annealing steel

[jlrussell4]

I've got some hardened steel I would like to anneal. It seems that the medium of choice to place the hot steel into to cool slowly is vermiculite. My local Always Charge Extra store says they cannot get it any longer. I checked in Lowes garden center - no luck here either. Someone mentioned sta-dri (kitty litter) once. Does this hold heat long enough to work? Any other suggestions including where to look for vermiculite?

Thanks in advance

[shortbus]

How about here? http://www.vermiculite.com/ A lot of information and where to buy.

cary

[Gene_Olson]

The old standard was always wood ashes.

Vermiculite is basically "pop corn" except it is popped Mica (or close variant) hence your problems with finding it. It was made in NE Mpls for one place at least. Some of the Mica used there had asbestos in it. Most of the really BAD* asbestos came from one mine in Montana, unfortunately that mine was one of the suppliers for the Mpls factory. There is continuing litigation over high cancer rates in people who played near the factory and in it's piles of mineral.

(*for example there is an area in northern california where a vein of asbestos is at or near ground level. all rock cuts cross it. the streams eat it, the wind blows it. it is a huge component of basic road dust, yet the cancer rates are only marginally higher than the rest of the state.)

What you cool it in depends on the alloy. Some need to cool real slow, ie they need an oven. If that is the case, maybe make friends with a glass blower, they have slow cool ovens for their glass.

[James(Western Canada)]

Jim: A friend of mine was the shop foreman at a welding/machining/fab shop for a number of years, and they had a box of ashes under the stairs to the mezzanine that was used for such things.....the only bad news is I cannot tell you exactly what type of ashes they were.....but I know that items placed in there one day would still be slightly warm to the touch the next day, so it was certainly insulating well

James

[jlrussell4]

Thanks guys, I never would have thought of ashes.

[oldgoaly]

Coal ash "clinkers" was very common. and I have an old metal pot filled with sand, it gets heated in the oven, also a kiln would work, they hold the heat, cool slowly. I mainly use the heat treat/muffle furnace for annealing small stuff. tt

[edthomas]

A local old timer near me turned me on to burying steel in sand. About 3 or 4 inches over item works pretty good, seems to hold the heat for quite a while. Might be worth a try

[jlrussell4]

Ed & Terry,

One thing I have a lot of is sand down here. Lots of good cheap choices.

Thanks

[Ron Naida]

A while back we used vermiculite mixed with portland cement for
vinyl liner pool bottoms.
A pool supply house may have it but the bags were about as big as pine bark mulch bags. you might find some ripped open ones cheap.

ron

[larry mullen]

Jim
An old timer i once knew used lime to slowly cool engine blocks from model Ts after repair welding .
Larry Mullen