Subject: [TheForge] Strengthening castable refractory

[Thomas A. Troszak]

> From: Marc Godbout <marc@ironringforge.com>
> Date: 21 Aug 2003 22:17:02 -0500
> Subject: [TheForge] Strengthening castable refractory
>I'm building a new forge. This one will have an arched roof made out of
> insulating castable refractory. The insulation will be in a metal shell
> - a half-pipe. Is there anything I could, or even should, do to
> strengthen it? 

Dear Marc,

The people who sell the refractory should be able to supply you with
stainless steel "needles" for reinforcement, they are usually 4-5 dollars
per pound. Add 1-2 pounds of needles per bag (50-80 lbs.) of refractory to
the dry mix, and you are good to go. They make the resulting refractory
tough like straw in bricks.

I have used insulating castable refractory (reinforced with stainless
needles) to cast furnace roofs that span as wide as 4 x 6 feet, in a flat
slab, suspended from a steel frame by floating stainless J hooks cast into
the slab. Works great.

The most important crack prevention is to simply mix the refractory using
the absolute minimum water necessary, and cure it well at low temp. before
firing.

Tom Troszak