chemicals only kill wood worm on entry or exit , freezing does not kill lower forms of life but puts it into suspended
animation ( sperm eggs ) microwaves have trouble penetrating to the centre of thick wood it would take a long time of
on off work to the inside hot without cracking the outside. The best suggestion is to get a dustbin and wallpaper
stripper ( steam ) wrap the wood in a wet towel then a bin bag you can leave it in 1hour per inch thick.
remove bin bag and leave to cool before opening " TACK CARE IT IS VERY HOT."
Tony