Priming/Sealing drywall before wallpapering

[Percival P. Cassidy]

I had read that new drywall needs to be primed/sealed before trying to apply wallpaper; "Shieldz" was mentioned specifically, so I bought a qt. can of clear Shieldz (it's a small area). After applying one coat I checked online to see how long I should wait before applying the paper, only to find that they say that for use over mudded drywall I should use the white Shieldz -- but although it's made in quart cans nobody sells it in quart cans.

Is there a good substitute that might be available in quart cans?

Perce

[HeyBub]

I don't think any particular primer is necessary. The purpose of the sealer is to seal the drywall so it doesn't suck the moisture out of the wallpaper paste before it can adhere properly.

I sanded down one wall in the Great Room (formerly known as the "living room"). Nasty job, but it got rid of the drywall texturing. I then painted the wall with two coats of some white latex paint I had on hand. This served as the basis for a thirteen-foot mural wallpaper, constructed out of ten panels.

In your case, you already have one coat of sealer. Try slapping a piece of wet paper on the wall and see, after twenty minutes or so, whether the wall has absorbed any moisture. If not, you're good to go. If the wall is soggy or wet, another coat of something (Kilz, sealer, paint, etc.) is indicated.

[Percival P. Cassidy]

The surface still feels rough, not as though it has been sealed at all: no smooth film on the surface. The composition of the two kinds of Shieldz is totally different.

But I will try your suggested test.

Perce

[Colbyt]

To facilitate the removal of the paper in the future all surfaces should be primed with an oil base primer. Failure to do so will result in damage to the drywall when the paper is removed EVEN if it says strippable.

Tinting the primer to the same shade as the paper background will help hide the seams for darker papers.

[HeyBub]

Why oil based? Latex, or water-based, paint is waterproof when it dries.

[Colbyt]

That isn't my understanding of latex paint. Maybe marginally in the gloss type.

[krw]

There is a *lot* more to it than that. If the drywall isn't sealed before applying the wallpaper, good luck on getting it off without destroying the drywall. DAMHIKT.

[krw]

It is true. Flat paint may "chalk" some, but latex paint isn't water soluble, when dry.

[dadiOH]

Which does not mean it is not water permeable. Solvent paints are less permeable than latex.

[HeyBub]

I agree that oil-based paints are more secure against water, but if latex paints were all that permeable, there wouldn't be a market for latex-based exterior paints! Heck, if latex exterior paints were not immune to water, everybody in California would be screwed.

No, wait...

Never mind.

[krw]

It's not. Ask a firefighter. Often, after a fire water, is bulging behind the paint, like a water balloon. Latex paint is essentially a rubber glove that goes on liquid. You know, a *latex* glove?

[Papa Pat]

A little late, I know.....but, there is a product called "size", for all types of wall coverings and new or old drywall...

Go to your friendly paint store guy and tell him what you are doing...Then buy a quart of "sizeing liquid." Apply two coats, let dry between coats. Hang paper. Done..!

The primer size will allow you to move the paper on the wall and will not dry up on you before you can position it to where it needs to be. Also will allow wall covering to be stripped off when you get tired of looking at it...

[dadiOH]

You should let Sherwin-Williams know immediately as rhose dolts say...

Q: Do acrylic latex primers and topcoats "breathe" to allow moisture vapor to pass through? Does this breathability diminish when a second topcoating and subsequent repainting is done?

A:Studies have shown 50 gallons of water is vaporized into the air of an average home each day from cooking, bathing, laundry and people. Much of this moisture passes through the walls. If the exterior coating traps moisture, blistering and peeling will occur.

Moisture vapor is more likely to pass through acrylic latex paint films than through solvent alkyd types.

It's true that application of additional coatings will reduce moisture vapor transmission, simply on the basis of increased film thickness. However, even with several coats applied, the latex film will be adequately permeable to water vapor and better than alkyd paint films of comparable thickness.

Note that water and water vapor are two different things. But both are "moisture".

[Norminn]

clipped

Latex/acryllic is slightly more permeable than alkyd; found that out when we had our stucco/c.b. condo painted. Web sites for paint co. will bear that out. FWIW, I don't recall seeing alkyd primer for new drywall...all I can recall has been latex.

[Robert Macy]

Is that water vapor FROM 50 gallons of water evaporating, or is that

50 gallons of water vapor, whatever that means?

[krw]

Completely different thing.

Sizing is essentially a thin paste, used to make it easier to hang the paper. It is *NOT* a replacement for a sealing coat of paint.

Right, but without priming and painting the wall before, sizing won't protect the wall from disintegrating when you take the paper off.

[krw]

It's got nothing to do with vapor.

Irrelevant.

More irrelevant nonsense.

Now, say something relevant to the discussion.

[krw]

It's made. After my "experience" with paper applied directly to drywall, I used a shellac based primer under latex. It "eggshelled" terribly. The BM paint guy said that shellac was much too hard, making the surface too brittle (for a moist location), causing the paint surface to crack. The fix was an oil based primer and then another coat of paint. PITA, but worked beautifully.

[gramps]

So, information like this, which is all over the net, is incorrect?

"The truth of the matter is that sizing is a process that allows wallpaper to be installed with ease and at the same time allows it to be removed at some future time with little or no effect on the wall substrate."

[krw]

It's too bad you're illiterate but here, I'll try to help anyway:

"Wallpaper adhesive can bond to drywall paper. Drywall that is not primed ^^^^ ^^ ^^^ ^^^^^^ and sized properly will absorb these adhesives and tear. Drywall repair may be necessary."