I am switching from SS and soda ash to Darvan 811 in my white (talc body) casting slip. I make a batch with 50 lbs. Tenn. ball clay, 50 lbs. Kent. ball clay, 50 lbs. PV clay and 150 lbs. of talc, and about 17 gallons water. How much Darvan 811 do I need and do I dilute it?