FIREBRICKS SP-85% Alumina (2900-3200°F) - ULTRA DUTY - 9" x 4.5" x 2.5"

These are overkill for general refractory projects.  With 85% Alumina, these SP-85 Bricks are designed for heavy abrasion and hard service.

Features:

• Stronger and Heavier than even Super-Duty Bricks.
  
• Cold crush strength of 15600 psi at 70°F

Sometimes I like using thin slices of these bricks as a wear plate or where abrasion protection is needed without needing the full brick thickness.

Note that while strong, Dense Firebricks are heavy.  While they are a great heat reservoir, they can also take a lot of energy and time to get hot.  This is an important consideration in designing a forge, furnace, or oven.  The classic ovens that run 24 x 7 do great with the thermal mass, but for faster heat and recovery times in a small forge, lighter insulating firebricks (IFBs) are almost as efficient as wool at insulating.

Note - there is still enough porosity in these bricks to allow reflective coatings like ITC100 to be applied on the fireside of the brick to help reflect heat into the firebox.