setting pitch

[Den Socling]

Jim,

I'm sure that there are bonds between compounds that affect boiling point but don't you agree that Tom's explanation is basically correct? Guess what happens to 'pitch' in a vacuum chamber. I've taken pine that was dried to a max of 140'F in a vac chamber and heated pitch pockets to 190 and they stayed solid.

Den

[jimF]

Tom's explaination is the first step to understand what is going on.  But there is a strong interaction beteewn the pure chemicals in the mixture.  The remaining mixture will melt and flow at a temperature lower than the maximum temperature at which it was previously exposed to.

When it is exposed to the maximum temperature also influences how effective the "setting" process is.  If performed early in the drying cycle(when the MC is high) it is more effective than later (when the MC is low) because water is part of the mixture and it's boiling point also influences the boiling point of the mixture.