Answer:

Boric acid is the hydrated form (it contains water) of boric oxide (anhydrous form or free water).

Boric acid H3BO3 at low temperature (less than 150 ºC) decomposes to boric oxide (B2O3) and water (H2O) representing approximately 44 % by weight.

This means that when we have 10kg of boric acid in a lining it will decompose releasing 4,4kg of water. This fact should be taken into account when the suitable percentage and the definition of the curve of sintered are chosen.

From the point of view of thermal behaviour the major dispersion of boric acid makes that the lining presents a better light mechanical resistance than the similar percentage in boric oxide.