Message Thread:
Problem with paint on sapele
10/20/16
Website: http://trimitsiswoodworking.com
For several years, we have been using sapele for our paint-grade exterior woodwork. For us, sapele has the right combination of rot-resistance, dimensional stability, machinability, availability, and relative affordability. We had previously been using South American mahogany, and then Spanish cedar, changing species as availability and cost forced us to do so.
While our experience with sapele has been largely positive, we’ve recently had some difficulties that may be attributable to our use of this species. About 18 months ago, we fabricated a set of 6 very large carriage house doors (plank on frame construction) for a historic carriage house in the Boston area. We used quartersawn kiln-dried sapele (moisture content approximately 9%), primed it with a high-quality latex primer (Benjamin Moore Fresh Start) and delivered the doors to the project’s general contractor for installation and finish painting.
Almost immediately after installation, the finish paint began to blister, in such a way that the primer remained well-adhered to the underlying wood. The finish paint was a Benjamin Moore exterior-grade acrylic paint. I initially attributed the finish paint failure to sloppy painting technique, or contamination of the primed surface during installation of the doors. However, the paint failure is continuing (new blisters forming) to this date, 18 months after installation. The painter has sanded off the finish paint in some sections and repainted, with the same sort of blistering reoccurring. Furthermore, some of the doors exhibit severe blistering on one plank, while a neighboring plank is free of paint failure. The doors are exposed to direct sun for several hours each day and become quite hot (sapele seems to have a high thermal mass). There is no concern that the doors are getting wet.
I am reluctantly starting to consider that the sapele may be at fault for the paint failure. I am trying to understand if there may be some volatile compound(s) in the kiln-dried wood that can migrate through the primer coat and cause the finish coat of paint to lift. I have had numerous conversations with technical representatives of the paint manufacturer, but they haven’t been able to offer an explanation outside of contamination of the primer. If anyone has any relevant experience or thoughts about what might be going on, I'd be very grateful to hear them.
Many thanks!
Milton Trimitsis
10/21/16 #2: Problem with paint on sapele ...
Why not try some other brands of paint on some samples boards? Did you check the moisture content of the wood?
10/22/16 #3: Problem with paint on sapele ...
If your prime coat is remaining intact, it is unlikely that it is wood or primer related. The fact that the topcoat refuses to stay boned to the prime coat suggests some sort of contamination of the surface of the primer while onsite, or incompatibility between primer and topcoat.
I would look harder at the onsite situation, and the topcoat as the source.
Direct sun and dark colors can present some bonding issues, occasionally.
10/22/16 #4: Problem with paint on sapele ...
We do the same as you and never had a problem, and my painter only uses that primer on my exterior millwork .
Though my hardwood salesman started pushing Lyptus on us instead of Spanish cedar or African mahoganies . I will ask my painter on Monday but I would be pretty certain that it's nothing you did or used
10/22/16 #5: Problem with paint on sapele ...
I finally reached someone at Benjamin Moore's tech help line who was familiar with the issue I'm facing. He said that both SA mahogany and sapele were known for resin vapors escaping from the wood when it's exposed to lots of direct sun. He said that these vapors are transparent to latex primer but are trapped by glossy acrylic finish coats like the MoorGlo that was used in this project. He reported that using 2 coats of Ben Moore's 094 primer (fast-drying oil) improves the issue but does not solve it entirely. He also said that using a flat-sheen finish paint helps a great deal, as the flat finishes are more porous than the glossy ones. It looks like we may own this problem after all. The doors will need to be stripped. and I'm tempted to coat them with an epoxy consolidant like Smith's CPES prior to priming to ensure that we have no further problems. We'll do some tests first, but I'm nervous just going with oil primer. Bummer!
We've never had a problem with exterior standing trim we fabricate from sapele, but I think that's because the building acts as a heat sink, preventing the wood from getting hot enough to drive out the resin vapors. We've seen this kind of blistering on some sapele storm doors we've made, but I blamed it on the dark green paint that never seems to cure hard. That may be a contributor, but it looks like the wood species is not doing us any favors either.
I'm a bit at a loss about what species of wood to use for future door projects. Spanish cedar is too soft for entry doors, as is western red cedar. Any ideas? In the meantime, I think we'll use epoxy under the primer as our default treatment.
Thanks for the responses so far!
Milton
10/23/16 #6: Problem with paint on sapele ...
