I am using pressure treated 2x stock to make a platform for an AC compressor (code here in SW Florida) since the old one rotted after 15 years. I am wondering what anyone knows about painting it as my only experience is with stain.
I assume it needs to dry out for a good while but how about a primer? Please let me know your suggestions as the plain wood is just plain ugly and it needs to be white when it is all done.
Rich
Replies
There's a thread about painting PT Lattice that I started a while ago (2 months) ... I'm still in the middle of the project and will provide a complete report at some point, but the most consistent advice I got was a)make sure it's dry (I parked mine in the dining room for 2 dry winter months), and b)use a good primer - I used California Troubleshooter fast drying linseed oil-alkyd after hearing it from several experts I trust. I just finished putting it on and it seems fine (but ask me again in 20 years). I plan to top coat with a California exterior latex.
oh, and don't even ask how much my wife enjoyed having 5 4x8 sheets of lattice drying in the dining room!
Good luck ... Bill.
I laughed at that one, I had pine flooring stickered to climatize in the main hallway for what was suppose to be a month but turned into 8months. Wife was real impressed!!
Rob
I was advised by a paint rep and have had good luck using acrylic primer and finish coat. The pressure treatment is waterborne so oil base paint won't adhere well until it is dried out.
Thanks for the advice. My wife would not want a miniature pile of deck building materials in the house for a minute. Interesting that oil base won't adhere, I would have thought otherwise not knowing the make up of the treatment products.
I don't have the luxury of drying time before I build so I have to hope the moisture drops naturally in the near future. I'll look further into the products mentioned to make an educated decision but will keep checking this thread for words from the wise.
Rich
Speed,
I think I would call the wood treater that produced the material. Ask them what coatings will work. The stuff I get here has an 800 number on the stapled-on tag that's on each piece. Those guys are supposed to know all about the chemistry.
The US Forest Product Labratory say that you can paint it as soon as it is dry to the touch, usually a week or two.
The lumber is KD before treatment and that the excess moisture is just surface mositure from the treatment.
just surface mositure?????????????????????????????
I gotta call the hand on this one. First time I've ever disagreed with you Bill, I think. Maybe you are on the W?est coast where it is incised fir?
i have taken a bath.showeer in that "surface moisture" when ripping the SYP PT lumber. We call it "pond dried" because it is so heavy with fluid. 2x10s soaked thru and thru!
I have milled a mile of railings out of PT and had it painted. It is all holding great, but we always let it season for a season before painting. We use oil.
The reason oil based does not want to adhere on a long term basis is that it builds a watetight film so the moisture is trapped inside the wood. It will find a way to get out, by blistering the paint off. Latex will breathe a bit though so the moisture can dissapate through the paint. Another reason the oil base resists a good bond when wood is wet, is that the oil penetrates the wood a bit as it cures and finds tooth in the wood. When there is already a lot of water in those spaces the oil is seeking, it cannot find that mechanical grip it is looking for.
Oil and water just don't mix. So if you are painting before the PT dries pretty well, use a latex. If you can let it dry first, use oil.
That ought to be worth a few weekends fishing while you wait for just the right time to finish the project.
;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Surface water was a very poor choice of words.
I will have to go back to Hotley and re-read the definitions of free water and bound water to use the correct term.
Yes, some PT lumber is very wet. I have seen some that sprays more water when cut than my shower head.
But the water is not the same as in green lumber.
Here is what "Finishes for Exterior Wood" says. It is published by Forest Product Society based on the work of the US Forest Products Labs.
"The main consideration in finsihing pressure-treaded lumber is the mositure content of the wood. In some cases, the lumber may still be wet from the pressure treatment when it is delivered to the job site .... If the wood si still wet, it much be allowed to dry before finishing so that the moisutre content is less than 20 percent. The rate wood dries once in place in a complelted structure depends on weather conditions; UNDER WARM SUMMER CONDITIONS, ABOUT 2 TO 3 WEEKS SHOULD BE SUFFICIENT FOR DRYING (emphasis added)....."
