Bill Tindall
Heat, other than its effect on drying rate and humidity will have no effect on either color or stability, the two issues most often rationalized for air dried lumber. I have never seen a study exploring whether wood dried at120 degrees differs in properties from wood dried at 150 degrees. I suspect there is no significant difference just from the fact that nobody in the industry seems to fret about the final kiln temperature. Other than the impact on cost of operating the kiln I have never heard temperature discussed. The only specification is per cent moisture. If it is 7% or less factories turn it successfully into products and so can individuals.

I know of no chemical basis for the concept of heat "setting" the lignin. The main effect of drying is the collapse of the wood cells and the volatilization of resins and the like.

For wood that has a high concentration of volatiles, for example pine, kiln temperature affects whether the remaining resin is hard or sticky. Wood dried at a very high temperature, higher than any commercial kiln operates, does change physical properties.