Posts Tagged ‘moisture’

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.

Dark Papers – Visible Seams

September 10, 2019


Wallpaper is paper, and when paste is applied to the back, the paper gets wet and expands a little. When it hits the wall, it dries – and often that means it will shrink, even if just a tad. That will leave minute gaps at the seams. If the paper is dark and the wall or the substrate are light , you will most likely see white gaps at the seams.

Some manufacturers combat this by printing dark patterns on a darker substrate. This is what you see in the photo above. But it also helps to color the edges of the wallpaper with a corresponding color of chalk. (You can’t use ink, because ink will bleed and discolor the wallpaper.)

Sometimes you can go back and color in the seams with hobby paint or chalk, which sounds simple but actually takes some technique and finesse, to color the areas adequately and avoid staining the paper.

Painting the wall the color of the paper is a thought, but not as feasible as it sounds, because wallpaper wants to stick to wallpaper primer, not paint. And I’ve seen paint lift off the wall when the wallpaper dried and put tension on it – so, not using that trick again.

Paint with a clear wallpaper primer over it is another idea – but it adds an extra day (or two) and more labor and material costs.

What I did in this case, was to try different pasting methods. This wallpaper, from the Historic Homes Collection by Thibaut, is pre-pasted and engineered to be run through a water tray to activate the paste on the back of the paper.

This method works super with most of their colors. But, because the water tray adds a lot of moisture to the wallpaper, the amount of expansion and then shrinkage results in tiny gaps at the seams – not a big deal with a white or light-colored wallpaper. But with this black paper, it was showing too much white at the seams. Yes, a 1/64th” is too much, when you are looking at white between black.

So instead of running the paper through the water tray, I experimented with pasting the back of the paper. I knew this method would allow the paper to expand less, dry faster, and shrink minimally.

But wallpaper that has a thin layer of pre-paste on the back does not respond well to the installer applying paste to the back on top of the pre-paste. You are greeted with a thick, dry, gummy mess that is hard to manipulate on the wall.

There were also a lot of bubbles and blisters under the surface. Yes, you can be assured that these will disappear as the paper dries – but it sure makes you nervous while you are looking at them!

Spraying the back of the paper with water from a mister didn’t work, either, because the spray bottle spread water unevenly, water sloshed onto my work table, and there was nothing to enhance the “stickiness” of the manufacturer’s pre-paste.

After experimenting, what worked best was to apply paste to the back, full strength, and then quickly spritz the back with water and roll it around, to thin down the paste I had just applied, and to add enough moisture to activate the pre-paste.

The wallpaper strips with this pasting concoction were thick and muddy and difficult to maneuver, but the drier paste did lock down at the seams more quickly. I didn’t have issues with shrinking or gapping seams after I started using this pasting method.

Humidity in Bathrooms – Not Good for Lower-End Solid Vinyl Wallpapers

June 7, 2019

People often think that vinyl wallpaper will be good in a bathroom, because water will roll off it. but in reality, very little water gets splashed on the walls – but a lot of moisture can get wicked into the seams.

These photos (you may want to scroll to enlarge them) show how the lower-end, paper-backed, solid-vinyl wallpapers tend to perform poorly in humid rooms like bathrooms. The problem is that moisture gets in between the seams and into the paper backing. That backing absorbs moisture and expands, curling away from the wall. The backing can actually go a step further and delaminate from the top vinyl layer.

This type of paper often performs like this when you’ve got people taking steamy showers, forgetting to turn on the vent fan, forgetting to keep the door open for air circulation, etc. Neither of these situations can be fixed. You will be stuck with these slightly curled seams.

The thing is, there are plenty of nice, paper or non-woven wallpapers out there, that will hold up a lot better in bathrooms.

Do Bubbles Mean Trouble?

May 20, 2019

The walls in this dining room in a historic house in the Houston Heights had received many coats of paint over its 100 years. The latest was a coat of what appeared to be flat latex paint. Since this is not a suitable surface for wallpaper, I applied a wallpaper-specific primer.

I was surprised to see that, a few minutes after I rolled on my water-based wallpaper primer, blisters appeared.

I thought they would disappear as the primer dried, but they did not.

Obviously, the moisture in the primer was soaking into some of the layers below it, and causing something to expand and “off-gas”, which created the bubbles.

I switched from my wallpaper primer to a penetrating sealer called Gardz (also water-based) – and the same thing happened. (The Gardz dried so glossy that I feared the wallpaper would not stick to it, so I went back to my original Ultra Prime by Roman’s.)

Once the primer was good and dry, I used a stiff putty knife to knock off the high points of the blisters. The areas were not perfectly smooth, but they were OK for use under this particular wallpaper.

I’m doing some research, and am hoping to gain insight as to why this blistering happened, so I’ll know how to prevent it in the future.

