[TheForge] Kaowool vs Soft Fire Brick

[Bruce .]

I don't think you need BOTH satanite AND ITC-100.  You might want to look
into that.

I believe data is available on-line that shows that mineral wool (Kaowool,
for example) is a significantly better insulator than is soft firebrick.
My limited experence with these supports this.

You will need something firm on the bottom of the forge to support the
weight of your workpieces.  And you probably will want something resistant
to flux, which neither Kaowool nor soft firebrick are. As someone else
suggested, a hard firebrick works.

Alternatively, support a "kiln shelf" (which is like a thin, hard
firebrick) on several pieces of hard firebrick, and surround the supporting
pieces with Kaowool.  \

Another alternative is to use soft firebrick on the bottom, but put a thin
piece of SS sheet on top to resist the flux -- I've had some luck with
that.  (Think: old SS cookie sheet.)

One thing about using Kaowool (at least without Satanite or ITC-100) -- It
must be a single piece in an arch from one side of the bottom firebrick to
the other, lest it collapse.  If you use two layeres (e.g., two layers of
1" thick to give you the needed 2" of insulation), you must use two such
arches, one inside the other.  Cut the lengths a little (~1"?) longer than
"theoretical" so that the Kaowool compresses along its length slightly as
it's installed.  Once fired, these arches are stable, if not abused.  Other
arrangements may collapse.

Finally, if you have no experience using gas forges, consider seriously the
size.  A gas forge heats everything inside it to forging heat.  A coal
forge, by contrast, affords much more "spot heating" control.  If you're
going to want to heat no more than 4" at a time, you may need a forge 4"
long ... with a hole in the back for the workpiece to protrude thru.

Bruce
NJ

On Wed, Aug 17, 2016 at 7:58 PM, Daniel Kretchmar <dan at irontreeworks.com>
wrote:

> I have questions for the hivemind:
>
> I wish to build a new forced air forge.  My current plan is (starting from
> the outside)
> 1. A shell from a 40 lb propane tank
> 2. A layer of fitted soft brick with high temp mortar or a layer of kaowool
> 3. satanite
> 4. Itc-100
>
> Questions: Will softbrick insulate as well as kaowool?  Will soft brick be
> more durable when using borax for flux or will it melt just as easily?
>
> Suggestions are appreciated.
>
> Danr
> www.,irontreeworks.com
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