Posts Tagged ‘expands’

Tape Test for Unstable Walls

September 21, 2022

There can be reasons for unstable walls, mostly cheap or poor quality paint, dust, someone applied paint over dust, improper prep, incompatible layers inside the wall built up over years (oil based paint, latex paint, dust, gloss paint, joint compound, etc.).

These can cause problems with wallpaper, mostly with the layers delaminating (coming apart), which causes the wallpaper seams to come away from the wall. Sometimes sheets of wallpaper simply fall off the wall.

This isn’t so much a problem with paint, because it just sits on the surface. But wallpaper shrinks when the paste dries, or expands and contracts with humidity, and can put tension on the seams

Before wallpaper goes up, one way to test for such unstable surfaces is the tape test . Use a razor blade to cut an “X” into the wall, scoring through the paint and maybe into a few layers beneath. Place a strip of blue painters tape over the cut. Pull the tape off the wall.

If paint comes away from the wall along with the tape, or if layers inside the wall come apart, you know you have to do a lot of specialized prep to stabilize the wall before hanging / installing the wallpaper.

This example is an interesting twist. The homeowner used a piece of tape to hold up a wallpaper sample. Then used an ink pen to write notes on it. When removed, the tape took the paint off – in the shape of the writing!

Dark and Moody Bedroom Accent Wall

August 4, 2022
The wall has been skim-floated and sanded smooth , primed , and is ready for wallpaper .
The homeowner did a great job coordinating the wall and ceiling paint with the colors in the wallpaper.
This is a room that’s made for sleeping!

At first I thought the pattern scale was too small for the large wall. But once I saw it on the wall, I really like the way it fills the space.
To me, this pattern has a sort of calico look.
Close-up shows the light texture on the paper.
This is a non-woven material, so I’m installing via the paste the wall method . Here I’ve cut and arranged all my strips in the order in which they will be hung . This is a drop match pattern , which some folks think of as A and B strips. Meaning, for instance, an orange flower appears at the top of the wall on Strip A . But the next strip, Strip B, has a yellow flower at the top. When you get to the third strip, we are back to an A and an orange flower. Next comes another B strip – and so on.
I’ve rolled the strips backward , with the top of the strip coming off first. This will prevent the printed face of the wallpaper from bumping into the pasted wall during installation .
Wallpaper often shrinks a tad when the paste dries , and this can result in very minute gaps at the seams . With dark wallpapers , it’s pretty important to take steps to prevent white from showing at these gaps. Here I’ve measured out where each seam will fall, and taken diluted black paint to make a dark stripe under each seam . I don’t make the paint full-strength, because wallpaper paste isn’t formulated to adhere to paint. I want the wallpaper adhering to the primer I’ve applied. That’s also the reason why you don’t want to roll paint over the whole wall.
Also, I have only striped some of the seam areas, and will wait until some strips are up on the wall before striping more lines. This is because wallpaper expands when it gets wet with paste, which can make it difficult to plot the exact width of each strip as you move across the wall.

I use acrylic craft paint from the hobby store, applied with a bit of sponge. I keep a small dish of water to dip the sponge into, which dilutes the paint a bit.
You also see a stick of chalk pastel . See next photo.
Besides the wall peeking out from behind the wallpaper seams , it’s also possible / probable that the white edges of the wallpaper backing / substrate will show at the seams. I take a stick of chalk and run it along the edges, making sure to apply from the backside, to avoid getting chalk onto the surface of the wallpaper.
Be sure to use chalk pastels and not oil pastels – oil will bleed and stain wallpaper. Some installers use liquid paint or markers – again, be sure to use water-based or acrylic , and never oil based or permanent markers .
BN Walls is the brand. Altogether, this was a pretty nice product to work with. It was thin and very soft and flexible (many non-wovens are not).
I wasn’t happy with all the seams, though. I believe the paper was cut with dull or wobbly wheels at the factory, because the edges seemed to not be perfectly straight . So I ended up with gaps and overlaps in some areas. Here you can see the wallpaper edges pouching up a bit due to excess paper.
But, as I mentioned, this material was quite flexible, so it was pretty easy to spread these edges apart an use a tool to push them apart and then down to prevent them from pouching up again. Once the paste started to dry, these areas held nice and tight and flat.
This is a townhome in the Rice Military neighborhood of central Houston .

