Posts Tagged ‘moisture’

Strange Bubbles in Drying Wallpaper

September 21, 2021
Air bubbles appearing as this wallpaper dries.
Smoothing brush, and plastic smoother.

It’s not uncommon for vinyl wallcoverings to develop bubbles as the paste dries. This is called “off gassing” and it happens because the vinyl is impenetrable and there is nowhere for air to escape.

But these days, most paper products – such as this one – allow air to pass through, and dry nice and flat with no bubbles or blisters.

One thing to keep in mind is, virtually always, these bubbles will disappear as moisture evaporates and the the paper and paste dry and shrink taught. So the less fiddling you do with it, the better. (And exception would be large bubbles, which should be addressed.)

One way to treat bubbles is to chase them out toward a seam, using a tool such as the plastic smoother. You can also use a pin or razor blade to poke a tiny hole in the paper to let the air escape. It helps to do this in a part of the pattern, and not in an unprinted area, to disguise the hole.

I also like to understand why something like this happens. If you know what caused it, you have a chance of preventing it the next time.

I primed the wall with my usual primer, so I don’t think there would be issues with moisture being trapped between the primer and the wallpaper. But then again, you never know what is inside the wall – many walls have been painted multiple times, and some layers may not be compatible.

Another cause could be the plastic scraper. The bristled smoothing brush uses a more gentle action to push the paper into place. The scraper could actually overwork and stretch the paper. In fact, if you use the scraper to try to push bubbles out to a seam, you end up creating more bubbles.

I use the plastic smoother mostly for seams, and not so much for smoothing a full strip into place. But it’s possible that I used it more than usual this time, and stretched the paper, creating conditions for the bubbles to form. In fact, on one strip, I gently pulled the bottom portion away from the wall and then put it back in place, but making sure to use only the bristle brush. This did eliminate the bubbles.

But, again, if you just wait it out until the paper becomes thoroughly dry, nine times out of ten, all the bubbles will be gone by morning.

Paint Pulling Off Wall Where Tape Was Removed – Surface Stability Test

May 12, 2021
Paint pulling off wall where tape was removed.
Paint pulling off wall when painters tape was removed.
Paint pulled off wall and stuck to back of tape that was pulled off wall on new construction site.

It’s important to have a stable surface under wallpaper.

That’s because, when wallpaper gets wet with paste, absorbs moisture from the paste, and it expands. Then, as it dries, it lets go of the moisture and shrinks. When wallpaper dries and shrinks, it puts tension / torque on the walls.

If the surface under the wallpaper is not stable, the tension of the drying wallpaper can cause the underlying surface to pull away.

This photo is not showing the wallpaper pulling away from the wall. What is happening (usually) is that the paint (or whatever has been applied to the wall), has actually delaminated (come apart) from the wall.

This results in a “curled” seam, or a “popped” seam.

One way to test for this is to apply a strip of tape (blue painters tape, tan masking tape, clear Scotch tape, or other), let it sit a few minutes, and then yank it off. If the tape takes any paint along with it, you have a potential problem of the wallpaper not adhering correctly.

This is why it’s important to:

1, Before applying any coating, you must remove all dust from the wall, using a damp sponge, which must be rinsed frequently

2, Before hanging paper, a primer formulated specifically for wallpaper should be applied / rolled on and cut in to edges

A wallpaper-specific primer is designed to withstand the torque put on the wall as wallpaper dries. And it facilitates installation by allowing sufficient “slip” (maneuvering the paper) and “stick” (adhesion). The chemistry behind all this is fascinating – but too complicated to get into here.

If a wall is too “iffy,” and you don’t feel like the mess and expense of scraping off all the old paint, a liner can be applied before the actual wallpaper is hung.

A liner lessens the drying time of the wallpaper, which reduces the time there will be stress on the wall. A liner also redistributes stress on the wall, so much less chance of having seems detach from the wall.

A liner also adds additional cost to the job – for both material and labor, which may include an additional day(s).

Whoops! Someone Painted Over Old Wallpaper

April 21, 2021

Just looking at the walls, I had not noticed . But when I removed the light switch cover, it was clear that someone didn’t bother to remove the old wallpaper, and just painted over it.

Actually, they probably did do some prep, because you could not see seams under the paint. They must have taken steps to cover the seams.

And there was no flashing … difference in texture between paint over wallpaper, for instance, and paint over smoothing compound that was used to disguise those seams.

