Message Thread:
Wood species for black ext painted finish
11/12/18
What would be the best decay resistant wood species for charcoal/black painted exterior t&g vertical siding?
My concern is the volatilization of any natural pitch, resins, sap, or oils within the wood due to heat when in direct sunlight which might result in blistering. The house, which is only 4 years old, currently has Western Red Cedar siding, and the WRC just isn’t tolerant to the high temps due to the dark color, and needs to be changed out.
Genuine mahogany was a consideration.
Any suggestions would be greatly appreciated.
11/12/18 #2: Wood species for black ext painted ...
My guess is it has more to do with the installation (nailing) method and the lack of finishing all the way around the cedar (backs, edges, etc) that is the problem vs. the specie.
11/13/18 #3: Wood species for black ext painted ...
Family Man,
I didn’t do the installation or the initial painting. Everything was however back and edge primed, and installed over a vapor barrier with a breather apparatus. Moisture content readings are negligible throughout. Finish failure is board specific after 3 x strip/refinishes, removal being performed non-chemically. There’s evidence of bacterial wetwood, the cedar exuding a sticky substance, not tannins. Some boards when re-primed develop micro-bubbles, having the appearance of solvent pop, yet with a sticky/shiny, yet small amount of what looks like sap at the eruption sites. Blisters occur within days after finishing. Failure is heat activated, only in direct sunlight. There’s no evidence of trapped solvent or moisture in blisters. Beneath blisters is a sticky exudate on board face which is breaking down the prime coat. Nothing’s face nailed except the first and last couple of boards in a run. Toe fastener holes at the tongue edges were not primed during installation. I would have suggested loading them with primer though. Being that the failure is board specific after 3 attempts to remedy, I’d be reluctant to try cedar again. Architect suggested switching out to cypress or AYC. I’m not certain that cypressene oils would pose a problem with a dark color on cypress, and have only finished Alaskan Yellow Cedar once in an exterior application, and not with a dark color. I’m not familiar with AYC chemistry and don’t know how it would behave when painted a dark color. I need to be super cautious with recommending a species, because any potential failure would be on me. I’m just the finisher, not a finish carpenter by trade.
John
11/13/18 #4: Wood species for black ext painted ...
Sounds like you did a good and thorough investigation. Living right next to the source of the finest cedar in the world and not having worked with it for two decades, in which I am sure the quality has declined, are tainting my first reply.
I don't have an experience with the cypress or much with the AYC. If it was my butt on the line and money was no object I'd probably use white oak but secondly I'd keep my film to an absolute minimum. If paint was required I'd first stain the wood behind the paint, a pre primer if you will- allowing more than enough time for it to dry and then doubling the amount I just gave it to be sure- and then keep my paint coats thin. If I could I would attempt staining multiple applications to see if an opaque stain would meet their needs.
Regardless, the homeowner should be aware that in a warm climate, black paint on real wood siding- they are asking for the very top end of of the scale in regards to upkeep and maintenance. It will be a constant money pit. You will be back early and often I would bet.
But I'll admit upfront I'm not expert in this particular scenario, just shooting from the hip knowing wood and finishes extensively but not in the particular situation. I hope someone who has tackled this with success can chime in. Good luck.
11/13/18 #5: Wood species for black ext painted ...
Website: decorapainting.biz
You might be dealing with an issue called Slime Flux. Here is a quote from a member at another forum that you might find useful.
“The problem turned out to be a condition called “slime flux” aka bacterial wetwood. Slime flux is a rancid fatty acid, which is produced through fermentation in Clostridium bacterium infested trees. The slime flux won’t dry down/fully crystallize during the kiln drying process and exudes from the wood after being reactivated by heat and solvents in oil primer. That would account for the blistering and goop. The bacteria produces an enzyme resulting in shake, separation of growth rings which is sometimes mistaken for checks. It also produces dark streaks running parallel to growth rings. I’ve been seeing a lot of this lately on white oak, the first time ever on cedar though. Not too common. Had a guy with a PhD in forestry identify the problem. No permanent fix aside from a tear off/ reinstall. Apparently the stuff will bleed completely through overlaid PVC trim. No way to hold it back.”
Here is a link to the thread I’m quoting because it contains some additional info you may find useful.
https://www.painttalk.com/f2/western-red-cedar-solvent-soluble-extractives-92073/
11/13/18 #6: Wood species for black ext painted ...
Thanks Jamie,
That post @ Paint Talk was mine.
I put it out there with a couple of forestry professionals/PhD’s and all pretty much agreed, including this site’s moderator.
Got the okay for the tear-off/replacement yesterday, just need to come up with a species of wood that will not be problematic.
It’s been an ongoing issue, now under the intense scrutiny of homeowner, the homeowners being absolutely wonderful in seeking a lasting remedy.
J
11/13/18 #7: Wood species for black ext painted ...
In depth info for sure and not to play devil's advocate but how about Hardie Board planking. I worked for a guy that built coastal homes and that was the long term remedy.
11/13/18 #8: Wood species for black ext painted ...
Thanks for the suggestion Tiptop.
I “think” the finishing spec for Hardie Board calls for the paint color to have a light reflectance value no lower than 40, although I’m not certain. The specified color LRV is 12.8. I was looking into non-wood options. LRV seems to be an issue, dark colors getting too hot.
The material needs to be center-matched w/3” finished face and a serviceable reveal of a specified width and depth, allowing for clean lines between boards so that they won’t get clogged up with paint.
J
11/13/18 #9: Wood species for black ext painted ...
Correction on the Hardie, no LRV restrictions with dark colors....
11/14/18 #10: Wood species for black ext painted ...
