidization is removed, the patina that is left is basically a stain and no longer active oxidization assuming you have neutralized the mustard (vinegar) with baking soda.
Click to expand...
I like what you did there. So how did you manage to get one darker than the other, with the forced patina?

Does forced patina work the same way on stainless?
 
TheArab said:
I like what you did there. So how did you manage to get one darker than the other, with the forced patina?

Does forced patina work the same way on stainless?
Click to expand...

It is hard to ever get the same pattern or tint on different knives. There are too many factors involved (time that the knives were soaked in mustard, thickness of the mustard applied, percentage of carbon in the blade, relative humidity, air temperature, etc.).

You cannot get a patina on stainless steel with vinegar or mustard - you need something much stronger. Ferric chloride is typically used. Ferric chloride is much harsher than mustard or vinegar (and much more corrosive - safety first, kids). Ferric chloride will not usually give such a dark black coloring however, and is often just shades of grey - even with repeated applications.

You can do some neat things with ferric chloride however. Here is a blade that was etched with ferric chloride that I dissolved a bit of copper in, first:

vA7iV0D.jpg


(Sorry for taking this a bit off topic damib.)
 
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shane45-1911 said:
It is hard to ever get the same pattern or tint on different knives. Too many factors involved (time that the knives were soaked in mustard, percentage of carbon in the blade, relative humidity, etc.).

more corrosive - safety first, kids). Ferric chloride will not usually give such a dark black coloring however, and is often just shades of grey - even with repeated applications.

You can do some neat things with ferric chloride however. Here is a blade that was coated with ferric chloride that I dissolved a bit of copper in, first:

vA7iV0D.jpg


(Sorry for taking this a bit off topic damib.)
Click to expand...
Thanks for all that..

Sorry OP, hope your knife ends up looking good.
 
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