Forced Patina on Stainless Steel blade

[blandies]

I had decided to try and put a striped design patina on an old cheap military surplus balisong I had lying around. It says "Stainless" on the knife so I am not sure what the steel is exact. It is polished to a mirror finish.

I read that Patina could not be put on stainless steel, well... I just did I believe, unless this is not a full on patina. I used regular mustard and painted my design on and let sit for about 50 minutes. I got the exact look I wanted but it only shows when you don't have light shining from the mirror finish. When you can see it it really stands out.

My question...is there a way to get it more noticeable next time? Maybe leave it on for 5 hours? And how come I was able to get a patina on stainless. I may have read wrong but I didn't believe you could force it on stainless steel.

Here are some pictures. It was really hard to get a good picture with the computer screen reflecting on the blade...I used my web cam. Sorry for the quality.

 

[Obsessed with Edges]

Even 'stainless' steel can oxidize, one way or another. And a 'cheap military surplus' knife is like the proverbial 'box of chocolates' (never know what you're going to get, steel-wise). I'm assuming the manufacturer and country of origin are unknown? The steel could be anything, so the fact that it took a patina at least shows it's barely stainless (if that). Even some well-known non-stainless steels can have a little bit of corrosion resistance, depending on what's in the alloy. That means they're less likely to rust as easily, but might still oxidize (patina, a.k.a. 'black oxide'). Case's CV steel is known for this. And D2, which is straddling the fence between stainless and not, is also well-known for darkening a little bit, but rarely rusting outright. It all depends on what mix of ingredients are in the particular alloy. Most 'reputable' stainless steels don't rust or patina, but some manufacturers in certain other countries might have a more 'relaxed' definition of what 'stainless' means.

If you're looking to enhance the patina a little, a slightly less polished finish on the blade might help that. Polished steel has less pores/nooks/crannies for oxidation to bond to & take hold, so it won't oxidize as easily (either rust or black oxide). Polishing is one way to help protect a non-stainless blade from rust (or minimize it, to the extent that it can be). So, if you're wanting to enhance the oxidation a little, doing the opposite might help. Might 'satin' the finish a little bit, with a Scotch-Brite pad or some wet/dry sandpaper (600-1000 grit should do; try the higher grit first). Then try the patina process again.

 

[blandies]

Thanks for the bit of info! When my 154cm comes in I was going to put it on there but I guess there's no point in trying now since it would not work. It's a shame, patina can look real nice when applied right.

Maybe if I taped where I wanted it left alone and had the knife sandblasted I can get a pattern out of it.

 

[parbajtor]

Thanks for the bit of info! When my 154cm comes in I was going to put it on there but I guess there's no point in trying now since it would not work. It's a shame, patina can look real nice when applied right.

Maybe if I taped where I wanted it left alone and had the knife sandblasted I can get a pattern out of it.

That's what I would have suggested.

 

[GrizzlyBear]

This blade has 154-CM stamped in it. It is from a copy of a Lightfoot LCC produced by a company called High Desert (called the Fox).

What I did here was several long soaks in straight muriatic acid. Each soak ended in a baking soda bath, then a rinse in clean water, then dried and lightly hit with extra fine steel wool. This established a nice, deep grey color. What I did next was PURE experiment...I wanted to make patterns on the blade with the acid. So, I tried brushing it on in swipes, hoping the acid would take hold and color the steel...nope. So, I took some plain yellow mustard and mixed in some of the muriatic acid and mixed thoroughly. Then I laid on my patterns. Voila! It worked!

Here is why I think it worked. Once my initial soaks were finished, the acid apparently "opened up" the surface of the steel...so to speak. Then, when the acid was mixed with yellow mustard, the combination of vinegar and acid allowed the fresh steel to etch and color up nicely.

Whether the blade is actual 154-CM is unknown...if it is, it has a carbon content of 1.05 which is another reason I think it took the etch so well.

But, I did do quite a bit of research on forcing a patina or darkening stainless steel on the knives that I make. Usually, the higher the level of chromium, the more the steel resists darkening....the addition of nickel in some steels makes this even more so.

However, it is not unheard of to darken stainless. Several things can be used/tried:
-Sulfamic acid crystals
-Ferric Chloride
-Muriatic Acid
-Bleach (commercial grade)
-They even make a specialized black oxide coating for stainless that works quite well!