the wetted surface?

[bushboy]

When heat treating I start from the tips to the handles,is this the norm?I notice as I get on the inner third a wetted line appears(for lack of a better term) and the colour of the heat treated limb goes to a wavy moisture looking line and the limb goes to a lighter colour even after the same heat is applied into the handle.any thoughts as to what is happening here?

[PatM]

 Likely the thicker your section of limb is the damper the wood still is. How long has this stave dried? It looks just like you are chasing moisture down the limb.
 If you  try to force dry wood with heat the pressure of the expanding air in the hollow tubules forces moisture out ahead of the advancing heat.
 Depending on the wood there can be more or less oily resin that mixes with the moisture and produces uneven heating and charring.

[bushboy]

It's a kiln. Dried ash board,I've seen it in elm and osage also.

[Badger]

  I have seen that several times now, looks like moisture is being chased down the limb. I changed the way I heat treat now. I go from tip to handle back and forth at about 4 seconds per swipe. Depending on the wood the smell is what tips me off that it is done. I spend about 15 min per limb but I don't toast at all unless I am trying to recurve something and just get it a bit too hot. The color get a bit darker but not toasty looking.