hi martin,
the thermal process that has been street named "roasting", is done to wood that has already been kiln dried to the 6-8% that is industry standard.
during the process, the wood is heated to about 100C, then virtually all the moisture is extracted from the wood. then the wood is heated further until it reaches 185C. at this temp the sugars in the wood change and are gone along with other elements in the wood. the wood is then rehydrated back to it's 4-7% moisture content.
because the cell structure of the wood is changed, it takes more time taking on, or losing moisture, making it more stable in varying weather conditions.
it is a very precise and controlled process, not just putting wood in an oven and drying it out. wood can be destroyed if it is not handled correctly. not all species react well to it.
i hope that helps.
tom
Tom Anderson
Tom Anderson Guitarworks