On 15/12/15 21:03, Ed Huntress wrote:
On Tue, 15 Dec 2015 14:48:33 -0600, "Terry Coombs"
wrote:

Jon Elson wrote:
Terry Coombs wrote:


I don't have a pottery supply near , but I do have a large pile of
fiberglass batts . You think they'll work at the temps you use ? The
grates aren't so awkward in shape , I plan to build an enclosure with
firebricks and preheat with my foundry burner . Heat 'em both up and
let one soak while I weld on the other , swap as they cool .

No, you can melt fiberglass on a kitchen stove. I don't know what
the glass type is, but really low melting point.

Jon
THanks , looks like I'll be inventorying the fire bricks . I've got enough ,
just gotta dig 'em out of storage .
I guess you know to heat and dry them slowly if they got damp. I keep
mine in a big plastic bag (3 mil) made for collecting trash on
construction sites. They can crack, and even explode, if you heat them
when they're really damp or wet.

Glass wool melts at around 1,000 deg. F. If they use Johns Manville
Mineral Wool for insulation in your area, that melts at around 2,000
F. Other kinds of "rock wool" and "mineral wool" vary all over the
map. The old stuff was made from steel mill slag, but they make it
from a variety of things today.

You shouldn't heat your iron above 1,200 F. It goes hot-short at
around 1,400 F or just over, and it will crack if you look at it
cross-eyed at that temperature. Lincoln Electric says to pre-heat in
the range of 500 - 1,200 deg. F.

http://www.lincolnelectric.com/en-us...on-detail.aspx

Good point on the fire brick if dense fire brick but if insulating fire
brick it's so porous I can't see it being an issue as it would just
vent steam when heated. If I need to make a temporary hearth I have
quite a few 2300F and 2600F classification temperature IFB.