Painting an i3's Roof

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alohart

Well-known member
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Nov 1, 2014
Messages
3,235
Location
Honolulu, HI
I would like to paint the roof of our 2021 i3 Galvanic Gold to match its exterior color. BMW of Honolulu sent me to its 2 local BMW-approved body shops so that I could discuss what I want to do and to get cost and scheduling estimates. The first body shop refused to paint the roof claiming that BMW doesn't support painting CFRP. He claimed that the primer, paint, or whatever would damage CFRP over time. Maybe he just wanted the roof of our i3 to delaminate so that he could replace it for $9k! He told me that he had replaced several delaminated i3 roofs.

The second body shop didn't know whether CFRP could be painted but would check. He told me that the roof antenna and roof side trim would need to be removed. I told him that the antenna is bonded to the CFRP and wouldn't likely adhere to paint as strongly. Also, it was fine with me if the roof was painted only to the edges of the rubber side trim. I wanted the antenna and side trim masked and painted around. He told me that they wouldn't offer a warranty if all trim wasn't removed prior to painting. Jeez, these guys must not want the work, or maybe they want to create unnecessary work so that they can charge more.

I'm beginning to favor wrapping rather than painting. Unfortunately, the shop that did a great job wrapping the roof of our 2019 i3 has no more metallic silver vinyl in stock so would have to special order a roll. They charge $200 for a special order plus the installation cost, $650 total, which is pretty expensive for a roof wrap.

Do you know whether CFRP can be painted without damaging it?
 
Maybe with water based lacquer?
I was under the impression, maybe falsely, that auto paints these days are water-based to eliminate the volatile petrochemical solvents in past paints. Anyone know for sure?

I could understand that petrochemical solvents might damage the CFRP clear coat, but that doesn't seem likely for a water-based paint on a roof that is designed to be fine when wet.
 
I would like to paint the roof of our 2021 i3 Galvanic Gold to match its exterior color. BMW of Honolulu sent me to its 2 local BMW-approved body shops so that I could discuss what I want to do and to get cost and scheduling estimates. The first body shop refused to paint the roof claiming that BMW doesn't support painting CFRP. He claimed that the primer, paint, or whatever would damage CFRP over time. Maybe he just wanted the roof of our i3 to delaminate so that he could replace it for $9k! He told me that he had replaced several delaminated i3 roofs.

The second body shop didn't know whether CFRP could be painted but would check. He told me that the roof antenna and roof side trim would need to be removed. I told him that the antenna is bonded to the CFRP and wouldn't likely adhere to paint as strongly. Also, it was fine with me if the roof was painted only to the edges of the rubber side trim. I wanted the antenna and side trim masked and painted around. He told me that they wouldn't offer a warranty if all trim wasn't removed prior to painting. Jeez, these guys must not want the work, or maybe they want to create unnecessary work so that they can charge more.

I'm beginning to favor wrapping rather than painting. Unfortunately, the shop that did a great job wrapping the roof of our 2019 i3 has no more metallic silver vinyl in stock so would have to special order a roll. They charge $200 for a special order plus the installation cost, $650 total, which is pretty expensive for a roof wrap.

Do you know whether CFRP can be painted without damaging it?
oof. no way.
my roof delaminated in February. right-a-way i investigated and i found a good paint shop.
first attempt was to try and save the look of the roof by sanding then spraying several coats of clearcoat. the discoloration of the roof was too noticeable and we went with the back up plan. sand back down do the fiber and do two coats of gloss black to match the car and a coat of clear. this thing looked like glass it looked great. if you skip step one... going straight to sanding and painting it should be about $500 USD. and you should be good
i opted out for going back to that shop a couple of months later and getting the roof wrapped in a white carbon fiber 3M wrap. $450 since it was special order... could have been as cheap as $350 if i would have chosen an option in stock. my advise, dont try and safe the roof.

 
oof. no way.
my roof delaminated in February. right-a-way i investigated and i found a good paint shop.
first attempt was to try and save the look of the roof by sanding then spraying several coats of clearcoat. the discoloration of the roof was too noticeable and we went with the back up plan. sand back down do the fiber and do two coats of gloss black to match the car and a coat of clear. this thing looked like glass it looked great. if you skip step one... going straight to sanding and painting it should be about $500 USD. and you should be good
i opted out for going back to that shop a couple of months later and getting the roof wrapped in a white carbon fiber 3M wrap. $450 since it was special order... could have been as cheap as $350 if i would have chosen an option in stock. my advise, dont try and safe the roof.


I was under the impression, maybe falsely, that auto paints these days are water-based to eliminate the volatile petrochemical solvents in past paints. Anyone know for sure?

I could understand that petrochemical solvents might damage the CFRP clear coat, but that doesn't seem likely for a water-based paint on a roof that is designed to be fine when wet.
Hey Art -

Industrial and auto coatings are still mostly solvent-based. (Not directly relevant, but your average paint booth doesn't do anything to capture those emissions; it just filters incoming air for particulate, and blows the unfiltered solvent-laden exhaust out upward, to avoid being a direct nuisance to neighbors.) But back to the point, I've sprayed solvent-based coatings on FRP (not so much CFRP, but same-same) on many, many occasions over the years with no deleterious results. That'd be old-school polyester (surfboard) resin composite, as well as low-odor epoxy resin items. They're completely inert once cured, and ideal surfaces to spray because they're disinclined to contain any moisture and certainly not going to rust/corrode under a coating. You can't hurt them with any solvent you'd normally use in such an endeavor, so I don't know what that guy was talking about (I mean, were they going to slather methylene-chloride-based paint-remover on it to start with? Yeah, that might cause a problem...)

I've got nothing for facilities, or I'd be spraying my own (probably this weekend) - been kicking around the idea of using waterborne/based just to avoid the solvent mess/cleanup, but even that's not such a big deal. (Maybe at the new house, which has an actual garage...)

Since you're going with a solid color (metallic gold) the question will come up as to whether you'll want a two-stage (color followed by clear) which I think even after all these years can't be guaranteed to peel (clear flakes off in the UV) but you can get a really good gloss out of a single-stage, even if it doesn't have quite the depth of the two-stage.

I wish I could recommend a particular body shop, but I'm totally out of touch with them these days.

BTW have you come across details on how to remove the three adjacent panels (left/right/back of the roof?) I'm pretty sure that's in my near future - can't stand the idea of masking off rubber flaps and letting overspray drift into those channels if I can avoid it. If you find another shop you trust, they'd probably consider doing the same - if you can bring them up to speed.
 
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