Posts Tagged ‘joint compound’

Patching Gap Around Light Fixture

November 8, 2019

The original light fixture had a rectangular base. The new one had a base that was barely larger than the electrical box. The electrician ended up with a slight gap on the left side of the box.

The wallpaper would most likely bridge that gap and look just fine. But since there was a slight difference in height between the wall and the base of the fixture, I wanted to close the gap to minimize chances of a visible pooch or bubble around the fixture.

I bought some drywall repair kits, and ended up using the one that had a thin aluminum mesh patch. I cut it to fit around the electrical box, using a few scraps to fill in gaps.

I then used drywall joint compound (“mud”) to smooth over the area. It took two of these skim coats, and a lot of time holding my heat gun to get everything to dry. Once sanded, it was nice and smooth.

A coat of Gardz penetrating sealer / primer, and the patched area was ready for wallpaper.

Elapsed time: Two hours.

This saved the homeowner having to hire “a guy” to do the repairs – and most likely, I would have had to “fine tune” whatever he did, anyway.

KILZ Stain Blocker to Cover Green Ink

October 26, 2019


See the green vertical line to the right of the paint can? The previous wallpaper installer probably had a little white wall showing at a seam, so used ink that matched the color of the wallpaper to disguise it.

Ink (along with other substances, like blood, rust, water stains, oil, tobacco, mildew, wood sap, and others) can bleed through joint compound, paint, and wallpaper. Sometimes it takes a few months or years.

So it’s important to discover these stains, and to treat them with a stain-blocking sealer. Water-borne products simply don’t work, no matter what the label claims. Shellac-based sealers like BIN are good. But I like KILZ Original, the oil-based version.

Knock-Down Texture on a Wall

October 3, 2019


Here is a new sheet of drywall, installed to repair damage from flooding during Hurricane Harvey. The drywall is grey.

The splats of white stuff you see on top is joint compound that has been sprayed on, and then “knocked down” to about a 1/8″ height by a worker with a wide taping knife.

This creates a texture on the wall that is pretty common in newer suburban homes.

The surface should be primed, and then a coat of paint can be applied.

In the case of wallpaper, the wall would have to be “skim floated” and sanded smooth, to get rid of the texture.

Getting Smoothing Compound To Dry

June 13, 2019


The walls in this powder room were textured. (see top photo) To ensure that the new wallpaper looks good, and that it has a solid surface to cling to, the walls need to be smoothed. This is called floating, or skim coating, and I do a lot of it here in Houston. To do that, I trowel on a plaster-like substance, let it dry, then sand it, vacuum up the dust, wipe residual dust off the walls with a damp sponge, and then prime.

What takes the most time is waiting for the smoothing compound (drywall joint compound, which we also call “mud”) to dry. If the texture is heavy, often it has to dry overnight. The downside of this is that it adds an extra day of labor and expense. But when the texture is lighter, the drying can be speeded along.

In the second photo, you see some of the ways I get mud to dry more quickly. On the counter* you see two box fans, and on the floor is a much stronger fan. On the counter is also a space heater. Hot air in the room absorbs moisture, sucking it out of the wet smoothing compound. I let the room heat up, and then I have to open the door and let the moist air out – over and over again.

The yellow objet on the floor is a heat gun. A heat gun acts like a hair dryer on steroids, and can get small stubborn areas to dry pretty quickly.

A few other things help speed drying … Walls coated with flat paint will dry more quickly than with glossy paint. And having the air conditioning and / or heat cranking away will help, because, while regulating the temperature, these climate-control systems also pull humidity out of the air. I also like to turn the HVAC system’s fan from “Auto” to “On,” so that air is circulating continuously, which also pulls humidity out of the air and helps the walls to dry.

*I normally keep a dropcloth on the vanity counter. But the vibrating fans can cause the dropcloths to slip, and you don’t want anything crashing down on the homeowner’s countertop. I do have lengths of self-grip shelf liner that help keep the fans from moving around too much.

