How to completely remove a forced patina?

I am purchasing a knife that had a forced patina applied and the previous owner was only able to clean it up this far with flitz.



What is the easiest way to restore this close to new with least effort?

Clean it with BKF first and then remove the BKF patina with fingerstones or just some stone mud applied on cotton rounds. Shouldnt take more than 5min.

You can use a rust eraser to completely clean off the patina.
Rust erasers are abrasive enough that it will leave scratches, so you should follow the grain pattern on the steel.
I've used it on my carbon knife and it did clean the patina completely off and gave it that 'new' look. However, patina started forming quickly once I sliced that next onion... so you should ask yourself whether or not it's even worth it.

Here's a video by Jon about rust erasers:
[video=youtube;PpspXNdJ_IE]https://www.youtube.com/watch?v=PpspXNdJ_IE[/video]

I have forced patina once on a super blue steal blade (not coated) with winegar and used a stone powder (from 6000 grit synthetic stone) to remove it and it worked very well and fast.

EDIT: it was a very small utility blade (around 50mm), so full size gyuto would take a little more work. One could certainly use some of the polishing pastes for metas.

0000 steel wool with Flitz. May take two applications.

is the patina in this thread super undesirable? I tried forcing a patina on some swedish carbon this week and basically ended up with the pic above, hard to make out colours (I'm colourblind to boot) but the patina is more of a greenish gray colour with some orange tinges underneath- I was hoping for bluish grey. I know few of us are metallurgists but I was wondering if anyone could comment on what the difference between a "good patina" and "bad patina" (ie. desirability as opposed to "this is pitting") and what the good patina is a function of.... time? ph?

i have found a good way to get a uniform patina on swedish stainless it to use a vinegar bath for a couple of hours first, swedish carbon is quite reactive otherwise...

high grit wet/dry sandpaper

nortagem said:

You can use a rust eraser to completely clean off the patina.
Rust erasers are abrasive enough that it will leave scratches, so you should follow the grain pattern on the steel.
I've used it on my carbon knife and it did clean the patina completely off and gave it that 'new' look. However, patina started forming quickly once I sliced that next onion... so you should ask yourself whether or not it's even worth it.

Here's a video by Jon about rust erasers:
[video=youtube;PpspXNdJ_IE]

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Great advice I have done something similar

denfetafrukten said:

Clean it with BKF first and then remove the BKF patina with fingerstones or just some stone mud applied on cotton rounds. Shouldnt take more than 5min.

Click to expand...

Great advice been there done that I had some minor problems with scratches

spoiledbroth said:

is the patina in this thread super undesirable? I tried forcing a patina on some swedish carbon this week and basically ended up with the pic above, hard to make out colours (I'm colourblind to boot) but the patina is more of a greenish gray colour with some orange tinges underneath- I was hoping for bluish grey. I know few of us are metallurgists but I was wondering if anyone could comment on what the difference between a "good patina" and "bad patina" (ie. desirability as opposed to "this is pitting") and what the good patina is a function of.... time? ph?

Click to expand...

I hear you can stablise red rust by boiling it, turning it a dark color.

Stone mud, polish like Mother’s or Simichrome, very fine sandpaper (like Starcke Matador 7000), something like that.

lobby said:

I am purchasing a knife that had a forced patina applied and the previous owner was only able to clean it up this far with flitz.

What is the easiest way to restore this close to new with least effort?

Click to expand...

Leave it as it is.

BKF followed by warm soapy water.

Simichrome

Buff with diamond spray between 3-6 microns on a piece of hard felt. Works better than Flitz, BKF, Mothers and many other methods I've tried.

Benuser said:

Leave it as it is.

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I would also leave it. It looks great and should be stable.

As mentioned above, if you must polish it, any fine abrasive will do. 2000 or 2500 grit sandpaper will probably be a little quicker than the finer polishes like Flitz, Mothers or Simichrome. I expect that the previous owner just needed to use a little more elbow grease.

There are a lot of diamond pastes (of various grits) around which will do the job pretty quckly.

Just be careful when polishing that you don't cut yourself.

As long as the abrasive is finer than the original polish, you should end up with a similar finish.... unless you overdo it, in which case you may end up with a sort of semi mirror polish.