firebrickforge from Zoeller Forge - October 29, 2008:  &quot;The forge above is basically the same as the first firebrick forge that I built except this one has a layer of 3/4&quot; 3000°F  42% Alumina Firebricks on the bottom.  This forge has a more durable floor that can also be used for forge welding.  I put the two interior floor bricks together using Derby 3000 °F Mortar.  This will keep the flux from running down in between the bricks.&quot;