Milton,
That is good information you pulled from the Benjamin Moore rep. While this is a bad situation you were fortunate to find someone with knowledge of the problem.
I'm curious as to the topcoat color. Was it dark so as to induce an even hotter surface?
As to an alternate wood species I'd suggest looking into Utile. We've done a few projects with it and found it a good alternative to African Mahogany and Sapele. Between color, grain pattern and work-ability it may actually be the best SA Mahogany substitute.
I'm surprised you find Spanish Cedar too soft. We use it when we have to but try and stay away mainly due to the nastiness of the dust. We find it most unpleasant to work around but have never gotten a sense of softness from it like WR Cedar. I think it may be falling out of favor though as we are getting fewer requests for it's use.
Good luck in a tough situation.
BH Davis
10/23/16 #7: Problem with paint on sapele ...
Do not waste your time with Smith's epoxy then primer. Get some real epoxy primer. Interlux makes one. Marine shops always have it for finishing fiberglass and wood.
Awlgrip 545 is the boat industry standard for epoxy primers. But its expensive and better than what you need.
The
Epoxy Primer
10/24/16 #8: Problem with paint on sapele ...
Milton, Ive seen this problem also with a Sherwin Williams product. I didn't make the back door on one of my whole house cabinet jobs, but the back door blistered silver dollar size blisters all over. I think the wood may have been Spanish Cedar, but the front doors were W Oak and had the same problem.
KD should have less volatile outgassing than AD wood, in that higher heat drives them off in the kiln. I think it is just expansion of the air within the wood seeping out in places faster than these new finishes on top can let through, and the adhesion to the primer is the weakest point, so it just blows a bubble.
Adam, FYI, about 3 years ago I made a half round top pair of garden gates, which called for this same paint. I used Smiths CPES on them, and told the client on the front end that if my efforts failed and it blistered, that he needed to take it up with the paint store, but I didn't want to have to stand behind it. It was very dark green, and had a SW exposure, but didn't blister, so I think the CPES may have done the trick.
That is my two cents.
10/25/16 #9: Problem with paint on sapele ...
Keith,
I have no doubt that CEPS may have prevented blistering issues. We have done the same many times over the years with West System and MAS epoxies.
My point with using the Interlux products. Is simply that it is a waste of time to coat something with epoxy then prime it versus simply using an epoxy primer. Half the labor if it was all paint, but most of us would do more a better prep job between the CEPS and a primer. So using an epoxy primer saves half the normal application time plus some extra prep time.
12/5/17 #11: Problem with paint on sapele ...
Could you use a shellac based primer like B-I-N Shellac-Based White Interior/Spot Exterior Primer and Sealer? I have a similar question where I need to refinish an old mahogany door and replace panels with new sapele and then finish with a high gloss paint, I know blasphemy, but its not my decision. Whats the best primer to use?
12/5/17 #12: Problem with paint on sapele ...
Doug, is your application for interior or exterior use? If exterior, I'd be worried that a shellac-based primer would not have enough flexibility to accommodate movement in the wood. If interior, it might work, but I have not tested it. The only primers that I'm confident about are a double coat of Benjamin Moore 094, their fast-drying oil primer, and Smith's CPES, a low-viscosity epoxy.
2/13/18 #14: Problem with paint on sapele ...
Milton,
Thanks for the response. It's an exterior door, and we ended up making a completely new door with Sapele. My local Been Moore recommend the BIN shellac primer but would I be better with the Been Moore primer,and 1or2 coats?
2/13/18 #15: Problem with paint on sapele ...
Website: http://www.trimitsiswoodworking.com
Doug,
If you don't want to go down the CPES rabbit hole, I would use 2 coats of Benjamin Moore 094 primer, their fast-drying oil. For reasons that I don't completely understand, it seems to work better than their penetrating oil primer in this application.
Good luck!
Milton
ps - I'd love to see photos of the door.
5/4/22 #17: Problem with paint on sapele ...
I'm facing the same problem. When I painted in California, we used redwood for the exterior brick mold. The ONLY thing that wood stop from the oils bleeding back through was an alcohol base primer, then Sinclair paint. The shutters I'm painting some are 8' tall, and cost $1700 e.a. to make, it's a real disappointment ment. Some of the Olds on the 90 yr old house were blistering BADLY and the paint was gooie or soft. I know now I should have researched the wood before priming and painting the new ones. I'm gna look for some alcohol base primer and try it maybe. Thanks for your alls posts!
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