Im 21, automotive tech, body/paint man by trade, woodworking as a hobby, i enjoy metal work as well, im excited to get going with knifemaking. My questions to you, have probably been addressed, so forgive me. Ive made a simple forge, using a steel pre-heating propane torch, running into a small brick forge. Im doing it all outside, what are the risk factors of an explosion or fire here? Im no fool, but i have limited time dealing with propane, just dont want to have any bad times with that. Second question is regarding my insulation, ceramic fiber board, will it emit toxic fumes in which i need a respirator? Or being outside should i be okay? I know some risk must be involved but how great? I wear a respirator at work, sometimes all week in a paint booth, it isnt exactly wonderful, being 95° out. So if i can avoid it, i would like that. Thanks in advanced for my rookie questions. 

Hand torches simply aren't designed for, and don't belong inside of heating equipment. You'll be far better off building or buying an air-fuel burner; that said plenty of guys have got away with using jewelers torches that way; I just don't recommend it, because plenty of guys get away with plenty of things--until sum guy doesn't...

 

How great a risk usually depends on length of exposure more than amount of it. The social battle over Industrial contamination started being fought here in the sixties, and  biased information was generated by both sides. I was chair of the Boiler Makers local #104 safety committee, and witnessed a lot of "down and dirty" tricks. But the strongest fact that I took away from that experience was that health studies can't help generating flawed statistics over time, because most guys  are just passing through the trades these days, while bad health impact shows up strongest in guys who spend their careers in a single trade.

All this to say that low levels of exposure all have an effect; how dramatic usually depends on how long you're exposed, but anyone can "roll snake eyes." You are 21 now, but someday you'll be 61; it's a little late to be careful then...

Ceramic board is simply super compressed ceramic blanket. Once either product hits 1600 F it will start forming crystabolite; a known carcinogen. However there are many inexpensive sealants, such as Satanite, which stop ceramic particles from becoming airborne. 

Tho I agree with Mike on all points (and building a gas burner is cheaper than most good torches) the usual method of using a plummets or keepers torch in a 1&2 brick forge or a soup can forge is to aim it at a hole in the side (inch or two gap), not put it in the hole. Putting it in the hole leads to melty issues with a  tube pumping flammable gas into a hot can.

as Frosty, Wane and Mike are all very forthcoming with burner building info I'd be tempted to go that way with a small gas forge. 

Myself, a cheap bed inflator (the big pool inflators are on clearance at my local Wally World for $13) and a 3/4" valve and a peice of 3/4" pipe and a box of dirt gets you off and running. 

You are right, Charles:

Unfortunately, it doesn't take people long to figure out how inefficient that positioning is, and they are inevitably tempted to push the torch tip part way into the hole. A workable compromise would be to add a burner holding exterior pipe with a rotating choke, so that secondary air can be controlled; best of both worlds, but don't hold your breath waiting for people to do it

For the small tinkering I'll stick to charcoal, lol. 

BTW, charles,

One of my favorite contributors on a casting group is into jewelry work and uses his jewelers torch to power a miniature casting furnace. I'm trying to provoke him into countering my argument, because this is  an issue I'd rather lose than win--so long as it can be done safely

Lol, that's a rare man to admit such a sentiment 

Too soon we gets old; too late we gets smart. Better late than never.