Website: decorapainting.biz
Have you looked into Boral siding? If not, it might be a good fit for your project.
http://www.boralamerica.com/Media/Default/Resources/Trim/Trim-Installa tion%20Guidelines_0416-FINAL.pdf
Boral
11/14/18 #11: Wood species for black ext painted ...
Thanks Jaime,
I just looked at the Boral Nickel Gap T&G.
The dimensions are absolutely “spot on” to what I’m looking for...exact! Looks like it’s 40% cheaper from install to completion vs WRC, and a heck of a lot cheaper than mahogany.
Seems like they launched the product line in 2016. My only concern is long term performance.
I’m definitely going to pass this along as an option.
Thanks Again!
11/14/18 #12: Wood species for black ext painted ...
If I were only the painter there is no way I'd end up on the hook for the siding recommendation. That's the architect's, siding guy's, and/or homeowner's call.
John
11/14/18 #13: Wood species for black ext painted ...
Take a look at torrefied poplar or ash.
11/15/18 #14: Wood species for black ext painted ...
You know, there are designs that are just fraught with long life failure. Painting wood black is one. Just because they can mix the paint does not make it a good idea to use it on natural wood. I'd suspect black on any material could limit the life. Even steel painted black will absorb more ultraviolet and may cause color shift or paint failure from expansion and contraction on the south side. I'd consider your roll to be fraught with danger as well. The owners can't be saying good things about the original installer after being forced to change out the siding after 4 years. Good luck.
11/19/18 #15: Wood species for black ext painted ...
You don't say how much siding there is to paint. This is a product we use on boats that we work on. It has solved many issues in places where we normally have peeling and flaking from sun exposure. We've never painted any black, but have done striping with a dark blue with no failures. We've used it on wood with high moisture content on tabletops sprayed with clearcoats without failure. As far as using cypress, it moves a lot. Also if it is new growth cypress, you don't have to worry much about the cypressene oils as it doesn't start building up until the trees are 100 years old or so.
I also agree with Rich and John. Dark colors with a southern exposure is asking for problems down the road.
Good Luck
MultiWoodPrime
11/19/18 #16: Wood species for black ext painted ...
Thanks for the responses. It has been decided to produce mock-ups and put them to the test. Being a mixed species exterior, the siding only accounting for 1,000 sq ft +/-, with the painted mahogany on the windows and doors experiencing no issues, the client opted for mahogany as a first choice. In response to Scott’s reply, torrified wood looks beautiful yet would fight the design, although I’d be very interested in trying it somewhere. In response to Rich’s reply, the decision is frought with concern and/or scrutiny, and changing the color of the house was discussed, yet the color being an important design element, changing it would compromise the visual aesthetics. Maintenance will be ongoing. In response to the Cajun Craftsman’s reply, I’ve had issues “once” with some new growth cypress I left in my black truck on a hot summer’s day exuding only what was a “small” amount of resin. My concerns with new growth would be decay resistance and dimensional stability. On the other hand, I worked with sinker cypress this past year for an interior project and the stacked boards were practically welded together from the resins, having to use a rubber mallet to separate them. I don’t know how Frank Lloyd Wright’s painters faired when painting old growth cypress his dark signature Cherokee red color?? The product for boats mentioned by Cajun Craftsman, I’m “guessing”, is an impregnating epoxy clear primer of sorts? If so, I would attest to the technology having used it on a difficult substrate where vapor pressure/moisture and adhesion issues were concerns, having worked beautifully without failure on what seemed to be an absolutely impossible surface which was prone to failure.
In response to Family Man’s reply, decades ago a dark color was trending in my location with WRC being the species of choice. Having finished WRC with dark colors, it was never an issue with -zero- failure. I’m guessing that forestry quality standards and/or coating technology might be slipping. White oak is commonly an overlooked species for exterior applications, the closed pore structure combined with high tannic acid levels make it a bullet proof choice. I’ve only seen it used for door sills and entry doors in my location. I’m guessing that the pronounced texture would requiring excessive amounts of labor to fill pores if the texture was deemed undesirable.
One other observation with wetwood, affected boards appear to have much higher absorption rates, absorbing solvents from paints, and out gassing after the coatings have formed a skin. I made note earlier that the blistering wasn’t due to trapped solvents. It appears that trapped solvents in affected boards are possibly a contributing factor. Thinking maybe this has something to do with the degradation of the cell wall structure, making it more absorbent?? The degradation isn’t visible to the unaided eye, yet ring shake is a symptom, wetwood being the cause for ring separation in many instances. Also, what I’ve learned from what appears to be mineral staining on problematic boards, the staining from what I gather is due to disruption of the water transport system, water carrying mineral solutes, with minerals being deposited at sites of infection. There’s very little written info on this, requiring a bit of detective work, so my conclusions may have some inaccuracies. I guess the bottom line is 5 failures by 3 different vendors/contractors in 4 years utilizing 5 different methods likely indicates that it is a wood issue or that the species just isn’t conducive to being painted a dark color. From what I’ve gathered, bacterial wetwood is apparently not all that uncommon in old or 2nd growth WRC heartwood. With 99% of WRC being utilized for unfinished applications or finished with breathable stains and/or water repellents, aside from wetwood exhibiting visual defects, it’s not of any concern. When finished with lighter colors, it doesn’t seem to be much of a concern except when water is trapped in pockets or isolated regions. Having painted a house white 3 years ago with 72,000 linear feet of WRC t&g siding, the only failure was on a bundle of material where the builder jumped the gun installing it before being back primed. I have experienced problems only once with a light color where the affected boards had what appeared to be water logged isolated pockets within the wood. The boards were noticeably “heavier” than the unaffected boards. I’m guessing that may have been due to wetwood.
Thanks again for the responses,
J
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