How thick should the clay be for a hammon?

Tom Lewis said:
To get a good hammon, does it matter how thick the clay is on the blade?
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Yep. you should have the thinnest possible coating on the edge that you wish to harden and a thickerportion on the spin that you wish to remain soft as well as the ashi lines extending down into the area that will be hardened. the thick clay should be no more than 1/8th inch. If you are using parks 50 oil then you don't really need to have the thin clay on the edge. if your heat is just right the hamon will be almost exactly follow the clay. too hot or too cold and the hamon will push up or down the blade but not neccessarily in the way you would expect.
 
Gday guys,

What is the advantage in having a "thin as possible" coating on the edge? I would have thourght you would want this bare so you could watch the colour etc before quenching.

Cheers Bruce
Barnett Custom Knives-Australia
www.barnettcustomknives.com
 
bbarnettAUS said:
Gday guys,

What is the advantage in having a "thin as possible" coating on the edge? I would have thourght you would want this bare so you could watch the colour etc before quenching.

Cheers Bruce
Barnett Custom Knives-Australia
www.barnettcustomknives.com
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I think in Stacy's longer post, the thin coating helps prevent decarb.
 
bbarnettAUS said:
Gday guys,

What is the advantage in having a "thin as possible" coating on the edge? I would have thourght you would want this bare so you could watch the colour etc before quenching.

Cheers Bruce
Barnett Custom Knives-Australia
www.barnettcustomknives.com
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Hey Bruce and gday back at you. S Fowler has stated the biggest reason for the thin coating on the edge. Considering the time and temp that the blade is at when hardening I don't believe that decarb is a problem. the very thin coating doesn't seem to impeed my perception of the color by any noticeble amount. I have started doing my hardening in the dark and have seen a decrease in failures and my hamons have been following the designs in the clay almost exactly since doing so. I am quenching in water for the most part because I want the natural organic curve that a water quench gives.
 
Clay thickness also depends on blade thickness. I have tried clay coating a few blades that were slightly thinner than 3/16ths and there was 1/4 inch of clay on either side and it hardened right up underneath that clay, using 1084.
 
Sam Salvati said:
Clay thickness also depends on blade thickness. I have tried clay coating a few blades that were slightly thinner than 3/16ths and there was 1/4 inch of clay on either side and it hardened right up underneath that clay, using 1084.
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1084 has manganese in it which makes it deeper hardening. I have also had this happen when hardening in oil using a furnace and a short soak (5 min). My best hamons come from quenching in water using a for to austenitize and not allowing the spine to reach critical. Also my worst failures:confused:
 
Good point Bill I forgot about the manganese, I wonder if results would have been different with 1075? What steel do you use for getting hamons Bill?

When you heat in a fire and do not allow the spine to reach critical, is one of your worst failures where you got a longitudinal crack right along the line of clay? It has been my fear that that would be a problem encountered with that method.
 
Gday guys,
Thanks for the answers on that, all makes sense now.

Sam, Bill, I clay coated(not the edge), short soaked and oil quenched a 1080 blade last time I was at Keiths and it almost fully hardened, it stopped about 1/2" in front of the ricasso. Get it in the right light and you can just pick out a hamon line. Its only a small blade so may do some destruction tests on it :eek:

Cheers Bruce
Barnett Custom Knives - Australia
www.barnettcustomknives.com
 
1060, 1065, 1075, 1080, 1084 are all high in manganess and deep hardening but not quite a deep as higher alloy steels, like 01, L6, 5160 etc..

W1, W2 and 1095 are low in manganese and very shallow hardening.

1050 is high in manganese but with carbon that low it is able to produce hamon.

Shallow hardening steels are best for hamon and will show the most activity.
 
Sam Salvati said:
Good point Bill I forgot about the manganese, I wonder if results would have been different with 1075? What steel do you use for getting hamons Bill?

When you heat in a fire and do not allow the spine to reach critical, is one of your worst failures where you got a longitudinal crack right along the line of clay? It has been my fear that that would be a problem encountered with that method.
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Hi Sam,

The best hamon that I have ever got was on a 1095 blade. I am getting great results now with Dons w2.

i have never had a blade crack longitudinaly but I have broke hell out of the perpendicular to the edge. the best (worst) one had a crack every quarte inch or less. felt like shuffling a deck of cards.

This is the knife with my best hamon but it don't show up great. I think I have better pictures of the blade i'll try and post.
84637_6_b.jpg
 
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