Dwunk Cwitters – Dark Seams

July 29, 2022
Re my previous post , it’s very common for wallpaper to shrink just a tad when the paste dries, and this can leave you with teeny gaps at the seams. So when hanging a dark paper like this, I like to stripe a band of black paint under where the seams will fall. This way, if the paper does gap at the seams, you will see dark, and not the white wallpaper primer .
I measure and plot where each seam will fall and then run a stripe of diluted water-based craft paint (from Michael’s or Texas Art Supply) under where the seam will be. I wet a scrap of sponge and dip it in the paint, adding water as needed. Don’t make it too thick or dark. Because you want the wallpaper adhering to the wallpaper primer underneath all this.
On top of the wallpaper primer, the craft paint dries pretty quickly. But I use a heat gun to be sure the paint is good and dry before hanging each strip.
Don’t paint more than one or two stripes at a time, because wallpaper stretches and expands when it gets wet with paste , and it’s difficult to predict exactly where each seam will fall. For the same reason, be sure your stripes are at least 1/2″ wide, if not a full inch.
Additionally, I’ll take a pastel chalk (NOT an oil pastel – oil stains wallpaper) and run it from the backside along the white edges of the wallpaper, to prevent any white edges from showing at the seams. Do a Search here to see previous posts about that trick .

More William Morris Strawberry Thief in Houston Heights Hall Bathroom

June 24, 2022
Because I feared unstable walls in this 1920’s bungalow in this neighborhood (do a Search for previous posts), before hanging the decorative wallpaper, first I hung a non-woven liner paper on all the walls. That’s the white material you see in the photo.
The liner was hung horizontally so its seams can’t line up with the decorative paper. The idea is to disperse tension from drying wallpaper and changes due to humidity and etc., so as to deflect tension away from sketchy wall surfaces, and thus prevent delamination of multiple unstable layers deep inside the wall. Again, do a Search here to learn more.
Finished vanity area, with pattern centered on the light fixture.
Corner shot.
This colorful and symmetrical pattern is quite popular; I’ve hung it a number of times just this year.
Englishman William Morris designed wallpaper and fabrics during the late 1800’s and early 1900’s.
The styles then were Art Nouveau and Arts & Crafts. This design reflects a bit of each.
Wallpaper expands when it gets wet with paste, and then can shrink just a tad as it dries. The liner helps prevent that, but you can still end up with teeny gaps at some seams.
To prevent the white backing from showing through, I run a stripe of dark paint under where each seam will fall.
I use matt finish craft paint from the hobby store, diluted with a little water (in the orange bottle cap) and smeared on the wall with a scrap of sponge. Use a ruler or level and a pencil to mark where you want to stripe the dark paint.
Remember to allow for that expansion as the paper absorbs moisture from the paste. Meaning, if the paper is 20.5″ wide, and expands 1/2″, you’ll want to run your line at about 21.” And make sure that your painted swath is about an inch wide.
I also run a bit of dark chalk along the edges of each strip, to prevent the white substrate from showing at the seams (no photo).
Morris & Co. makes this iconic Strawberry Thief.
Interestingly enough, most times when I’ve hung a Morris paper, it’s been a non-woven paste-the-wall material.
Today’s option was a surprise – a traditional British pulp . This is a pretty basic and somewhat old-fashioned type of substrate . Sort of like construction paper, or the pages of an old family Bible .
The paper is very fragile , and can tear easily. You have to keep using new razor / trimming blades, because the material dulls blades quickly, and when dull they will drag and tear the paper.
Pulp papers also require a soaking / booking time after pasting , to allow time for the material to absorb the paste , soften a bit, and expand . The edges of the strips like to dry out , so I’ve learned to dip about 1/4″ of the booked ends ( booked means the pasted side of the wallpaper strip is folded onto itself, bottom edge folded up and top edge folded down to meet in the middle), into a bucket of clean water.
Then it goes into a black plastic trash bag to soak and relax for a few minutes before hanging. I use this opportunity to paste the next strip.
Non-woven wallpapers have advantages, because they do not expand when wet, and therefor you can get accurate measurements. They also can be pasted and hung immediately, with no waiting time. Alternately, you can paste the wall .

