Forced patina questions - rust?!?

[TheBlindHarper]

Afternoon guys, hope all's well, never member here.

I did a forced mustard (wholegrain Dijon, if you're wondering...) patina on my Mora 102 yesterday evening. I left it to sit for perhaps 30 minutes and it came out quite nice, apart from one little thing I noticed...

I wiped all the mustard off with paper towel, then rinsed the blade thoroughly, dry off totally, rinse & repeat multiple times until I was certain all mustard was gone.

Now, about an hour after this I was just admiring the nice patina, and noticed some rust. On the top face of the bolster - Where the tang comes down through - some bright orange rust had appeared. Any ideas how this has came about so quickly? I have a guess:

The mustard-steel-oxygene reaction is basically "opening up" the steel in a fashion, and perhaps I haven't neutralised the reaction properly, hence when some water has gotten trapped in the bolster, the water-steel-oxygene reaction has had a perfect environment to work in, due to the already compromised top layer of steel. Does that make any sense?

What should I do the solve this, and is my idea at all correct?

Thanks

 

[Mr Wolf]

Welcome

 

[Janne]

Forced patina is a form of rust.
My guess is that a bit of water got trapped under the bolster, and started a bit of 'classic' oxidation. Water + Oxygen + Iron = Rust
My advice would be - clean it up, dry it properly ( all water gone between bolster and steel) then put a little bit of oil there. Raw Linseed oil was used with sucess in the past.
Gun oil is good too, if you have it.

Forced oxidation will not prevent rust 100%.

Another good way to lessen the rate of oxidation is to use a Gun Blueing solution.

 

[TheBlindHarper]

Forced patina is a form of rust.
My guess is that a bit of water got trapped under the bolster, and started a bit of 'classic' oxidation. Water + Oxygen + Iron = Rust
My advice would be - clean it up, dry it properly ( all water gone between bolster and steel) then put a little bit of oil there. Raw Linseed oil was used with sucess in the past.
Gun oil is good too, if you have it.

Forced oxidation will not prevent rust 100%.

Another good way to lessen the rate of oxidation is to use a Gun Blueing solution.

Good of you to mention the gun oil. I do have some actually, never occured to use it!
To clean it up, shall I just take some white vinegar and wire wool to it?

 

[Janne]

The forced rust layer = Fe3O4
Red/ classic rust = Fe2O3

I googled it.

I do not know what the Catsup has for function. Catalyst? No clue!
People swear by a Potato.

 

[Janne]

Sounds stupid, but I would first brush off the loose bits, then use vinegar on the red rusted part, carefully, toothbrush off loosened bits, then wash off with a baking soda solution. This will neutralize the acid.
Then dry ( hair dryer) then a bit of gun oil.

(

Try the potato method next time. (I have never used it myself). Easier to control.

I assume the knife is a 'classic' one, with a birch wood handle?

They all rust inside the handle, given time.

 

[TLM]

Magnetite Fe3... is the preferred form because it flakes off less than Fe2... when in contact with water. Neither one is very stable though. Parkerizing with phosphoric acid is more stable and can apparently be varied in colour from grey to black. Several recipes can be found. On stainless steel the easiest passivating solution is hot citric acid/water. It does not change the colour much.

 

[Janne]

Gun Blue is fairly stable, if done properly. But I have found that most surface treatments wear off when you use a knife, cutting wood and similar.

Even that Grey-Black stuff they put on Fallkniven knives scratches wears.

Ever owned a watch with a DLC coating? Comes off. It is the join between the coatings and steel that fails.
Rust is hard. A good polishing medium. But it does not adhere well.

 

[TheBlindHarper]

Sounds stupid, but I would first brush off the loose bits, then use vinegar on the red rusted part, carefully, toothbrush off loosened bits, then wash off with a baking soda solution. This will neutralize the acid.
Then dry ( hair dryer) then a bit of gun oil.

(

Try the potato method next time. (I have never used it myself). Easier to control.

I assume the knife is a 'classic' one, with a birch wood handle?

They all rust inside the handle, given time.

Perfect reply, thanks Janne. Aye a "classic", red painted birch handle. Lovely little knife for an also very little amounts of money!
Potato method? And does it have to be white vinegar, or will malt work?

 

[eraaij]

Perfect reply, thanks Janne. Aye a "classic", red painted birch handle. Lovely little knife for an also very little amounts of money!
Potato method? And does it have to be white vinegar, or will malt work?

Once cleaned up to satisfaction, it might be a good idea to fill up the space between the (poorly fitting) bolster and tang with some transparant epoxy. This will prevent rust inside the handle.

Cheers,
Emile

 

[TheBlindHarper]

Once cleaned up to satisfaction, it might be a good idea to fill up the space between the (poorly fitting) bolster and tang with some transparant epoxy. This will prevent rust inside the handle.

Cheers,
Emile

Thanks Emile, and yes the bolster is rather poorly fitted. The one side is really quite bad, the other is passable but not perfect. Rather untidy job done of it. It's a shame, as it's my first Mora and the blade itself is of great quality and, functionally, it is a great little knife and perfect for my needs. It hasn't put me off Mora knives, though perhaps next time I will purchase a blade blank and haft it myself.

 

[Janne]

Perfect reply, thanks Janne. Aye a "classic", red painted birch handle. Lovely little knife for an also very little amounts of money!
Potato method? And does it have to be white vinegar, or will malt work?

You stick the blade in potatoes, and let it be there for a time.
Any vinegar.

 

[demographic]

When I had my multi pass welds tested they used to etch the cut sections with phosphoric acid, it showed up each individual run/pass and its structure and provided a greyish colour and some element of protection.
I kind of preferred it to these forced patinas but really I just prefer stainless steels for most knives.

Plane blades? Well as most times my handplanes are used indoors I'm not so fussed about stainless. Can't say Ive ever even heard of stainless steel handplane blades and even if there was some it's not anything I would search out.

 

[Janne]

Modern gun blue contains Phosphoric acid. I use it a lot in work, and sometimes take some home for deep cleaning rusted steel.

I have started to use Evapo Rust though, and it is superior in all apects.
Then use various brands of Gun Blue, depending on required end colour.