I am getting ready to do some colorant tests using different concentrations. My approach in the past has been to just wing it and add as much as I think looks good. But, I am hoping to change my haphazard ways and am trying to create reproducible results with oxides, ultramarines, and other colorants. I can’t find a resource that uses colorants by weight - all are by volume and generally the starting point is 1 teaspoon ppo for micas and 1/2 teaspoon ppo for oxides. I know that the amount of colorant by volume is likely to vary based on how “fluffy” the colorant is. I could also measure a teaspoon of a colorant and then see how many grams it would be. Does anyone measure colorants by weight or know of a good reference that does so? Thanks in advance.