Help with Paint on Fiberglass Front door
I recently installed and painted a new Jeld Web smooth fiberglass door unit. I painted the door before hanging and the job was perfect before the door was hung. Now that the door is up, I am getting small pimples or bubbles around the inlaid areas on the door.
The details:
Primed with oil based primer tinted medium brown. Topcoat is 100% Acrylic Valspar tinted a cranberry / maroon color. I went with brown primer due to the red topcoat.
The top half of the door has no problems, only the bottom half which receives morning sun. The bubbles are tiny and have appeared since hanging the door. When I try to scrape them with my fingernail, they don’t easily scrape out. I also tried sanding a small area and they don’t easily sand out either.
I guess what I’m trying to determine is if my method or prep is the problem or if something else (like the sun exposure) is the problem. I plan to pull the door, strip it and repaint, but need to ID the problem first.
Any thoughts?
Replies
I recently had this problem with my Therma-tru door. I cleaned, primed with Sherwin Williams A-100 and top coated with Superpaint. I noticed little blisters after about a week.
I talked to counter guy at Sherwin Williams and he said he has seen this before and recommended a bonding primer.
I stripped the door, cleaned, reprimed and top coated with Superpaint. It has been 2 months now and it looks perfect.
Good luck.
Is your door FG? What did you use to strip it? I want to strip rather than sand and need something that won't damage the FG.
Thanks for the advice. Based on your experience, and the advice of the counter guy at SW, I:1) Stripped the door2) Primed with SW "Bonding Primer", that's the actual name of it and it is the only primer they sell that is indicated for FG. The counter guy said it's pretty tenacious stuff.3) Will topcoat with Superpaint exterior paint after the primer dries. Hopefully that's my ticket. For the person that was wondering earlier what the difference between "primer" and "bonding primer" is, I don't know the answer. But SW has a bunch of primers- the only one they recommend for FG is called "bonding primer", presumably it is better at bonding paint to slick surfaces. I suppose time will tell. It is nicer to use than any Kilz or Bullseye I've ever used though.
For the person that was wondering earlier what the difference between "primer" and "bonding primer" is...
That was me. Thanks for looking into it. Even though we don't have a definitive answer, Here's how I think: if "bonding primer" is more tenacious than "primer", why wouldn't I always use a bonding primer? Maybe it's a simple matter of price. I'll annoy the Sherwin Williams people with the same question the next time I'm there.
"Maybe it's a matter of price".Could be, I paid $16.49 for a Quart of the stuff! But with the headache of this door, and the trouble I went to the first time, only to have to strip and redo, I was happy to hand him the $$.I did wonder though- what's the difference between the primers.
A primer is a coating designed to prepare a surface for finish coating. Depending on the qualities of the substrate a primer can perform functions such as
reducing absorption of finish coat vehicles into the surface, which would harm the formation of a durable finish film
reducing roughness
converting surface oxides into substances to which finish coats would better adhere
hiding color variations
evening out the gloss of finish coats
consolidating old chalky paint into a solid base
When painting over surfaces such as water stained wood or knotted wood, substances in the wood can bleed through standard primers. Primers designed with the added feature of sealing against such bleed-prone stains are called primer-sealers.
Primers specifically designed to adhere to surfaces difficult to adhere to, such as fiberglass, plastic, or high gloss paint, are called bonding primers.
I have used a lot of SW PrepRite "plain" primer. It is a basic universal primer. It seems to be the same as Bullseye 1-2-3.I have also used SW PrepRite Bonding Primer when painting over varnished trim. It is much the same going on, but it builds up on the brush and it much harder to wash out.They also sell a bonding primer (might not be in all areas) by a company by the name of Zim, Xim, Xime, or something like that. I have used that on some AL gutters that the previous coat has had pealed off. It was a while ago and I don't remember that it is dried quickly on the brush like the PrepRite.Yes it is XIM. I believe that it was their UMA primer.http://www.ximbonder.com/products.asp?id=35.
William the Geezer, the sequel to Billy the Kid - Shoe
This is a guess. Oil based primer takes quite a long time to completely outgas. On a porous substrate, wood for instance, the vapors can diffuse through the substrate. On a nonporous substrate, they have to go out through the paint film. I believe the blisters could be from vapors from the primer with no way out.
Fiberglass doors have very specific instructions for painting from the door manufacturer. Did you follow them?
No- there were no instructions from the Manufacturer for painting (Other than "the door is pre-primed, top with 100% acrylic latex topcoat" or something to that effect), just for installation. What special things do I need to keep in mind for painting FG?And I really wonder if the sun exposure has anything to do with it, since the top of the door which doesn't get sun is fine. But the bottom which does get AM sun is pimpling.
The instructions seem to support my guess. The manufacturer instructed against oil based primer. I suspect you trapped the solvents from the primer between the plastic and the topcoat. The sun exposure are probably vaporizing the solvents and they have nowhere to go.
Some fiberglass door manufacturers coat their doors with a bonding agent that would be removed by sanding, thus they say specifically to not sand the door.
You may have to contact tech support from the manufacturer to see what can be done now.
"The manufacturer instructed against oil based primer" Not really- The instructions made no mention of primer. I thought some pictures might help. In the meantime, can anyone suggest what to use to strip a fiberglass door without ruining it? Jeld Wed wasn't much help.
