I used both natural and "coffee" 'boo flooring and anecdotally believe the 'coffee' has already been heat treated over and above the natural. I also "believe' the coffee presented a slightly better performing bow. but don't have any chrono figures to substantiate this.On another note I have to almost curtail my bow building after an almighty health scare. I hope to still make the occasional on,perhaps more self bows. Years of working without dust extraction, only a particle mask may have left me compromised.all my tests have returned negative but some symptoms persist. So guys really look after yourself , in the end the only thing we all really need is our health.