Forced Patina on a 80CRV2 blade question

[John Cahoon]

Hello everyone, I have a special order for a friend of my nephew who wanted a gray blade. I have fooled around with etching but never delivered a finished blade. Mostly just post HT "decarb softening" in diluted muriatic acid from the pool store. Well as you might expect I'm getting streaks and uneven results. Had some luck in the search engine but here's what I've done:

80CRV2 hand sanded to 600 grit at 60-61, cleaned with soap/water then wiped down with denatured alcohol. I wore clean white nitril gloves while handling.

The acid is diluted probably at least 5-1 with tap water (softened water common to the desert SW US). The solution is at least 2 years old in a capped 4" PVC pipe.

So I've seen where Stacy in an old thread said to use 400 grit, also seen people say to "swish it around" maybe? Are there any other recommendations? TIA!

P.S. he wanted a gray wood handle too and what I've done so far is use water soluble coal black leather dye from Tandy, diluted with water to achieve decent results on that.

 

[imill3567]

I actually start with alcohol or acetone then finish with hot water and dawn dish soap I find that doesn’t leave any streaks.

 

[John Cahoon]

Hi imill 3567, thanks I'll reverse the order. I'll also mix up a fresh supply and put the pipe on a single burner camp stove outside in a pot of water to heat it up to warmish as I had read about others doing that. We'll see what happens

 

[samuraistuart]

Also you might consider a dash of dish detergent which acts like a surfactant. I always use a healthy dose of dish soap when doing hamon etches to get a more even coating.

 

[John Cahoon]

Hi samuraistuart can you be more specific on details please? Are you saying rub on liquid dish soap before dropping it into the acid solution?

 

[Blackdirt cowboy]

Maybe I’m not understanding exactly what he wants, but why not just etch it in vinegar? I did that with a 8crv2 knife a while back and it came out great. Of course I ground the bevels after the etch so they were shiny, but I left the flats etched.

 

[A.McPherson]

Hi samuraistuart can you be more specific on details please? Are you saying rub on liquid dish soap before dropping it into the acid solution?

No just drop some dish soap in the etchant to make it so the surface tension breaks easier. It'll coat your blade better.

But yes wash your knife with hot water and soap beforehand. No oils on the blade will result in less streaking

 

[John Cahoon]

Thank you Mr. McPherson I get it now. And vinegar is always an option but since I had the muriatic solution on hand that's what I went with on the first try.

 

[imill3567]

Yeah I do usually use hot vinegar as the etchant when I want a grey base color to put a mustard patina on. I stick the knife in the vinegar and pop it in a 180deg oven for about 30min.

 

[Stacy E. Apelt - Bladesmith]

Pool supply muriatic acid is 20°Baume or 31%. Diluting only 5:1 drops it to around 6%, which is still pretty strong.
When the acid is too strong, the bubbles make tracks along the blade surface as they rise and cause streaks. Also, the oxide sludge can block some areas from etching and make splotches.

FC is far better than muriatic acid. White vinegar is suitable substitute.

I won't go into the formula and procedure here, but you can make your own FC with steel wool and muriatic acid.

 

[Natlek]

Thank you Mr. McPherson I get it now. And vinegar is always an option but since I had the muriatic solution on hand that's what I went with on the first try.

You should try Phosphoric acid ...........it last much longer that anything else i try .
https://bladeforums.com/threads/phosphoric-acid.1654333/

 

[John Cahoon]

thanks Stacy and Natlek, I'll be making a list, checking it twice and give it a go. If it looks good I'll post a picture. If it doesn't I won't!

Stacy do you think 3% muriatic solution would be better or some other proportion?

N Natlek did you brush that on? I see the little blue bowl with the wood chip in it but wanted to make sure. Pretty sure I can locally source some Phosphoric acid around here. Your two tone blade looks real interesting.

 

[Stacy E. Apelt - Bladesmith]

Yes, 10:1 dilution will give more control. I personally don't like muriatic acid except for working on a hamon where I dilute it 30:1.

 

[Cliff Carter Knives]

Ferric is fairly cheap and can be bad quickly from Amazon. I’ve found the ratio of FC to water isn’t something that needs to be very precise. I like it strong so I usually go 1:2.

to avoid streaking, pull the blade every 5 or so minutes and rub with some 000 steel wool then rinse. Then back in the ferric. This will give you a nice even, smooth finish and remove any light or dark uneven spots.