Need help with clay cracking on my knife before heat treatment

S

Sephigi

Joined
Mar 4, 2013
Messages
29
Just yesterday, I've been wanting to get a hamon ready on my big kitchen-style knife but when I put kitty litter on it the stuff cracks as I let it dry :mad:. What could be the problem? Is the pink clay I got cheap or did I leave some lumps in the mixture, which I have:confused:? Please, I need help, this is my first time differential hardening and I don't know why it keeps cracking while drying:(.
 
Kitty litter? Pink clay? Probably the problem is with what you are trying to use. People use Satanite and Rutland's furnace cement because they stick to the blade, can withstand high temperatures, and have some insulative properties. I've researched homemade blends for blade clay, and I see a lot of people frustrated by mixtures that won't stick to the blade. Particularly, clays that crack when drying or when heated.

You can find Rutland's almost anywhere. I like Satanite better, and that can be ordered easily online from hightemptools.com and others.
 
I'm no expert, but clay usually cracks when it is too thick or needs some structure (grog). Try mixing in some powdered fire brick and some newspaper pulp (shredded newspaper, water, blender).
 
Thank you all for the replies. I'm new here, but anyways, I think Satanite would be a great idea, but unfortunately for me I live in Mexico state and do not know where it can be found, perhaps I'll try harder next time. It is difficult to describe the type of clay that cat litter is other than it's color, but I heard that most litter is bentonite. JBroddrick I'll try to test those ingredients you have mentioned. Other than litter I've also tried this green clay, but still cracks equally. It sucks that where I live lacks rivers or seashores where clay is said to be found. Anyways, I'll be back and let you guys in on the results. Otherwise, I'll just have to give it a full quench and temper, like I did to my first bowie.
 
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JBroddrick, the refractory cement I made according to your ingredients has been very successful : ). No cracks and better adhesion than ever before, thank you so much. Never knew newspaper pulp and fire brick dust would be very helpful. Can't wait to get my first hamon, tonight.
 
Bentonite is not clay. It's not particularly waterproof either.
You could always edge quench in a shallow tray.
 
Ok, I just clay quenched my big spring steel knife in brine, with no cracks :), but no hamon yet. I might need either a muriatic-hydrogen peroxide (no ferric chloride available here) mix or polish to a 2k grit with lime juice. Once again, ty all for the replies. Oh yeah, I also skated the file a little on both the blade and spine, and therefore noticed a difference in wear resistance on both parts.
 
Sephigi said:
Ok, I just clay quenched my big spring steel knife in brine, with no cracks :), but no hamon yet. I might need either a muriatic-hydrogen peroxide (no ferric chloride available here) mix or polish to a 2k grit with lime juice. .
Click to expand...

What are you using for steel? Not all steels will show a proper hamon, no matter how you clay & polish it.

Warm vinigar may be a little more aggressive than lemon juice. [if there is a hamon hiding in there...]

Good luck & have fun!!
 
Oh yeah, most "spring" steels wont' really give you a hamon. You could get a quench line at most. 1065, 1075, 1085 will give you a hamon if they do not contain much manganese- but that's not common. 1095 will work, it's low mang and shallow hardening, as will W1 and W2. If you can find WHC (basically low mang 1075) that should be great, too.

Quench lines can be attractive, I have achieved them many times in 5160 with satanite mortar.
 
Well, Dewey. The steel that I quenched was an old, rusty leaf spring. Not sure if it's 9260 or 5160, but it sure ain't 1095. Salem, those are great kinds of steel, perhaps I'll see if I can buy them from Aldo. All I can ever get atm are old files or maybe rusty circular saws from open air markets and leaf springs (which I need for big knives) from scrap yards, which are pretty small compared to the ones in the USA.
 
Despite all efforts, I still can't get a hamon to pop, but thank you all once again for helping. I'll just have to get over it til I get different steel. In the meantime, I'm gonna try to post pictures of my first Bowie and kitchen-esque knife.
 
You are not going to get a hamon to "Pop" on a steel that has that much chromium. You need a low allow steel like W2. 1095 will also work.
 
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