Hi,

My problem is with a fiberglass front door and I am only painting the sides and the inside since HOA is responsible for the exterior (I think, haven't check that out).

I chemically stripped the old paint to the bare fiberglass,
-apply mineral spirits, let dry,
-scrapped/sanded dried left over CitriStrip,
-washed with TSP substitute and went over twice with damp rags to rinse,
-apply mineral spirits again,
-sanded with 220 grit lightly,
-apply with denatured alcohol or 91% rubbing alcohol,
-and then primed the raised panels, and let dry overnight.

I primed with a never opened old can of Zinsser 123 primer. I am in Hawaii so the temperature is in the high 70's or more and there is a nice cool breeze where I am and humidity is high. I am painting it mounted on the hinges.

I was going to prime the rest of the fiberglass door. Then I decided to test and was able to scrape off some of the primer with my fingernails, but not all of the primer. The edges where the primer was thick and I may not have sanded it well. The area with a light coat of primer seems to adhere better.

The primer on the trim and door jamb seems to adhere correctly.

Now, it is two days since I primed and I can still scrapped off some primer with my fingernail. It seems that in Hawaii, I need to wait overnight to recoat, even though the instruction on the can say you can recoat in 1 hour. Must be the humidity.

I did a google search and some forum suggest using some kind of bonding primer. I am hoping not to buy anymore primer.

I am planning to sand again more thoroughly with 100 or 220 grit and then prime again. I plan to do two coats of primer and let dry overnight and then two coats of semi-gloss off white as topcoats.

Please let me know if you have a better suggestion.

Thank you very much for your time and help.

 

Follow-up question:

I am considering buying a better primer and apply it after sanding some more. For a fiberglass door, what is better Zinsser Peel Stop or SW Multi.

 

On a fiberglass door, SW PrimeRx Bonding primer would have been best. You want to lightly sand with a fine sanding sponge after you prime, just to remove impurities, then dust the surface before painting. I would not use 123 on a doghouse. Almost any primer will scratch off of fiberglass if you scratch hard enough, you just don't want it to scratch easily.

If it's already been primed, putting more primer over it is a waste of time. You should either strip it, or keep going.

You should also usually follow the finishing directions provided by your door mfg.

I just finished painting a new fiberglass door today and got it hung back up.

 

Thanks for the reply.

The door came with the house when we bought it so I don't know the manufacturer.

The SW store near me may not have the SW PrimeRx Primer, I only asked about Zinsser Peel Stop and he didn't have that but have the SW Multi.

I opted to buy Zinsser Peel Stop from another paint store and the man told me that in my area, people use the Peel Stop and then a primer and then topcoats.

So, I am going to sand off the 123 primer and scuff the fiberglass door one more time more carefully with 100 grit and then apply the Peel Stop, let dry overnight, apply 123 Primer, let dry overnight, and then two topcoats.

That's my plan for now.

Please let me know if you all have other suggestions and thank you.

 

While I've painted a lot of doors, I've only painted a handful of fiberglass doors. I kind of think you are expecting too much out of the primer. Primers don't dry as hard as paints and most latex coatings don't develop to their hardest until for a week or more.

Your plan sounds ok, just be sure to remove any sanding dust between coats.

 

Thank you for your reply.

I only repainted the door since it was stripping and flaking. I have never prepared any door like this one before and didn't want it the paint to peel anymore.

I apply the Peel Stop and will put down 123 primer over that.

Thanks.

 

Hi,

I am reporting back.

Finished according to my plan and it turned out good.

I did NOT test my work with my fingernails and will see how long this will last.

The Peel Stop was very light but applying primer or paint over that was not easy. You have a limited time like less than a minute to put on your primer or paint. You could not rework it more than three times, meaning I was not able to brush over or back and forth as the primer or paint would come off. It was best to brush it once or twice and wait until dry if you wanted to put more coats of primer or paint.

Once my primer was on, it was easier to put on the topcoat and to me it was hard to keep a wet edge unless I painted the panels and groves, let dry, and then the horizontal and vertical stiles.

I actually put on three topcoats.

Thank you for your help and time.

 

Was the door hot or in the direct sun?

 

No, I was painting the inside part of the door and was painting at night. The temperature was hot and humid overall.

This was the same experience I got painting Peel Stop and then a 123 Primer on window sills and one bathroom door; they were also peeling.

Thank you and blessings to all.