And there were no bubbles (caused by latex paint on top of wallpaper that absorbs moisture from the paint and swells) and only a few tiny loose areas.

Still, it would have been better if the previous guy had put some effort into removing the wallpaper, and then washing the paste off the wall and then sealing with a stain blocker, to prevent paste residue from causing the new paint to crackle and flake off the wall. Then the room would be adequately ready for paint.

Minor Bubbles, Waffling, Quilting on Wallpaper

March 28, 2021

A lot of high-end wallpaper manufacturers use heavy inks (a.k.a. stinky ink). When wet paste is rolled on to the back of the wallpaper, these inks commonly compete with the substrate for moisture. The substrate absorbs more moisture and more quickly than the inked areas.

The result is wrinkles, blisters, bubbles, warps, quilting, waffling – whatever you want to name it, you’ve got a bumpy surface that doesn’t want to lie flat on the wall.

One way to tame this beast is to LIGHTLY sponge water onto the surface of the paper, before pasting. This allows the front to absorb moisture at the same time that the backing is soaking up moisture from the paste. The result is a more even “quilting” of the material.

Another thing to keep in mind is that small blisters like seen in the photo will usually flatten out and disappear as the wallpaper paste dries. A good wallpaper-specific primer underneath is a big help.

Also, a liner paper is often a good choice. The liner is a special, unprinted paper that goes under the decorative wallpaper. The liner absorbs moisture quickly and helps “lock down” bubbles and seams.

A liner also ups the installation price. Because you have to add the cost of the material, plus the labor of at least an additional day to hang the liner, and then let it dry at overnight or longer.

Challenges With 40″ Wide, Thin Vinyl Mural

March 13, 2021

See other recent post(s) for more info on this material and its install.

When ordering, from the materials offered, the homeowner chose this vinyl option, because she loved the slightly textured, “pebbled” surface. I would have much preferred she went with the more predictable and cooperative non-woven material.

The instructions said to paste the wall. Which is what I did. But I believe this material would have performed better if they had said to paste the product.

Pasting the product would have evened out moisture absorption from the paste, as well as expansion as the substrate wetted-out. That may well have eliminated the wrinkles you see in the photo.

It took a lot of patient work with both the smoothing brush and the plastic squeegee to work these wrinkles and bubbles out of the wallpaper. The resulting flat surface was not necessarily the Holy Grail … because often the far edge of the wallpaper will get distorted and / or warped / bowed.

It’s really difficult to hang a new, subsequent strip next to a strip with a warped edge. It’s hard to butt the seams, and plus additional strips get more and more warped. Eventually, you get to where the resulting wrinkles are so large that you cannot work them out.

This is one reason why you start hanging from the midpoint of the wall. This helps disperse any such wrinkles or other imperfections equally across both the right and the left sides of the wall.

I was lucky that I had only four panels and three seams on this install.

As mentioned above, a non-woven substrate would must surely have eliminated the wrinkle problem. Non-wovens are made of synthetic fibers (including fiberglass), so they do not expand when wetted by paste or water. So you can paste the wall and then apply the wallpaper, without worries about the paper stretching out of shape

Why Are These Seams Pouching Up?

November 4, 2020

There are a couple of issues going on in this master bathroom, causing the wallpaper to curl at the seams and the layers to delaminate.

For starters, the previous installer did not bother to remove the original wallpaper, but hung on top of it. He did prime over the original wallpaper, which is good,,,, but that primer felt too slick to provide a good surface for the new wallpaper to stick to. I have a feeling it was not formulated for wallpaper.

Second, there has been a lot of steam and humidity in this room over about 15 years. This particular type of paper does allow moisture to find its way into the seams, causing curling and delaminating.

These pre-pasted, paper-backed, solid vinyl wallpapers are among my very least favorites.

Read more about this material by clicking the link below.

https://wallpaperlady.wordpress.com/stay-away-from-pre-pasted-paper-backed-solid-vinyl-wallpapers/

Mirror Tar Bleeds Through Wallpaper – Prevention

June 18, 2020



The owner of this newish home in the Woodland Heights (Houston) had her handyman remove the powder room mirror and its surrounding built-in wooden frame. Mirrors are often adhered to the wall with mastic, a tar-like substance. When the mirror comes off, some of the tar residue invariably remains.

