This is not correct. Three-color gum, like three-color carbon and dye transfer, are subtractive processes. Each of the color layers functions as a filter through which white light must pass, and as it does the color layers "subtract" a portion of the visible spectrum. That is, the final color depends on how much of the visible light is absorbed by the filters, or color layers.


Quote Originally Posted by donbga
Ah, not exactly. Perhaps factory made products are subtractive but tri-color gum is additive.

Don Bryant