aggressively thinning latex paint?

Perhaps, but the application and prep were meticulous. All treads and risers were removed and thoroughly scraped, wire-brushed, sanded, and brushed. Primed with oil primer all six sides. Top-coated with 2 coats of porch and floor latex all six sides.

So the other possibility is perhaps the conventional wisdom of latex topcoat over oil primer is not universally correct for all applications. FWIW, I spent 30 minutes in a paint store this afternoon reading the label of each and every different exterior primer, both oil and latex (8 or so different cans). Not a single one of them listed exterior wood floors or steps as an acceptable application. Some of the highly-touted brands such as Zinser 123 and Kilz explicitly excluded exterior wood floors and steps.

It will take a couple of years, but my experiment with the backyard porch steps should be most interesting:

On 23 Aug 2006 17:04:16 -0700, with neither quill nor qualm, "Ether Jones" quickly quoth:

By overthinning the latex paint, you break down the chemical bonding of the "glue" base which holds it together. Any paint over the top would be more easily removed.

Jus' cuz.

Blistering and peeling are indicators of moisture damage. Since the primer came up, too, I'd wager that it was the wood which was still wet.

Make POSITIVE SURE that the wood is dry, the primer is dry [I'd use all oil-based if it was available, all latex (including primer) if not.] As you have seen, 2 days at 85F wasn't enough to dry the wood after washing. Also, make sure it's properly rinsed. Soap films can be really tenacious. Give it a week to dry AND protect it from dew.

Another possibility arises when you paint things out in the sun. It's best to paint while it's warm and dry, but not in the direct sunlight if at all possible. That, too, can cause blistering as the outside layer of paint dries more quickly than the inside, sealing in more moisture than it normally would. (I've only read about this part, not experienced it firsthand.)

Also avoid cheap paints. Good, durable, long-lived paint ain't cheap.

G'luck!

On 24 Aug 2006 14:04:23 -0700, with neither quill nor qualm, "Ether Jones" quickly quoth:

Floetrol is a latex medium with additional binders which are not in water. It's good stuff. (I have a quart of it on my kitchen floor waiting to be used with the latex enamel I'll use to repaint all the interior house trim this month.)

polymers and surfactants to help the paint flow and "skin" properly.

Perhaps here:

Yes. Take an ounce of Elmer's glue. Thin it with water. Does it still work as well? You've thinned out the chemical bonding. Ditto your thinned paint. Most manufacturers ask you not to thin more than 10% because it messes with the durability of their paint formula. You're thinning 25-50% and it'll come back to bite you, ah gare-on-tee.

If you're low on engine oil in your car, it is recommended that you don't add water to that, either. ;)

This just in: Everything We (You) Know Is Wrong. The sun isn't going down, the horizon is moving UP!

You wont know with your experiment till it fails, what if it peals in sheets in 4 years, well it could. Quit experimenting and follow directions. Primer for decks is often paint thinned properly, properly is the key.

That was the whole point of the message to which you were responding: WHAT directions?

Can you recommend (by brand name and model number) even ONE primer whose labelling explicitly allows usage on horizontal wood surfaces exposed to weather and foot traffic?

polymers and surfactants to help the paint flow and "skin" properly.

Or not. I've read that link. There is no mention at all of polymers or surfactants. All its says is that Floetrol contains "conditioners". My shampoo contains "conditioners" too... maybe I could use that? It's cheaper... :-)

It's also recommended in my car owner's manual that I do NOT add third-party additives to my oil, either. Just like the label on my latex which says "Do not thin"... not "Do not thin, except with Floetrol, which, although made by our competitor, contains the exact same chemistry as our proprietary acrylic binding system".

I'll probably pick up a gallon of Floetrol today and give it a try on some of the boards I am refinishing and give it a fair try. It would be nice to have more information about it though. Like what's in it.

Just paint the f****ng boards and shut up, already!

Sheesh!

Steve

The sarcasm is misplaced.

If you don't know what's in the product, don't be telling people you do.

By the way, patents are not "private". If it was patented (which it is not), that information would be publicly available.

Good God, Man. Do you beat dead horses for a living, or just for fun?

