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 Post subject: Sulfamic Acid
PostPosted: Mon May 26, 2014 7:43 am 
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Joined: Mon May 19, 2014 1:52 am
Posts: 354
Location: Philly
Anyone ever use sulfamic acid to force a patina? Looks like the patina it forces can be jet black and if left on long enough it will even patina stainless steel.

Its a pretty heavy duty acid. A lot of silver polish and tarnish removers have it as an active ingredient as well.



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 Post subject: Re: Sulfamic Acid
PostPosted: Mon May 26, 2014 1:07 pm 

Joined: Wed Feb 20, 2013 2:22 am
Posts: 662
I've seen varying opinions on whether the patina formed by sulfamic acid is indeed protective. If I was going that route I would probably try rust blue, aka Belgian blue. Stay away from nitre blue due to the high temps required.

Cheers,

Rick


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 Post subject: Re: Sulfamic Acid
PostPosted: Mon May 26, 2014 7:07 pm 

Joined: Tue May 29, 2012 12:29 am
Posts: 864
Ferric chloride


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 Post subject: Re: Sulfamic Acid
PostPosted: Mon May 26, 2014 10:53 pm 
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Joined: Mon May 19, 2014 1:52 am
Posts: 354
Location: Philly
That stuff sounds even better. I would probably just stick with boiled apple cider vinegar I'm not a chemist hah so i'm not gonna be messing with anything crazier just curios to see who gets hardcore and busts out the real acids.



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 Post subject: Re: Sulfamic Acid
PostPosted: Tue May 27, 2014 4:13 am 

Joined: Wed Feb 20, 2013 2:22 am
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COP<> Ferric Chloride is a popular etchant. Nitrates and nitrites passivate steel, as has been discovered by those who tame reactive knives with salami or corned beef (what I use). What I was trying to point you towards is rust bluing, which combines the two, adds nitric acid, and often throws in a secret sauce. The secret sauce isn't gonna be something easily sourceable.

I'm considering trying this on one of my white #2s.

http://www.brownells.com/gunsmith-tools ... d9815.aspx

Cheers,

Rick


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 Post subject: Re: Sulfamic Acid
PostPosted: Wed May 28, 2014 12:32 am 

Joined: Wed Mar 05, 2014 2:28 am
Posts: 231
The gunsmith solution is interesting, I would make sure its food safe before putting it to knives


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 Post subject: Re: Sulfamic Acid
PostPosted: Wed May 28, 2014 3:51 am 

Joined: Wed Feb 20, 2013 2:22 am
Posts: 662
The formula I linked to should be food safe. Herter's original Belgian blue formula contains mercury salts. Not sure if any sticks around to play Mad Hatter after the distiller water boil, but I wouldn't chance it.

Cheers,

Rick


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 Post subject: Re: Sulfamic Acid
PostPosted: Wed May 28, 2014 2:56 pm 

Joined: Tue May 29, 2012 12:29 am
Posts: 864
A blued knife is going to make food taste bad.


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 Post subject: Re: Sulfamic Acid
PostPosted: Fri May 30, 2014 5:00 pm 

Joined: Wed Feb 20, 2013 2:22 am
Posts: 662
Jason<> Not poking a finger in your eye here, but do you have any experiences to back that up? Because chemically a rust blued knife should be identical to one with a natural patina.

If I get the urge I might try Mark Lee's Express Blue #1 on my white #2. When I get the MSDS I will post ingredients in this thread. Only problem is that the Sakai Yusuke isn't a problem child wrt reactivity (barely reactive) so I would only be doing it for aesthetics. And I don't want to dork up my new Kono Fuji. Hmm.

Cheers,

Rick


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 Post subject: Re: Sulfamic Acid
PostPosted: Sat May 31, 2014 10:53 pm 

Joined: Tue May 29, 2012 12:29 am
Posts: 864
I can't speak for all bluing, I used cold blue many years and was unhappy with the overall results. I've use onions, lemons, vinegar and currently ferric chloride, I'm sticking with the ferric chloride.

When it comes to knives I've tried about everything ;)


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