Wall Prep – Missing Chair Rail and Stain Repair

March 31, 2019


What an unexpected surprise I got when I arrived at work to discover that the chair rail in this entry had been removed (top photo). Not only did I need to figure how to get enough paper to cover the additional wallspace, but I needed to smooth over the damaged wall area where the molding had been torn off. (See previous post)
I skim-floated the wall and sanded smooth. It looked great. But brown coloring from the torn Sheetrock had worked its way through the smoothing compound (second photo). Torn drywall is not something that I would normally worry about bleeding through wallpaper (you are concerned mostly with things like grease, ink, water, tobacco, rust, and the like), but this stuff was 60 years old, so who knows what its properties and characteristics were back then? And besides, it had already worked its way through a layer of joint compound – in just one night! No sense in taking the chance that it might bleed through this nearly-white grasscloth natural fiber wallpaper.

The Gardz penetrating primer / sealer (not pictured) I planned to use on the wall would be fine to hang wallpaper on, but could not guarantee that that brown stain would not work its way through the primer and through the wallpaper.

I applied the Gardz, because it’s a great penetrating substance that seals new smoothing compound, and also provides a good surface for hanging wallpaper on. Once that was dry, I followed that with a coat of KILZ Original, an excellent oil-base stain-blocker. But wallpaper paste will not stick to the new KILZ formula (required in order to comply with current EPA requirements.

A little 3″ width around the lower center of the room with wallpaper not sticking tightly to it probably would not be problematic. But you never know, and I didn’t want a “hula hoop” of delaminated wallpaper circling the room. So once the KILZ was dry, I followed up with a coat of a wallpaper-specific primer, Romans Ultra Prime Pro 977.

Now the room is ready for wallpaper, without fear of a band of tan bleeding through the new surface.

Contractor Patches On Top Of Wallpaper – Bad Idea

February 19, 2019


This home experienced a water leak, and the bottom 2′ of drywall had to be cut out and replaced. When taping-and-floating in the new drywall, the contractor didn’t bother to remove the existing wallpaper, but put his smoothing compound right over it. This is bad enough if the old paper is paper, but this wallpaper is vinyl – something you really don’t want buried under layers of joint compound and new wallpaper.

Vinyl is shiny, and few materials will stick well to it over a period of time. It is also thick, and that increases the likelihood that seams will pop up, even if they are buried under this “mud,” as we call it.

So I took a razor and cut above the contractor’s patch. Then I stripped off all the wallpaper above the patch. This left a difference in height between the patched area and the newly-stripped area, which would create a visible ridge under the new wallpaper. So then I took my own smoothing compound (joint compound) and floated over his patch and the now-bare wall, to eliminate any uneven areas.

Waited for it to dry, sanded smooth, removed dust, primed with Gardz, and finally was able to hang the new wallpaper.

This took a LOT more time than I originally planned for this job, but it was worth it to keep vinyl wallpaper from being underneath the new paper, and to prevent any bumps or irregularities from showing under the new paper.

Wall Sealing Whoops

September 26, 2018


Today I prepped a room where the drywall had been badly torn when the old wallpaper was stripped off. This happened because the original installer hung the wallpaper directly on the drywall, with no coat of paint or primer to protect the drywall.

Before I could smooth the wall surface, I had to seal the torn drywall, because moisture on the torn areas would cause the brown paper to bubble. I rolled on a heavy coat of Gardz, a water-thin, penetrating product that is designed to soak into the porous material, bind everything together, and dry hard. It is supposed to dry inpenetrable by water.

Once it was dry, I skimmed over it with joint compound (which will be sanded smooth later).

As you can see, the Gardz failed to do as claimed, and it allowed moisture from my smoothing compound to seep through it and enter the torn paper of the drywall, which then expanded and bubbled. I’ve got a big mess on my hands!

