Hum, I've done the 250F for 30 min. Not bad. The idea here is to degrade the plant material on a molecular level, removing the acid molecule(s) on several chemicals. Over time, this is a natural process, i.e. time, temp, sunlight, humidity, etc. We wish to speed the process. But why are we in such a hurry?
Making tincture will take time. Caps or butter take time. Again, what's the rush?
The last two batches I ran at 220F for 1hr 45min. You've no doubt heard the term Golden Dragon? Yeah, it was like that after a 30 minute soak. Best tincture yet. I hope to experiment with several different times/temps this harvest season.