You can add color to almost any material by using a color tint or pigment. Not all pigments are compatible with all materials.
For example, you want to use urethane tints (such as SO Strong Color Tints) with urethanes only. Hint; anything that tints urethane paint will tint a urethane rubber or plastic system.
Color silicones with silicone pigments only (use only Silc Pig silicone color pigments). Using incompatible coloring systems may result in the rubber or plastic not curing.Avoid powder pigments, as they may be hard to disperse and may cause a moisture reaction in urethanes. Start with small percentages of tint or pigment; you can always add more.
Thoroughly pre-mix tint or pigment with Part A or B before adding.