scale prevention/removal

R

redd1981

Joined
Oct 4, 2011
Messages
251
Hello guys since this is my first post I would like to say Iv been stalking the forums for a little while and this place is awesome!! I have been collecting knives since before I was even old enough to have them (trading the older kids in the neighborhood baseball cards or bike parts for knives, throwing stars etc.. and hiding them under my bed :D ) and have wanted to make them for years and years.

Anyways I started my first one and after annealing had a lot of scale on the steel. I found an old slightly dull chisel worked to scrape it off but I was wondering if there was a better way to remove it or prevent it all together. Any help would be appreciated.
 
Fastest easiest way I've found is to sand blast it off. I hate the smell of vinegar so I try to avoid that whenever I can :D
 
Three days in the vinegar works wonders. No pitting.

For future reference; a 5 inch cup stone on a 7 1/2 inch right angle grinder is the best tool there is.

Fred
 
Vinegar is about the gentlest thing that works.
That said, I found a napkin holder that I'd thrown in the vinegar bucket a couple months ago- it had gone from 1/4" down to about 16 ga!
Got a good chuckle out of that, fortunately it wasn't anything particularly valuable.
But no, it doesn't tend to pit metal at all, in my experience.
I did try the Pepsi trick on some steel, and it really softened some nasty heavy mill scale that had to come off, over night. Easy peasy to grind it off afterwards, instead of ridiculously hard.
Andy G.
 
You shouldn't really worry about pitting after annealing. You grind after you anneal unless you meant that you want to remove scale after tempering.
 
You can prevent a lot of it with a reducing atmosphere.

You can remove it fast with a Dremel or small die grinder.

Jewelers pickling compound (sodium bisulfate) works better than vinegar without the fumes.
 
For about $15.00, Brownell's will sell you a product called ATP 641. This is a liquid ceramic substance that is painted on the blade and allowed to dry before heat treating. It comes off easily in the quench and I have had good results in preventing scale with its use on O1. The blade has to be warmed slightly for good adhesion and it takes a couple of hours to dry before HT.

Good luck and welcome to the forum.

Dick
 
I second what Tai said abvouit sodium bisulfate. It's the stuff you put in the toilet to remove rust stain.
 
I have had luck preventing excessive scale with a very thin wash of satanite (just using what I have on hand). When I need to leave a blade in my HT kiln, I just mix up a thin wash and smear it over the blade. Although there are better methods, this seems to work ok for me.
 
steveo83 said:
I have had luck preventing excessive scale with a very thin wash of satanite (just using what I have on hand). When I need to leave a blade in my HT kiln, I just mix up a thin wash and smear it over the blade. Although there are better methods, this seems to work ok for me.
Click to expand...

what is "satanite"
 
It's used for coating blades to make hamons mostly (at least that's what I use it for) but it's sold through this supplier: http://www.hightemptools.com/refractorycoatings.html

You basically mix it with water as thick or as thin as needed.

Importing it into oz was fun. It came shipped in a ziplock bag wrapped in newspaper with big black writing on it "SATANITE". I'm sure customs thought they'd hit the jackpot when they first inspected the package. They just sent me a seizure notice and wouldn't release it until the MSDS was supplied. All good after that, I'll be ordering more this month.
 
Satanite is a refractory coating used to cover the kao-wool lining in forges and to seal up the joints between firebricks. It is mixed with water to make a mortar.

For heat treating blades,it is mixed to about the consistency of heavy cream.You put a thin coating on a blade and allow it to dry. This will protect the steel from the oxygen and prevent scale.

It is also used to make a hamon. The thin wash is applied and dried, then a slightly thicker coating is applied to the sides and spine of the blade. It is wiped away from the edge area. In the HT the spine will become pearlite and the edge martensite. It is a lot more complex than that, but that is the basics of getting a hamon. It will only work on shallow hardening steels, BTW - 1905, W1, W2, and any very low-manganese/low-alloy simple steel.
 
rasret01 said:
For about $15.00, Brownell's will sell you a product called ATP 641. This is a liquid ceramic substance that is painted on the blade and allowed to dry before heat treating. It comes off easily in the quench and I have had good results in preventing scale with its use on O1. The blade has to be warmed slightly for good adhesion and it takes a couple of hours to dry before HT.

Good luck and welcome to the forum.

Dick
Click to expand...

Yep. Great stuff. I use it for all my HTing. Blades come out gray and mottled in color, and no scale or pits.
 
You must log in or register to reply here.
Back
Top