Do you have to put a finsih on an exterior fiberglass door

I believe it depends on the door. From what I understand the expensive fiberglass doors that resemble wood do not need a finish. I think I read somewhere that the plain white doors need to be painted otherwise that might get a yellow tint. I've had my front door unpainted for 2 years and there hasn't been any yellowing.

Many good fiber glass doors will have instruction on how they can take a stain and/or paint