Document QgOOBVjYJRb9zgyK031mq7OXv

May 7, 1970 R.M. Specification No. 11 Page 2 25 grams of mica are weighed into an 800 cc. or 1000 cc. beaker, the latter being preferred. Water is run into the beaker with sufficient force to thoroughly agitate. Let stand for 15 seconds and carefully decant about 2/3 of the liquid, being sure not to lose any grit. Repeat washing and decanting until most of the mica has been removed and then nearly all of the water should be poured off each time. Washing and decanting should be continued until the water is substantially clear at the end of the 15 second settling period. Then let the beaker stand until the solids have entirely settled and then carefully decant most of the water. Dry beaker and contencs, loosen the solids from the beaker with a small brush and transfer to a scale and weigh. Weight in grams times A equals % grit. The grit should then be screened thru a 30 and 50 mesh screen. All grit must pass thru the 50 mesh screen to be icceptable. What is desir d is a grit free mica, and at any rate, the maximum amount should not exceed 1% and none of which should be retained on a 50 .iesh screen and preferably none on a 100 mesh screen. SAMPLING Representative samples shall be taken from each shipment and tested for the above. If the shipment does not come within the specifications, a laboratory batch of Finisher shall be made and tested. If this finisher is off-standard and complaints may be anticipated, the mica shall not be used. A sample of the mica shall then be sent to the General Laboratory with full particulars. EDO:dek SGP 0015935