In another section on penetrating deck finishes it has;
"If the decking amterial was given a factory applied water repellent (such as Wolman Extra) or if it was recently finished with a water-repellent preservative a semitransparent stain may not absorb propertly. In those sistuations, the wood should be allowed to weather for 2 to 3 months before finishings. This is the ONLY situation where it is beneficial to wait this long before finishing wood with a penetrating stain. LUMBER SHOULD NOT BE LEFT UNFINISHED FOR 6 MONTHS TO A YEAR AS INDICATED BY SOME PRODUCT LITERATURE OR AS RECOMMENED BY SOME PAINT AND LUMBER SUPPLIERS. (EMPHASIS IN ORGINAL TEXT.) A shor drying period sometimes be necessary (see subsection on Moisture Content in Chapter 6{which is what I copied above})."
Similar wording can be found in http://www.fpl.fs.fed.us/documnts/finlines/willi95a.pdf "Finishes for Wood Decks".
Thanks to all so far who have contributed to a more interesting discussion than I anticipated!
We're on the Gulf Coast in southwest Florida so we do have a nice breeze all the time to aid the drying of this lumber. Unfortunately our tropical rainy season seems to have started very early this year. One reason I considered paint is as a protectant which, after all, is the reason we really paint things in the first place. The fact that we have a choice of colors makes the aesthetic bonus one that is often taken for granted. In this case I realize it cannot always be assumed!
I just pulled labels off the butts of the lumber and lo and behold I found manufacturer information. Who'd a thunk it?
The 2x2's are from Universal Forest Products Inc. http://www.ufpi.com and their website does not directly address painting but I did find a link to staining that basically instructs against painting. See it at http://www.ufpi.com/literature/ptaddingcolor-197.pdf. This leads me to select a solid pigment stain since it will not be used for foot traffic. Now hopefully I can find one in white!
The balance of 4x4, 2x4 and 2x6 are from Robbins Mfg. Co. I found their website on Google (where else?!?!?) and it is at http://www.robbinslumber.com/lumber.html. They have a toll free number so I will call when they open later this morning. If they say otherwise, I will post more information.
As one person asked, indeed I could use masonry down here but it would cost much more, I hate to unnecessarily mix mortar, it is too difficult to achieve any level of decent architectural detail and I wouldn't be able to use my new framing nailer!
Beep beep!
Speedster
But it would give you an excuse to buy a new cement mixer.
And some trowels.
And an edger.
And some...............
Well Robbins said different. They believe that PT can be equally stained or painted. The recommendation is allowing 6 to 8 weeks after it is used to dry down but they expect in FLA it is much less time due to sun and breeze. They say water or oil can be used but their treatment is a water-based chemical process. Sounds so healthy!
On that note, I just might risk it since I like the look of a clean paint job.
Beep beep.
bought a Behr white stain at home despot. Not bad, but on the PT lumber I stained (2 coats) it now looks a little greenish after a year. Probably ok for a platform where looks are not paramount. I would go w/ a concrete pad, though, it possible
I can pretty well go along with that. I think the local climate will determine how long it needs to season. I usuallu build these in the fall or winter so by the time it is warm enough to paint, things have seasoned out. But if it does go a full year, the painter simply needs to sand a bit more before slapping the brush to it.
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You may want to consider a solid color stain instead of paint. No primer needed, and is less likely to peel.
I was browsing the Forest Products Lab website, and they claim that only a few (1-3) sunny or windy days are needed to dry out lumber before painting. I was somewhat suprised, but hey, they are susposed to be the experts.
They also had some interesting info about backpriming and mill glaze. Worth a look.
http://www.fpl.fs.fed.us/
Eric
Is concrete forbidden by code? It seems that would be a much more permanent solution. Pressure treated wood resists rot and insects, but weathering still destroys it.
speedster, Check with your HVAC supply co. You should be able to find a molded plastid or fiberglass platform cheap, and no maintineance.
I have a method that works for me although I've never seen anyone else use it. I apply orange shellac to PT lumber after it dries some. Usually 4 or 5 days of clear weather is long enough. I skip the primer, the shellac acts as a primer and paint with acrylic paint, usually two coats.
mike