Hello, first time poster, however i have been browsing the forums for quite some time. ive been making knives for about a year and a half and have started getting into 'clay' coating. About a 8 months ago i attempted differential hardening using ruthlands furnace cement with mixed results, first one had a bad hamon (not too interesting, little wavy...) and bent it sideways, i was able to fix the warp. spurred on by my success i did it again, however i cracked the blade in 3 places and the edge snaked and i got discouraged... i have recently started up again and i opened my jar of furance cement and found it mostly dried out, however i managed to coat one blade, i have always used 1095 and i do a interrupted quench in 10% brine (3 seconds) then into canola oil for 3-4 seconds in and 3-4 seconds out. it cracked near the tip, and i snaked the edge, however i had left it thick enough to grind it down post heat treat and the crack was about 0.40 inches from the tip so i ground that down. The next one i got satinite coated a blade and did the same 3 second brine and then interrupted canola oil quench. I failed to surface prep the blade and one side blew off some time in the quench, resulting in no hamon, the blade also snaked even though it was thicker than i would normally quench.
Taking from my experiences, i made a new blade, left the edge much thicker than before, about twice the thickness of a knife that i would normally oil quench. i drew a template on it so the satinite was evenly applied, about a 1/4 of the edge exposed and decided to try only oil quenching. So i heat cured (stuck the blade in front of the forge) got a even heat, just past non-magnetic and quenched in cool canola oil and shook it around rather aggressively ( slicing motion to get a quicker than normal quench. The blade came out perfect. dead on straight, no warping no snaking no cracking. I took it to my grinder ground off the scale and satinite and could see the hamon in a low grit (100). Then i did a quick ferric chloride dip and it looked great. Tempered it at 375 and used a 60-62 rockwell scratcher thing and it would not scratch the blades edge but would the part where i had clayed it. . I should also mention that the unprotected part passed the file test and the clayed portion failed.
I did post heat treatment grinding and began to finish the blade and noticed there wasn't a hamon showing up. i got to 320 when i decided to race to 600 and do another acid test. The result was as this (in the picture, also freshly etched and before the oxides were even wiped away). Before during my first test, just to confirm i got a good pastern, it did a wave roughly every inch, just above the bevel, and out to about 3/4 of an inch from the ti
How could this happen, my blade never got more than pretty warm during the grinding ( i could still hold it bare handed) did i do something wrong in the quench or what? it is as if the hamon retreated. Suggestions...? Advice?
in case the above didn't work here is a direct link
http://i59.tinypic.com/15fm59k.jpg
Taking from my experiences, i made a new blade, left the edge much thicker than before, about twice the thickness of a knife that i would normally oil quench. i drew a template on it so the satinite was evenly applied, about a 1/4 of the edge exposed and decided to try only oil quenching. So i heat cured (stuck the blade in front of the forge) got a even heat, just past non-magnetic and quenched in cool canola oil and shook it around rather aggressively ( slicing motion to get a quicker than normal quench. The blade came out perfect. dead on straight, no warping no snaking no cracking. I took it to my grinder ground off the scale and satinite and could see the hamon in a low grit (100). Then i did a quick ferric chloride dip and it looked great. Tempered it at 375 and used a 60-62 rockwell scratcher thing and it would not scratch the blades edge but would the part where i had clayed it. . I should also mention that the unprotected part passed the file test and the clayed portion failed.
I did post heat treatment grinding and began to finish the blade and noticed there wasn't a hamon showing up. i got to 320 when i decided to race to 600 and do another acid test. The result was as this (in the picture, also freshly etched and before the oxides were even wiped away). Before during my first test, just to confirm i got a good pastern, it did a wave roughly every inch, just above the bevel, and out to about 3/4 of an inch from the ti
How could this happen, my blade never got more than pretty warm during the grinding ( i could still hold it bare handed) did i do something wrong in the quench or what? it is as if the hamon retreated. Suggestions...? Advice?
in case the above didn't work here is a direct link
http://i59.tinypic.com/15fm59k.jpg
. Get some Parks #50 and you will be happier. If you want to use brine, get some very clean W2 or switch to Hitachi white or blue steel.
I'm stuck, and not qualified to even guess what's happening. Even more confused since you tested the edge and spine with the 60-62 RC tester and they 'passed', so it's sounds as if decarb is off the list, since people are usually fooled by it when doin a file test because it makes it seem as if the edge didn't harden... but like you, I sure am interested in hearing what others have to say! 
sorry man..
