Definition
Bronzer base, also called cosmetic guide colour, is the temporary tint added to a self tan so you can see where you’ve applied product before the real colour develops.
why it matters.
Without a guide colour, application is guesswork. The bronzer rinses off in the first shower, leaving the real DHA-developed tan underneath. If your tan looks paler after the first shower, that’s the bronzer leaving — not the tan fading.