Low End Wallpaper – Not So Bad This Time

October 12, 2018


I’ve said it before – these budget-friendly, pre-pasted, manila paper-baked solid vinyl wallpaper products are generally not good quality, and the Norwall brand is about at the bottom of the list. In fact, I often will decline to hang it. Do a Search here on those terms, or click the Page to the right “Stay Away From … ” for more info.

However, this homeowner, a Meyerland neighborhood (Houston) victim of the Hurricane Harvey flooding, and a client for whom I had worked back in the ’90’s, really loved the pattern, as well as the price-point. And she wanted her entry to look as it had before the flood ravaged her home.

I was pleasantly surprised. The paper went up OK, and the seams looked fine. It’s possible that the company has improved its product. But it’s more likely that my new installation method helped.

Instead of following the manufacturer’s instructions to run the paper through a water tray, which makes the material too wet and promotes bubbling, and instead of pasting the back of the paper, which turns it into a gummy mess, I tried something new. I used a spray bottle to lightly spritz fresh water onto the back; this activated the paste, but was not so much water that it would cause bubbling or seam curling or over-expansion of the material. I booked the paper and put it in a black trash bag to sit a few minutes.

Next I rolled paste onto the wall. I started out using a very faint coat, but found that a tad more worked better. I used a brush to cut the paste into the edges and around the floor and ceiling.

When I took the very slightly dampened paper to the wall and smoothed it against the lightly pasted surface, it adhered very nicely. It was pretty easy to smooth into position, although there was some twisting of some strips, which could have been a problem in a room that required more strips next to one another.

Usually these inexpensive vinyl papers grow bubbles, because, as they dry, there is nowhere for the moisture to go (because it can’t pass through the vinyl surface), so blisters form. But today was very little bubbling.

Best of all, the seams looked good. I didn’t get any of the raised edges that are so unattractive, and that allow moisture / humidity to penetrate and cause the backing to swell and pull away from the wall.

I am not saying that I was happy with this paper. But it was a lot better than I expected. And I hope that it will continue to look good for years to come.

Mildew on Wall Indicates Moisture Problem – Somewhere

October 9, 2018


I have just stripped off a solid vinyl wallcovering that had been up for at least 10 years, possibly twice that. The entire wall was covered with mildew. The mildew was present just on the exterior wall; not any of the walls that connected to interior areas of the home.

Mildew breeds when there is moisture. This indicates that there may be a leak in the home’s siding, or a leak in a window on an upper floor allowing water to get inside the wall and into the drywall. Another possibility is that plumbing inside the wall could have sprung a leak, and also caused the drywall to become wet.

Because the wallcovering was solid vinyl, it trapped the moisture between the wall and the wallpaper, and that allowed mildew to grow between the two surfaces. I’m rather surprised that the mildew didn’t penetrate through the wallpaper and show on the surface. The drywall didn’t appear to be soggy or rotted or compromised.

Another reason why I don’t like solid vinyl wallpapers.

Hoping to Rectify Failure (Humidity Causes Poor Seams)

August 24, 2018

Humidity is the great enemy of wallpaper. In addition, the lower-end, pre-pasted, solid-vinyl papers with the gritty manila paper backing are not a good choice, in my opinion, in any room, but particularly not humid rooms like bathrooms. This house on the beach with irregular climate control spelled double trouble.

This home on Pirate’s Beach on Galveston Island (south of Houston) was on the beach, so was exposed to lots of humidity. In addition, because the homeowners use it only sporadically, they turn the air conditioner off or set it to a run less while they are away. This means that the home fills up with humidity. And even when the A/C is running, air circulation in this room is poor.

Metal elements such as the light fixture and screws holding things into the walls were rusted. Mildew was found behind some sheets of wallpaper. And the wallpaper itself was curling at the seams – a result of the paper backing absorbing moisture from the air, expanding, and forcing the vinyl surface to curl backward at the seams. (Read more about this on the page to the right about vinyl wallcoverings.)

Another factor for the poor performance of the original vinyl wallpaper was that the walls had not been primed, but the installer put the vinyl paper on top of new drywall. And nothing was done around the shower to protect the paper from splashing water.

I stripped off the old vinyl wallpaper, washed the walls with bleach to kill the mildew, and primed with the penetrating sealer Gardz. Once the new paper was up, I ran caulk along the top of the vanity backsplash, and all along the shower and tub, to prevent splashed water from wicking up under the paper.

The new wallpaper is a thin non-woven material that is “breathable.” No wallpaper is going to hold up under very humid conditions. But this one has a much better chance of staying nice and flat for many years.

The new wallpaper is very similar in appearance to the original, and keeps with the beachy feel of the home. It is by Brewster, in their Chesapeake Bay collection, in the Easy Walls line, and is reasonably priced. It is a pre-pasted material. I did augment the manufacturer’s paste with a .

In the photos, the paper looks blotchy. That is because it is still wet; it will be nice and white when it’s finally dry. The drying time worries me, though, because after six hours, even some parts of the first strips were not dry. This is a real indicator that the room has some serious humidity and air circulation issues.