# pressure treated



## rangie (Apr 21, 2007)

Newbie question: 
What's the deal with painting or staining pressure treated wood? I've heard so many different things, such as waiting 6+ weeks to let it dry out, never use latex, etc. 

Is there an agreed consensus with how/when to apply top coats? If I buy lumber tomorrow, when can I paint it?


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## MAK-Deco (Apr 17, 2007)

If you buy it tomorrow?? I would say no, prolly been sitting around getting wet somewhere. PT is usually pretty wet for a long time I have had oil and latex fail on it cause it was to wet.


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## slickshift (Apr 8, 2007)

No agreed consensus

The sales people of some kinds of PT will holler at you till their voice is gone that you can paint it right away

I can personally tell you that's a crock

The people in the field will tell you in reality it depends
It depends how wet it is as to how long it needs to dry
But you can NOT always paint it right away like the sales people say

Others and I can tell you, if you wait a month or three, you will NOT have a problem

If I do it in less than 3 weeks it's because the customer insisted and I void my warranty
Sometimes it's even held doing it that soon
Sometimes....


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## Wolverine (Apr 17, 2007)

I think that too many sales people these days make 'blanket' statements. I'm not going to answer this question... but... I'm going to discuss the technical aspects. So, what would cause a failure? Better yet, what causes GOOD adhesion?

It's good to think of wood as a sponge. If the sponge is dry, it can accept a coating and the coating can penetrate the surface of the sponge to a deep level. Once the coating gets hard inside the dry cavities of the sponge it's got good adhesion. 

Now, if the sponge is soaking wet, the coating can not penetrate and will have limited cavities to fill. So, when it gets hard it has only filled small pours on the very surface.

Next, is the question of the ability of the liquid to penetrate the substrate. In other words, if you pour water and molasses on concrete... the water is going to penetrate faster. So, you've got to have the coating penetrate the wood before it gets hard. So, bringing it back to this discussion is the question of water or oil? IN GENERAL, oil based coatings that contain solvent penetrate wood better than water based coatings. Again... IN GENERAL... However, waterbased coatings can be modified with various silicones and fluoropolymers to lower their surface tension to make them just as effective or even more effecting. So, the point of that was to say that you can't make a blanket statement in regards to water or oil!

So, why do people say not to use latex? Can anyone answer that based in this information?


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## DelW (Apr 18, 2007)

Great, you just gave me a headache.:w00t: 
Seriously though, that is a good way to explain it to the HO to get them to understand why you must wait until its dried out to an acceptable level.


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## Brushslingers (Apr 11, 2007)

Wolverine said:


> Oil based coatings that contain solvent penetrate wood better than water based coatings.
> 
> So, why do people say not to use latex?


You said it clear enough ole buddy ole pal... paintchemifromhell....


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## Rich (Apr 26, 2007)

rangie said:


> If I buy lumber tomorrow, when can I paint it?


when it's dry


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## slickshift (Apr 8, 2007)

Wolverine said:


> So, why do people say not to use latex? Can anyone answer that based in this information?


Latex primer on PT?
Because we have no idea if various silicones and fluoropolymers were added to the latex primer to lower their surface tension to make them just as effective or even more effecting.
Least that's my story anyway, and I'm sticking to it


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## Primer Guy (Apr 20, 2007)

Wolverine's got it right. Also, some of the new latex primers have extremely small particle sizes which help with the penetration. That being said there is more than one method of pressure treating wood. Painting any pressure treated wood where the treatment chemicals haven't leached out completely is "iffy" at best.


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## Workaholic (Apr 17, 2007)

MAK-Deco said:


> If you buy it tomorrow?? I would say no, prolly been sitting around getting wet somewhere. PT is usually pretty wet for a long time I have had oil and latex fail on it cause it was to wet.


I agree with this PT can stay wet awhile, 3 months or so after being put up.


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## Joewho (Apr 17, 2007)

Wolverine said:


> I think that too many sales people these days make 'blanket' statements. I'm not going to answer this question... but... I'm going to discuss the technical aspects. So, what would cause a failure? Better yet, what causes GOOD adhesion?
> 
> It's good to think of wood as a sponge. If the sponge is dry, it can accept a coating and the coating can penetrate the surface of the sponge to a deep level. Once the coating gets hard inside the dry cavities of the sponge it's got good adhesion.
> 
> ...


read:http://www.naturalhandyman.com/iip/infxtra/infpre.html


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## welovepainting (May 13, 2007)

We always use oil primers and latex topcoats on wood. Ive yet to find a latex primer to write home about. In my opinion oil primers penetrate, and stainblock better, if it's a really thick primer you want to thin it 15%-30% that way it soaks into the wood like a stain. Also I wouldn't paint PT wood I would stain it, that's my personal preference.


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## Joewho (Apr 17, 2007)

Wolverine said:


> So, why do people say not to use latex? Can anyone answer that based in this information?


I just now got the point. :blush: Like slick says, we don't know if silicates or fluorodaisies are in it. Reading an msds, we can look for the chemicals but still, knowing what to look for and how much is a mystery.

The link I posted doesn't answer your question, but it's the perspective I'm trying to point out.

This is great, I'm trying to keep up with your posts and lurn sumtin, but it is a whole perspective that has to be applied to practical applications. Takes time.
Thanks for your posts.


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