Question about annealing using wood ash

[Countryboy39067]

Does anyone know how much ash is required to anneal a blade properly. I plan to make a box to anneal my blades in but I want to make it big enough for swords later. My question is simply is there a length to ash ratio that tells how many inches of ash a blade is required to be suspended in to anneal properly. Thanks for reading this.

[reefera4m]

Does anyone know how much ash is required to anneal a blade properly. I plan to make a box to anneal my blades in but I want to make it big enough for swords later. My question is simply is there a length to ash ratio that tells how many inches of ash a blade is required to be suspended in to anneal properly. Thanks for reading this.

The purpose of the ash is to insulate the hot steel and allow it to cool as slowly as possible. The more 'insulation' the slower the cooling. Some 'experts' recommend cooling at a rate of 50 degrees/hour when using a kiln with 'step-down' process capability. I've found that using a 12" layer of wood ash surrounding the steel will slow the cooling down to between 8-12 hours, usually overnight. This seems to be sufficient when I anneal 5160. I keep a large (35 gal) garbage can full of dry wood ash and place whatever steel I,mtrying to anneal into the center of the can, surrounded by at least 12" of ash.

I've been using more vermiculite recently since I found some at Lowes ($23/3.5 cubic feet). It's less messy and seems easier to keep dry. Vermiculite also doesn't leave any residue on the steel like wood ash sometimes does.

[ThomasPowers]

I'd also suggest going with a steel garbage can or even 55 gallon drum. Ash is quite cheap if you heat with wood! Sift out the charcoal and save that for forging with.

[pkrankow]

I have a 5 gallon steel lidded ash pail full of fireplace ash, and that seems adequate to anneal 8 inches of coil spring. Only about 2 inches on the ends, and 4-6 inches elsewhere. Still WAY hot after 4 hours, rather warm after 24 (about 120F).

Phil

[Countryboy39067]

Thanks guys! My idea was using a 55gal drum cut in half. Use one as a ash pot and the other as a slag tub. I figure I'll be annealing a few things at one time and that would keep the temp from dropping too rapidly. I have a few drums from a friend that races stock cars that I can convert to smithy tools. Of course I'll fill them with water to eliminate the BOOM factor before I cut them. Thanks again guys! This forum is getting me leaps and bounds further than I ever imagined.

[BIGGUNDOCTOR]

If you cut the drum in half the short way it is easier to put a lid on it,as opposed to the long way. Also easier to move by rolling on edge.

Depending on what was in the drum, filling with water may not keep the booms away. You need some air gap in order to cut with a torch, that gap can trap fumes. A mechanical method like a recip saw may be a better choice. When I was welding automotive gas tanks, I would fill them part way with water then purge with Co2 to flush any remaning oxygen out.

Be safe.