Just wondering, I had a new porch floor put on partially,with yellow pine, i think, the rest was fine, then I also had treated lumber used for railings and posts etc, but is it correct that the only paint I can use for the treated is stain/paint, but the paint I use for the yellow pine is porch/floor paint which cannot be used for treated? But can I use stain/paint for treated, for the yellow pine? Hope u understand that! I am just trying to save money. I already bought the paint for the yellow pine thinking I could use it on the treated also. Thanks!
Mona

You can use the same paint or stain for both. However, the big deal is how wet the pressure treated wood is. Some PT comes kiln dried and can be primed and painted (or stained) immediately. Non-dried PT, like what you find at most big box stores, will need to dry first. Dry time will vary depending on how wet the wood was to start with and how dry the wood remains once installed. If your porch gives decent protection so that your railings remain dry during rainstorms, then 2 to 3 month dry time is reasonable to paint or stain.

What you use does make a difference too, water based stains will adapt better to the slightly wet surface. If you paint, then use a primer designed for wetter surfaces - like Ben Moore Fresh Start.

Mona:

This is a long post because you need a harder paint on your floor than on your posts and railings.

Hang on to that paint, and you will be able to use it.

You see, the reason it's suggested that you don't paint pressure treated wood is because the pressure treatment involves forcing a water based chemical into the wood. Then, the chemical remains behind inside the wood and the water gradually evaporates from the wood. Any paint you put on that pressure treated wood while the water is still evaporating from it will peel off because of the evaporation of moisture from it.

Now, there doesn't seem to be any concensus of opinion on how long to allow pressure treated wood to dry before painting it. And, that's to be expected since weather conditions are so variable. Just to be on the safe side, I tell people not to paint their pressure treated wood for 2 years, but that's a conservative estimate that's likely to be on the very safe side. On the other hand, any paint you bought recently will easily keep for 2 years.

What you can do is buy a wood moisture meter and measure the moisture content of your pressure treated wood to determine when it gets down to 19 percent. 19 percent is what the moisture level of "kiln dried" construction grade lumber, so primer and paint should stick well at that moisture level and lower.

Now, for your yellow pine porch floor:

You should know that the reason certain woods are yellowish or reddish in colour (like Southern Yellow Pine, Redwood, Cedar, Red Oak, etc.) is because they have a lot of "tannins" in them. Tannins are chemicals produced by trees that were used in the leather tanning industry in the 1800's, from which they collectively got the name: "tannins".

Tannins are highly soluble in water, and so if you use a latex primer over that Yellow Pine, you're likely to see yellow or beige stains on the dried primer. To prevent that, it's generally recommended to paint over woods like this with an OIL BASED primer first, since tannins aren't soluble in the mineral spirits thinner of alkyd primers.

However, the fact that this is a porch floor means that to get good service from the paint, it has to dry to a HARD film. Otherwise, the dirt that accumulates on the paint will be embedded in the surface of the paint underfoot, and you'll soon start to see dirty "traffic lanes" on your porch.

This is the reason why every paint manufacturer will use the hardest drying alkyd or polyurethane paint they have as their "floor paint". I have tried using latex "Porch & Floor Enamel" in my laundry rooms, and they're a joke. They're simply not hard and durable enough to stand up well on a working surface like a floor.

Oil based paints are durable enough, even exterior alkyd paints are hard and strong enough to stand up well on a wooden floor. I don't know about the USA, but in Canada in just a few days time, effective September 1, 2012, most oil based paints will be taken off the market. The only oil based paints that will continue to be available to the public are high gloss alkyd paints intended for painting metals. Oil based PRIMERS will still be available, however, and I can't explain why primers are environmentally acceptable but paints aren't.

So, if I were you, I would go to this web page:

http://www.thecomexgroup.com/

and see if you recognize any paint company names at the bottom of that page listed under "Our Companies" as operating in your city.

Comex is a Paint manufacturing company headquartered in Mexico that sells it's paints in the USA and Canada through the paint store chains you see listed under Canada and USA, and Comex is making some pretty remarkable paints these days.

Since I expect the USA will follow Canada and take oil based paints off the market, you need to find an environmentally friendly paint that dries as hard as an oil based paint to stand up well on your porch, and I'd recommend you go to any of the paint store chains Comex operates in your area and consider either:

1. ENVIROGARD - This is a latex paint, but the acrylic resins it uses crosslink very densely, making for a much harder and durable paint than a normal latex paint. So, you put it on just like a normal latex paint, and then once the paint is dry to the touch it starts "curing" as crosslinks form within and between the acrylic resins. Over the course of a month or so, the paint will become very hard and durable. Some people call Envirogard a "one component epoxy", but it's MSDS sheet says that it contains acrylic resins, thereby making it a "latex" paint. My personal experience with Envirogard is that it cures to a harder and stronger film than any other "latex" paint I've ever used.

2. MONAMEL - I just used Monamel for the first time last week on some kitchen cupboards, but I tested it before purchasing it and using it on my cabinet shelves.

Monamel needs some explanation. It's an oil based paint, but the alkyd resins are suspended in water. So, what evaporates from the paint is water, but what remains behind on the painted surface are alkyd resins that cure by reacting with the oxygen in the air just like a normal oil based paint.

I haven't tested Monamel long enough to see if it yellows under dim lighting like conventional alkyds and oil based polyurethane paints do, but that wouldn't affect you because no oil based paint that's exposed to direct or indirect sunlight will yellow with age.

The only thing I don't like about it is that it takes a good two weeks to harden up to the hardness of a fully dry alkyd paint.

Also, wood swells and shrinks with changes in it's moisture content caused by seasonal changes in humidity. Since using Monamel results in an alkyd film, it would stand to reason that Comex would make both an INTERIOR Monamel and an EXTERIOR Monamel for use on wood outdoors. The exterior version wouldn't dry to as hard a film so that it would retain sufficient elasticity to stretch and shrink with wood outdoors. But, I don't know that an exterior version of Monamel is available as that's a question I never asked.

If it wuz my yellow pine porch, and I knew that oil based paints were going the way of the dinosaur, I'd prime with an exterior oil based primer first, and then top coat with either Envirogard or an exterior Monamel, if an exterior Monamel is available.

This message has been edited. Last edited by: Nestor,

thanks guys, I do plan on letting the pt dry for a few months, since it was just put on..what I got was Valspar, latex satin porch and floor paint. I am thinking of just taking that back if I cannot use it for the pt and just getting the stain and use that on everything, do u agree with this option? thank you so much the explanation on everything Nestor, big help!

A major downside that you will face if using the same paint will be that the paints are designed for different surfaces and to withstand different weather conditions on that specific surface. There are plenty of deck finishes that would work well for your situation that are generally inexpensive. Chances are you would use the paint you already have in the future anyway for something else or for touch-ups.

once you paint, you can't go back to stain. I'm an old crank in some respects, and I strongly prefer a penetrating oil stain. it protects, you can reapply as needed every 2-5 years, and there is no peeling, blistering, or brush marks.