Well, I don't know what I do different, but I sand my blade to 220. Put on the wet Satanite and go straight to the forge.
Dry it in front of the forge door a couple times to let the steam out of the clay. You need to do this gradually. If you get it TOO HOT while it's still wet, it cracks. Fractures.
And that cracking and fracturing sort of LIFTS it off the blade and it's no longer connected to the surface.
Just do it gradually. Takes all of 2 minutes.
Sort of bake it on.
When I get my blades out of quench, I swear, I have a hard time getting the clay OFF! I even have a Corian chisel I made to clean the blade off.
The other issue is that 9 out of 10 guys will put on waaaaaaaaaaaaaay too much clay.
Considering that when we speak of hamons we are normally talking about the ultra shallow hardening blades of W1 and W2, you can get a nice hamon with no clay at all - just by manipulating heat.
So, with that in mind, why use clay that's 1/8" thick?
Not necessary.
I literally put my clay on with a paint brush. Has almost immmeasurable thickness.
So I think it's the thickness that is the problem with cracking and falling off.
Too much moisture within the thickness, and when it dries out it cracks.
Keep using less and less clay and see what happens.
A single 1 pound coffee can of Satanite should almost last a life time.
All that said, when talking about hamons, guys also go right to thinking that when they can't FIND the hamon, that there's something wrong with the clay procedure.
That's NOT usually the case.
You can't expose something that's not there.
And when trying to get the hamons that we all see, there's a couple things you need to do, or you simply won't get it.
Fast steel. (Shallow hardening W1 or W2)
Fast quench. Parks 50.