Preventing White From Showing At The Seams

March 10, 2022
When wallpaper gets wet with paste, it expands a bit. And when it dries, it can shrink just a tad. That teeny gap at the seams can expose the wall underneath it. This can happen even with the non-woven materials, which are supposed to be dimensionally stable.
In addition, manufacturers usually print on a white substrate, so sometimes you see the edges of the paper at the seams, too.
All this is much more noticeable on a dark paper, such as here.
One thing I do to prevent / minimize this is to strip the wall with dark paint under where the seams will fall. So even if a seam opens up a bit, you’ll see dark, not white.
Since non-woven wallpapers don’t expand (much), it’s easy to measure the width of your strips and plot where the seams will fall, use a level, and then apply the paint.
I use plain old craft paint from the hobby store. I use a scrap of sponge and dip that in water (in my orange bottle cap) then into the paint, and then run my stripe down the plumb line I’ve drawn on the wall or used my laser level to shoot a vertical line.
It’s important to not get the paint too heavy or thick, because the wallpaper paste may not want to grab ahold of paint like it wants to hold on to a wallpaper primer. And definitely don’t use a gloss paint.
Be sure that it’s good and dry before you hang the wallpaper. A heat gun will speed things along if needed.
Not pictured, but you can look up other posts here … I also take a bit of chalk of a corresponding color and run it along the edge of the wallpaper to cover up that white edge. It’s important to apply the chalk from the back, to avoid getting any on the front of the wallpaper. Some colleagues use water markers, pencils, or gouache paint. Whatever you use, do not use anything with oil-based inks or colors. These will bleed and stain your wallpaper.
Chalking the edges is more important than striping the wall, IMO.
This pattern is called Allure and is by Graham & Brown , a brand I like a lot.

Fitting a Wide Strip into a Narrow Wall Space in a Corner

February 18, 2022
I have to cover 15″ width of wall with a strip of wallpaper that is 27″ wide. Working with that 27″ wide strip and pushing it into the corner, and getting paste all over the woodwork, and trying to not get creases in the paper … all very difficult.
My solution is to trim the wallpaper to fit the corner. Here the strip has already been cut, pasted, and booked (folded pasted-side-to-pasted-side). I’ve determined that I want the new strip to be 15″ wide. This will allow enough to cover the wall space, plus the 1/2″ inside the little space between the wall and the door trim.
Because wallpaper expands when it gets wet with paste, to get an accurate measurement, I’m trimming after the strip has been cut, pasted, and booked for a few minutes, and has expanded to its maximum.
This is called wet trimming. Alternately, dry trimming is when you measure and trim an unpasted and unfolded strip.
My straightedge is set at 15″ from the left edge of the wallpaper. I’ve used a single edge razor blade to make the cut.
Here is the strip in position on the wall. I’m using a plastic trapezoid squeegee wallpaper smoother to push the right edge into the small space between the wall and the door molding.
You can see how nicely the wallpaper wraps around the corner and tucks into that narrow space.
The pattern is called Garden Party and is by Rifle Paper, which is made by York, one of my favorite companies.

