[Coloring slip]

Thanks for your quick response!!! Any guess how much food coloring I should add? I have a tote of slip that's about 150 gallons.... maybe a  pint or 2 should do the trick? Crazy question, I know. 

[Coloring slip]

I use 2 different slips in my studio, now that the low fire is made without talc it is very hard to tell the difference between the 2! I'm looking for ideas on how to possibly color the slip slightly so it looks different than the mid fire, but nothing drastic. Any ideas? Should I just use a brown or gray stain?