In the top photo, you can see where removing the mirror took the blobs of mastic along with it, as well as round sections of the drywall. But there are small smudges of tar still remaining on the wall.

The problem is that tar (among a lot of other substances) will bleed through wallpaper (as well as paint, and a lot of other materials).

There are stain blockers like my beloved KILZ Original Oil Based, BIN shellac based, or others, that are designed to block these stains. But I don’t trust them. For water, rust, blood, wood sap, etc., yes. But for oil-based substances like tar, I want more assurance. The best way to prevent bleed-through is not to cover the stain, but to remove it.

So I take a Stanley knife and cut into the drywall and then peel up the top layer of drywall, taking along the offending tar residue.

So now the dangerous tar is gone. But you’re left with torn drywall. This is bad for several reasons. For one thing, you have an uneven surface that will look bad under the new wallpaper (or paint). And since the top, protective layer of drywall is gone, any moisture (such as from wallpaper paste or from latex paint) will penetrate into the torn paper layer – which will swell and cause bubbling.

All of which looks pretty bad under wallpaper or paint.

So I used the product Gardz to seal the torn drywall. It is formulated to soak into the paper; then it dries hard and acts as a sealer and moisture-blocker. It won’t block stains, but it will prevent moisture from penetrating the paper and causing bubbling.

Once that was dry, I skim-floated over the entire area with joint compound. It looks rough in the photo, but once it’s dry, I’ll sand it smooth. Then I’ll give it another coat of the penetrating sealer Gardz. See last photo. Once that is dry, I’ll cover it with a coat of Roman’s Ultra Prime Pro 977 wallpaper primer, when I prime the other walls in this powder room.

All of these various products do take a while to dry, especially the joint compound as thick as I applied it. So I went to this job site a few days before the install date, to do the initial prep, so it would have plenty of time to dry before I come back for the final prep and wallpaper hang.

Spoonflower – Overlapping Seams

April 5, 2020


Re my previous post … this manufacturer, Spoonflower, specs that the seams on its wallpaper should be overlapped – by as much as 3/4″.

On a busy pattern, you might not notice this. But when there is lot of blank space (white area), and when light is coming at an angle (see photo), you’re might notice it.

If you hunt, at every seam, you can spot a ridge the height of the wall, that’s about 3/4″ wide. To me, it’s not much of a big deal. Once yo uget used to it, you don’t even notice. In fact, I have authentic 1930’s and 1940’s wallpaper in two rooms of my home – with overlapped seams – and it doesn’t bother me in the least.

Truthfully, overlapping seams actually has many advantages. For one thing, when wallpaper gets wet with paste, it absorbs moisture and expands a little. Then when it dries, it can shrink a little. This is how you end up with tiny gaps at seams.

Second, overlapping the seams can reduce stress on the wall surface, and prevent the layers within from delaminiating, which can cause popped seams. (Do a Search here on “delaminate” for more info and pictures.

Bibliotheque Install Details, Pt III – Curling Edges

March 18, 2020

As mentioned in a previous post about this install, wallpaper paste introduces moisture to the back of the paper, which causes the backing to absorb moisture and expand – and, sometimes, as in this case, the expansion will cause the paper to curl back on itself.

As you can imagine, this makes it a whole lot harder to get the strip positioned and secured to the wall.

Reattaching Curling Seams on Vinyl

January 7, 2020


I hung this Bankun Raffia woven fabric-backed wallpaper a few years ago. Some of the edges along the tile and over the shower and below the window had begun to curl. This is mainly due to

` Not wanting to adhere to the porous tile grout
` Humidity from the shower
` Moisture inside the wall, or coming through the window frame

The few areas that had an inch of paper that was loose called for wallpaper paste. But for the very edges, my “secrete weapon” of clear silicone caulk was the solution. Caulk is tacky and grabs more quickly than wallpaper paste. And it will hold tighter against the aggressive curl of the vinyl.

That aggressive curl is a bit of a beast. But I have another “secrete weapon” that is up to taming the beast – a heat gun.

Be careful using it, and practice first, so as not to damage the vinyl. But judiciously applied heat will relax the vinyl just enough that it will release its curl and lie back neatly into it’s original position against the wall.

In the picture, the putty knife is for pulling the loose edges away from the wall so I can get paste and caulk behind the paper. The white smoother is for pushing the paper against the wall. The putty knife was also a good option here, because it withstood the heat of the heat gun better than the plastic smoother.