Preventing White Wall From Showing

January 23, 2022
Wallpaper expands a bit when it gets wet with wallpaper paste (3/8″ in this case), and then shrinks when it dries. This can result in the white edges of the paper showing, or the wall behind peeking out from teeny gaps. With a dark paper like this, it can be noticeable. I ran a piece of black chalk along both edges of the paper to cover the white substrate (no photo). It’s important to use chalk and not oil pastel, as oil will stain wallpaper.
Then, to keep the the wall from peeping through, I striped the area on the wall under where the seams would fall with black paint. Not shown, I used my heat gun to speed along the drying of this stripe. I don’t make the paint too thick, because you want the wallpaper seams sticking to the wallpaper primer, not to the paint.
All this takes a good bit of time. Also, it’s tricky to plot ahead, because, due to the expansion factor, it’s difficult to know exactly where the seams are going to fall. Non-woven materials don’t expand, but papers like this one will.
I use paint from the hobby store or Texas Art Supply, run along the wall with a small chunk of sponge, dipped in water.

Paint Stripes to Prevent White Wall Peeking Out

January 8, 2022
Sometimes (usually) wallpaper expands when it gets wet with paste and then shrinks just a tad when it dries. This can result in hair-breadth gaps at the seams. Usually not a big deal. But when the paper is dark and the sub-surface is light, you can end up with white wall visible at the seams.
So sometimes I’ll paint a stripe of matching color behind where the seams will lie. Measure to plot where the seam will fall, then use a level and pencil, or a laser level, to indicate where, and then run a stripe of paint along that line. Make the stripe wide enough to accommodate slight variations in measurements and wallpaper expansion.
I use craft paint from the hobby store or Texas Art Supply. The photo shows an outdoor paint – not the best option, but it’s what I had in the truck. 🙂 I use a small rectangle of sponge dipped in water and then in the paint.
For extra assurance, on thick papers, dark surface printed on a white backing, you can also use artist’s chalk pastels (chalk only and NOT oil pastels) to color the edges of the seams. Do a Search here (upper right corner) to find previous posts about that.

“Priming” Wall With Paste to Keep Seams Down Tight

August 3, 2021
Hard to see, but the slightly darker, shiny section of wall to the left of the wallpaper is a bit of paste that I have rolled onto the wall along where a seam will lie.
The paste has pulled the edges of the paper nice and tight to the wall. Never mind the slight pattern mis-match … this is a hand screen print, and it’s pretty common for these to be slightly off in printing and/or trimming. The pattern matched better above the door, then drifted off as the paper neared the bottom of the strip. You can also see that some of the edges are somewhat jagged and saw-dusty, due to trimming at the factory.

Some manufacturers use inks that fight with their substrates. The substrate absorbs moisture from the paste and expands, but the inked layer does not, so you end up with the bottom layer stretching and forcing the top layer to curl back, resulting in edges that curl and don’t stay tight to the wall.

Any time you smell ink that calls to mind mothballs, you can expect to deal with this issue. It’s pretty common with screen printed wallpapers.

One trick is to lightly sponge the surface with water before pasting the back. Another, which I have discussed here previously, is to paste the paper, fold and book it, and then dip the rolled-up edges into 1/4″ of clean water. Then place the rolled up strip into a plastic trash bag for the booking period. This helps to keep the edges from drying out while the paper books.

On many papers, I’ve found that it also helps to roll a light coat of paste onto the wall, just under where the seams will fall. This works amazingly well to grab the edges and hold them tightly against the wall.

Compensating Around A Window

June 29, 2021

Going around windows, especially wide windows, can be tricky. Wallpaper expands, it twists, the design can travel up or down from the ceiling line – and all this can go on independently of each other, with the sections over the windows moving out of whack at a different rate than the strips below the window.

The challenge then becomes, when the next full-length strip is hung, joining the strips over the window with those under the window … getting the pattern to line up and the strip to lie flat on the wall without torquing out of shape.

In this case, the pattern lined up pretty well. But strips under the window ended up being wider than those over the top. So there was a 1/2″ overlap, which would mess up the pattern match. This 1/2″ also caused the full-length strip to warp and develop a wrinkle.

This was an easy pattern and placement for dealing with such issues. All I had to do was cut along one of the palm tree stems, slide the strip up so the palm leaf pattern lined up, straighten out the full-length strip and work out the warp, and overlap that 1/2″.

All that sounds simple. But the truth is, I probably spent the better part of an hour getting it all to work out.