I dont know what they had high concentration hydrogen peroxide for. Never messed with it during class, just got to see some cool stuff after class. The teacher was a old redneck guy with a MB 300TD that is all beat to crap converted to run on veggie oil lol I would say about 2-3 seconds and you could see flames on the pile of sawdust, but it started smoldering immediately. I bet higher concentrations would decompose and create heat much faster. Grades used in rocket fuel decompose at an explosive rate.