Edited 6/18/2009 2:28 pm ET by frontiercc2
go to a automotive paint place,tell em your stripping fiberglass,should be no problem.
i used to use klean strip "aircraft stripper " on vettes. but i don't think you need anything that mean.latex strips easier than car paint.
be sure to read instructions,most need netrualized with soap and water.
YOU ONLY NEED TWO TOOLS IN LIFE - WD-40 AND DUCT TAPE. IF IT DOESN'TMOVE AND SHOULD, USE THE WD-40. IF IT SHOULDN'T MOVE AND DOES, USE THEDUCT TAPE.
Edited 6/18/2009 3:56 pm by alwaysoverbudget
Acetone might strip the paint. You can try some nail polish remover and a scotch-brite pad in an inconspicuous spot to see. If it works, then hardware stores have acetone in quarts. Nail polish remover has oil in it, so it would not be good, probably, to strip the whole door.
The plan is to pull and strip the door this weekend. I imagine if I strip with mineral spirits, I should probably re-prime. This time I will use latex primer and topcoat. Anyone see any flaws in this plan?
i don't think your mineral spirts will cut the paint,but if it does be sure to wash and scrub the door real well to remove any residue.
one problem you might have is the paint filling the "woodgrain" it's tough to get a rough surface completely clean.YOU ONLY NEED TWO TOOLS IN LIFE - WD-40 AND DUCT TAPE. IF IT DOESN'TMOVE AND SHOULD, USE THE WD-40. IF IT SHOULDN'T MOVE AND DOES, USE THEDUCT TAPE.
If not mineral spirits- can you suggest anything else? Denatured Alc maybe? I am leary of damaging the underlying FG. And I'm lucky- it's a smooth finish door- no wood grain.
if your smooth ,half the battle is over with.
being smooth you might try acetone, lacquer thinner etc.
being it's smooth you could also sand it off.
fiberglass is pretty tough,it will take a little abuse from chemicals,just make sure they have off gas before starting to repaint.YOU ONLY NEED TWO TOOLS IN LIFE - WD-40 AND DUCT TAPE. IF IT DOESN'TMOVE AND SHOULD, USE THE WD-40. IF IT SHOULDN'T MOVE AND DOES, USE THEDUCT TAPE.
Depending on how many "bubbles" and how big they are, my first inclination would be to sand them off. Especially since you said it's adhering ok. Just be sure to sand it smooth into the surrounding areas since it doesn't take much texture to telegraph through.
Doors take a beating over time so aiming for perfection may be a pointless exercise.
Denatured alcohol won't strip the paint, but it will soften latex paint and is a good alternative to sanding to ensure a good bite. There is also liquid sandpaper/deglosser which works even better.
My painters latex painted a stain grade Therma Tru fiberglass door. They got it off with Strypeze, I think. Well, they got most of it. The ThermaTru stain took care of the rest.http://www.tvwsolar.com
Now I wish I could give Brother Bill his great thrill
I would set him in chains at the top of the hill
Then send out for some pillars and Cecil B. DeMille
He could die happily ever after"
That is a MESS. Try an autobody shop that does alot of Vettes.
Forget about my suggestion to sand it. I hadn't looked at the pictures yet. Sorry to see you door turned into such a disaster.
I don't know what kind of stripper would be ok to use on fiberglass, but I'm trying to think outside the box here... how much for a new door?
"How much for a new door?" About $600 which is why I opted to go the stripper root at 6AM. It's now 8 and I'm headed to SW to get some advice on primer and topcoat since the stripper removed alot of the factory primer also. I did manage to strip it without damaging the fiberglass though. Overall came off fairly easily using Strypeeze. I just worked in small sections and tried to work quickly so teh stripper wouldn't attack the FG. Still wondering what the original problem was . . .
I'm betting because the fiberglass is impervious (or much less so than wood).http://www.tvwsolar.com
Now I wish I could give Brother Bill his great thrill
I would set him in chains at the top of the hill
Then send out for some pillars and Cecil B. DeMille
He could die happily ever after"
I know I'm showing my cynicism, but what is a "bonding agent" and how is it different than primer. I don't mean the ones applied by the manufacturer. I mean the ones you can buy at the paint store.
There are primers, primer/sealers, sealers, bonding primers and products that claim to do all 3. I usually use all purpose primers, either acrylic or alkyd, but if there are better primers, I'd love to hear about them.
I picked up a quart of STIX waterborne bonding primer upon the recommendation of a local paint store (I was experimenting with painting otherwise unpaintable surfaces such as tile and melamine). I didn't find its performance any better than any other primer.
"Bonding agent" is my term, going from memory of the description by the door manufacturer. Since fiberglass is a plastic (with fibers internal to the material) the paints that contractors or homeowners would typically use will not stick to it. So they apply a clear coating that permits adhesion between latex paint and the fiberglass.
They could rather have specified that the customer use certain bonding primers, but they are providing value by eliminating such need by applying their coating at the factory. Then all the customer needs to do is apply the finish coat.
I suppose the coating could be called a primer of sorts, although I usually think of primer as having some pigment and a consistency of paint. Their coating is clear and permits either staining or painting. Their coating could be a "primer" for all I know, it just doesn't seem like what I call primer.
I work for a fiberglass door manufacturer name Nova Doors and we use a water based product called TruCoat for painting and staining our fiberglass doors. It is made specifically for fiberglass doors so it doesn’t require any special primers, is super durable and lays down really smoothly. You can check it out here - https://trucoat.us/