Tomorrow, when everything is dry, I will sand smooth. Usually bubbles like this dry out and then sand flat. But the large loose areas have me a little worried. They may still be loose and bubbled, and they may swell again when the wall is given its final coat of Gardz.

I may end up having to cut out some loose areas, refloat, and reprime.

Not good, because this could add a full day to this job, and because there could potentially still be unstable areas under the surface. Never good to have an unsecure surface under your wallpaper.

Getting Smoothing Compound to Dry

September 11, 2018


Textured walls have to be smoothed before the new wallpaper can go up.

Getting smoothing compound (drywall joint compound) to dry takes – dry air, moving air, air-conditioned air, heat …. and a lot of time. Today’s job had particularly thick textured walls, which would take a long time to dry.

So I hastened things up with a few accessories. Here you see one box fan on the floor aimed at a wall, another box fan on the ladder aimed higher on a wall, a very strong black floor fan shooting dry air into the room, and a space heater under the sink cranked to “high.”

When I shut the door, the warmth from the space heater collects in the air, and pulls moisture out of the smoothing compound. Then I will open the door and let the floor fan pull dry air-conditioned air from the hallway into the room, pushing the hot, humid air out.

Done enough times over a long period of time, you can get smoothing compound to dry more quickly than it would on its own.

Contractors and Painters Should NOT Prep Walls for Wallpaper

July 14, 2018


This home in the Meyerland neighborhood of Houston was flooded during Hurricane Harvey, and has been redone, and is now ready for final touches, like decorating, i.e. – wallpaper!

The first three photos show how the contractor left the walls. It’s hard to conceive how anyone could think these walls are “ready for wallpaper.”

What you are looking at is where the contractor ripped off the top, inked layer of the original wallpaper. Most of them don’t realize that there is a backing layer of paper that is left on the wall, that should be removed, too. Simply soaking this with a wet sponge will reactivate the paste and allow the paper to be removed easily, and with no damage to the wall (esp. if there is a good primer underneath the paper). Read my page to the right “How to Strip Wallpaper” to see how this should be done.

Instead, this contractor left the paper backing on the wall. Some of this porous backing is exposed. Other areas have been covered with the paint that was used on the woodwork. This solvent-based paint “raises the grain” of the surface it’s applied to – see all the hairy fibers from the wallpaper backing that have gotten stuck in the paint and raised up? Some of them are more than 1/4″ high. They create a gritty feeling on the surface, like really coarse sandpaper.

The surface is uneven, and the bumps will show under the new paper. The unevenness also means that areas of the paper will not be able to contact the wall, so there will be gaps and air bubbles and poor adhesion. The backing of the original wallpaper has been exposed, and when new, wet, pasted wallpaper gets placed on top of that thirsty paper backing, it will absorb moisture, expand, and bubble.

I had three missions. 1.) Seal the surface 2.) Smooth the surface 3.) Prime with a wallpaper-appropriate primer.

I rolled on a coat of the penetrating sealer Gardz to seal the surface, so that my following treatments would not cause the paper backing to bubble. When that was dry, I skim-floated the wall with a coat of joint compound. In the areas where the hairs were 1/4″ high, the skim coat was pretty thick, and took a good while to dry. Once that was dry, I sanded it smooth, then vacuumed the dust of off the floor, used a damp sponge to wipe residual dust off the walls, and then followed up with another coat of Gardz. It will soak into the joint compound and dry hard, forming a stable surface for the new paper to adhere to.

The last photo shows the wall once I finished.

If You Want Smooth Walls, You’ve Gotta Put Up With a Little Dust

July 7, 2018


The walls in this house had a pretty heavy texture, which I wanted to smooth before hanging their wallpaper. This involves skim floating the walls with joint compound (commonly referred to as mud). Do a search on those terms here to learn more about this process.

Once the mud is dry, I sand it smooth. This makes a dust – and the thicker the wall texture, the more the dust. Here you see what has accumulated on the floor after sanding.

Don’t worry – I bring in my Shop Vac and clean all the dust up.