The LOI on borate materials is difficult to measure because they have mechanical and crystal water and the temperature to heat samples to to remove only the former is difficult to assess.
Thus, the test is done this way:
-Take ten samples (from 10 bags) and mix well
-Weigh a bisque-fired bowl and dry and mark the weight on it
-Put powder straight from the bag into the bowl, weigh and mark
-Fire to cone 04
-Weight again and calculate the LOI
This calculates the LOI as follows:
Bowl - B
Bowl+Powder - BP
Bowl Fired - BF
(BP-B) - (BF-B) / (BP-B) * 100
This is the weight of the powder. The powder should be from a sample that has been collected from at least 10 bags throughout the shipment.FWT - Fired Weight (V)
The weight of the powder fired to cone 010.
Test conducted primarily on materials use to make bodies or glazes.