From Ardex Butynol specification:
CLEANING WEATHERED BUTYNOL
Use sugar soap to remove oxidation and restore surface.
PAINTING OVER BUTYNOL
Use Roof Acrylic paint with Ardex Seam Primer on non
ponding areas. Wash with Sugar Soap. Beware of using
non Ardex primers as this may effect your Butynol
Warranty.
N.B. If flashing tape is used it MUST NOT be left exposed.
A cover strip of Butynol must be applied over
the flashing tape to finish.