I have a brand new exterior fiberglass door with a poly finish. I want to change the color. Do I need to sand or otherwise rough up the surface first? I have been told by the manufacturer not to sand it. How can I change the color?
Do not sand, this could ruin the door. Use a liquid sander like Paso to clean and degloss the surface.
The color can be changed by restaining with a gel stain and applying another clear coat after the stain has dried.
This only works if a darker color is wanted. If you want an entirely new lighter color then the original stain has to be stripped before restaining.