Hmmm, I guess that it is a little on the dangerous side if the gasses created by the transformation of ethanol above 400 deg. C are flammable (H2, CO, ect.).
Thanks technocrat for the breakdown- it answers the question as I was not concerned about methanol vapor but the byproduct of the gasses.
rcoope, unless it is a very small oven then it can be dangerous- I agree. I also agree that you would have to use something with atmospheric control on something bigger.
So bear with me and tell me if I'm wrong but...:
As I see it, the major hazard is not the vapor ethanol but the byproducts of the new gases formed during the transformation which would outweigh the ethanol percentage in the kiln/oven enormously.
So on a normal kiln, if you wanted to do a quenching on parts, as soon as you open the door, introducing oxygen, then the chamber would probably ignite because of auto ignition. Auto ignition of say, H2, is 585°C and 609 deg. C for CO. Stoichiometry percentages are probably irrelevant because at some point on opening the door, there will be a ratio that will burn and there will be a hotspot in the kiln well above auto ignition temperature. I guess it would be technically safer to temper parts and leave the door closed but still potentially very dangerous.
Thanks all for the replies- much appreciated. It is good to know why not to do something as opposed to "just don't do it".