Steve

Do what the deck paint label says, or call the manufacturer. For oil deck paint the usual recomended way by manufacturers that is printed on labels is thin the oil paint with thinner. Ive only thinned latex to make it original in thickness after it has thickened by air, Ive never thinned to spray. The usual max recomended thinning of latex is 10% for spraying. Each product is different, follow its instructions. Your previous failures may be to damp a wood [ use a moisture meter ] I do. Or to hot in sun, to humid, to cold etc etc. Or even crappy paint.

Just got off the phone with the tech support person for the latex I am using this year. What she said surprised me but also fit the facts of my personal experience. She said DON'T USE PRIMER. When I asked why, she said there ARE NO PRIMERS that hold up well to foot traffic. Well, that certainly is in agreement with my previous experience, and would explain why the paint on my porch steps failed so quickly.

Two years ago I oil-primed and latex-topcoated the porch steps, and the system failed after one year. The paint was adhering to the primer, but the primer was peeling from the wood. The latex I used back then was Dutch Boy Porch and Floor, and the label directions said to use an oil primer, so I did. In an earlier post, I speculated that the reason for the failure might be that the "conventional wisdom" (latex topcoat over oil primer) did not apply to what I was trying to do (horizontal wood exposed to weather and foot traffic). Looks like that might be correct.

The porch and floor latex I am using this year (made by Sherwin Williams) does NOT say to use an oil primer, or any primer for that matter.

The tech rep also said that even though the label says "do not thin", it is OK to thin with water up to 12% FOR THE FIRST COAT ONLY to improve penetration into hard-to-reach places as long as there is a second, unthinned coat applied.

At any rate, the next couple of years should be interesting to see what happens. One set of steps I power-washed, let dry, and painted with no primer, just like the label said. On a few of the steps I thinned with water for the first coat. The other set of steps I disassembled, planed, power-sanded, and applied paint/primer/stain/sealer in many different combinations to see which would hold up better.

Mr. Jones, I commend you on your patience & methodology. Both on how you h andled this thread, as well as your experiments with your steps.

I am disappointed however, that you have never posted the results/findings of your investigation. Although I can hardly blame you based on replies & feedback you were getting from other posters. But I would appreciate very much for you to kindly share what you have learned.

You express yourself clearly & concisely, your questions are valid & pertin ent and your logic has been sound. You have a genuine thirst for knowledge & a hunger for the truth. You are not ego-driven like nearly all of those who commented on your question (I can't say "answered" because none did, a nd even saying "responded" seems to imply more relevance & substance than m ost posts contained)- you were merely seeking information, which in the end you were able to obtain on your own. It is rather disturbing how poor the average/typical levels are for such ba sic skills as reading, comprehension & short-term memory, which this thread exemplifies. It's baffling to me why everyone seemed to get so worked up, trying to turn it around & criticize the question or you- even resorting to swearing & name calling all because THEY were unable to answer your questi on or even provide any truly useful, pertinent information. People can be so ridiculous, silly & ignorant.

In any case, thank you! I found the information you shared very helpful and informative.

!!!LOOK AT THE DATE!!!!

I agree with Jonpa..., most of the information was useful and informative. The posters replying to the thread didn't seem to grasp the idea of what was being discussed, and offered little in that direction.

Mineral spirits? Gasoline? Just follow the directions? The reason for using primer in the first place is to fill in the bumps, creases, and other imperfections on the bare wood. The same is true of the primer you spray on your car's body to avoid rust.

My problem isn't decking, mine is beehive lids that absorb huge amounts of moisture from the respiration of the bees clustering in winter. The wet wood lifts the paint and flakes it off. Acrylic primer doesn't seem to work at all.

As for the date, we're aware of it, Philo. We're wishing for a followup to the experiment concerning the thinned paint as a primer substitute.

Quilt boxes . That is , a shallow tray above the cluster that's filled with wood shavings or other absorbent material . Do you have an upper opening for warm moist air to escape ? If not , I'm surprised you don't have cold water dripping on the bees , a sure way to kill a colony . I use an inner cover with an outer that's covered by aluminum flashing , no paint on my covers .

The funstion you are referring to is the filler. A "primer" enhances adhesion of the paint to the substrate. Thinned latex isn't much good for either.