What will interfere with PURETi doing its job?

Painting over PURETi will block the light and stop the photocatalytic process (photocatalysis). Similarly, applying wax over PURETi will block the moisture need to activate photocatalysis. Gum, bird droppings and other large masses of light blocking matter will also limit PURETi’s functionality.

Since normal household paint is many times thicker than PURETi, the PURETi layer can readily be painted over if the homeowner wants to change the color of PURETi-treated siding.