Paint adherence on fiberglass door. Does it need time to 'cure'? Can I top-coat it?

Question

We bought this door:

http://www.homedepot.com/p/Feather-River-Doors-6-Lite-Clear-Craftsman-Unfinished-Smooth-Fiberglass-Prehung-Front-Door-GK3191/204487447?N=5yc1vZas82Z7cm

I've primed it using Zinsser and then gave it 2 coats of Behr Marquee Exterior.

Looks great. Alas, 24 hours later, I can take my fingernail and scrape of the paint.

It's been a bit humid/rainy. Do I just need to give it more time for the paint to fully harden? Or did I do something wrong with this fiberglass door?

UPDATE:

Another day and the problem remains. I can confirm it's the paint. The paint can be scraped off with a fingernail, but the primer stays.

I'll give it another day or so (it's been humid) and hopefully it fully 'cures'. But if not, do I have options short of stripping the entire door? Is there any sort of top-coat I could apply to give it a stronger surface?

Ben · Answer

I have lots of questions!

Is the door installed in place?  If so, is there a storm or screen door?
Did you paint both inside and outside surfaces? If so: Did you use the same paint on both?  Are they both experiencing the same problems?

If there is a glass storm/screen door in front of the door, this could lead to problems with paint on the outside where the paint is trapped between the door and the glass.  If you could answer these questions in your question or as a comment, I can provide a more targeted response.

This paint has a 4 week cure time and should will take longer to set if applied in higher than 60-70% humidity.

For expert advice, you may consult with a BEHR Certified Coatings Professional, call 1-800-854-0133 Ext. 2 in the US.

harvey · Answer

Paint pealing off is usually a sign that you have layered an oil based paint over a water based paint or primer. A good sign that this has happened is if it peels of in strips.

Your paint may also have gone bad before you bought it, if it was not properly stored for instance, it may alternatively have been mixed with the wrong dyes (using an oil based dye on water based paints can do this), and various other reasons. If the paint is chalky, or just scrapes off than this may be the case.

You can strengthen a a layer of bad paint by using a peel stop and strengthening product such as Zinsser Peel Stop. This may solve your problem.

Clay · Answer

I am a painting contractor. Do not try to scrape anything off with your fingernail until it is fully cured. This is something all the wannabe or new painting contractors run into...and they are so naive they want to blame somebody before the paint is even cured.

Answered by Clay on September 28, 2021

Baritt Neeman · Answer

This is my experience with fiberglass painting and staining;
I work for Epic Doors which manufactures high-performance fiberglass entry doors.  We evaluated several paint suppliers including TruCoat 623, Sherwin Williams Polane 2K Acrylic, and Aquasurtech D200.
We were looking for an environmentally friendly, single component water based paint that was super durable, had great adhesion and laid down smooth.  Based upon our evaluation we selected TruCoat 623.
It was much more environmentally friendly than Polane 2K and is a single component and TruCoat had better adhesion than D200 and was priced better.

Paint adherence on fiberglass door. Does it need time to 'cure'? Can I top-coat it?

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