The other option is to add your colour to a small amount of water, add your other liquids to the dye water and mix, then add to your dry ingredients and mix as you would normally.
-These are concentrated dyes so it is best to always wear gloves as particles spread easily.
– Water soluble dyes do not normally stain bathtubs unless the bathtub is lacking enamel, painted, or is scratched/coating worn off. Even then it is rare and usually too much color has been used. We have a painted bathtub that stains easily. It takes a lot of dc red 28 to stain our tub. If colours are used in reasonable amounts there should be no issues. This is also why we use poly 80 ourselves. This ensures no dye gets stuck in the oils and stick to the tub. If this happens a little bleach spray and a warm wet cloth should clear this up.
-Most dyes are light and UV sensitive. Some will fade in sunlight/UV light.
FD&C Yellow 5