Skim coating involves putting a thin layer of joint compound over a wall surface to smooth out dents, dings, and other imperfections to produce an even finish. Skim coating can be applied on fresh plaster, drywall, or painted walls.
However, can I skim-coat over paint? Yes, but under certain circumstances. Before choosing to skim coat over your wall and paint, you should examine their state. You must first repair any cracks, damage, peeling paint, or thick layers of paint on the wall.
You must lightly sand the surface and clean off any dust or debris, whether the paint is gloss or semi-gloss. You should also apply a setting-type joint compound for greater adherence on painted surfaces. Applying Skim coating over the paint is an excellent option to update your walls and cover any imperfections.
In our guide, you can learn more about the whole process of skim-coating old or new drywall. By the end, you’ll see how to properly tackle old paint, fill minor cracks on uneven surfaces, and obtain an even surface on the whole wall. (Read Can You Paint Over Thompson’s Water Seal)
What Is Skim Coating?
A skim coat is a thin layer of drywall joint compound, the ones in the know call mud, which is used to give walls a glass-like gloss. Although you use joint drywall compound rather than plaster, it is also called plastering a wall. Skim coating aims to smooth down purposefully created wall texture and repair damaged walls.
Some walls have a coating known as orange peel or knock-down texture. Instead of textured walls, some homeowners may prefer smooth walls. Instead of scraping away the texture material, it can be easier to skim-coat walls for a more straightforward mess-free option.
Skimming walls has benefits and drawbacks, such as the amount of sanding dust. However, it is less expensive compared to changing drywall, removing texture, or installing paneling to plaster walls to get a smooth surface.
How To Prepare Wall for Skim Coating?
Your walls’ flaws and cracks are difficult to conceal with just paint. Hence, to say goodbye to lumps and bumps, you require the ultimate makeover for your walls. This convenience is only available by applying a thin coat of material, or what we know as skim coats. It will also welcome even and smooth surfaces as an option.
But, you don’t just jump in as it can be tricky, and you need some gear.
Here’s the first look at the skim coating process.
1. Grab Your Gear:
Here’s what you need to skim-coat walls.
- Quick-set joint.
- Ready-mixed joint compound.
- Water-based primer.
- Paint roller
- Skimmer plate
- Taping knife
- Drywall knife (optional)
- Safety glasses.
- Plastic sheets.
The room needs to be set up next. As walls are repaired, dust is created as usual. So, it would be wise to protect your floor from mud by removing your belongings. Alternatively, you might use plastic sheeting to cover the furniture. Furthermore, covering doorways to stop plaster dust from settling in the nearby rooms is a good idea.
3. Clean Walls
Ensure the walls are clean and crack-free before you start skimming. You may get a smooth finish with the fewest coats possible in this manner. Start by removing loose debris with a scraper before filling the cracks with a graded ready-mixed joint compound. Reduce the number of marks and wiping lines you create using a small drywall knife.
After repairing the damaged walls, dust and wipe them down to remove any dirt that might prevent adhering.
4. Prime Your Walls
It’s time to prime your walls now that they have been thoroughly prepared. You must use a water-based primer for optimal results, especially if you have painted plaster.
Take your roller and spread a coat of primer over the entire surface you plan to skim-coat. The purpose of the primer is to improve the better adhesion of your joint compound. Give the surface adequate time to dry as usual before adding anything additional.
5. Mix Your Plaster
Mixing your plaster comes next. If you’re working with a quick-set joint compound, mix it with water before applying it. Before it gets tricky, you can confirm the time restriction by checking the instructions. To simplify the process, take the big bucket and use a drill to mix your compound within. The compound should become mud-like in consistency during the process. (Read Can You Mix Water Mixable Oil Paint With Acrylic)
6. Apply Your First Skim Coat
The time has come to spread the first skim coat. Load your compound mix onto a skimmer plate. Make sure one hand holds the skimmer plate while the other continues to spread the mixture while applying the initial coat. Packing a small bit of plaster on your trowel is a good idea before adding more later. Then carefully and evenly glide it over the wall.
7. Apply Second Skim Coat
You don’t need to wait for the first coat to dry before applying another. For a smooth finish, keep dragging your trowel with a second one. If grooves are still visible after the second coat has dried, apply a third coat and remember to draw the trowel vertically.
8. Dry and Sand
Let the surface of the final layer of your skim coating dry for 24 hours after applying the third coat. Then, take some sandpaper and start to smooth away any visible flaws. With 180 to 220 medium-grit sandpaper, you should smooth off any rough edges or grooves.
How To Paint Skim Coat On Walls
Here’s a new technique for smoothing damaged walls that is simple to learn
Step 1: Prepping Walls
In this technique for retexturing a wall, you roll the entire wall with a stain-blocking sealer rather than merely spot-priming it. Use a drywall primer that dries quickly and seals off stains on the walls and any existing paint.
The primer seal’s loose paper encourages better bonding of the joint compound. They are thin layers that cannot level uneven portions or repair holes or torn-away paper. Use a setting-type joint compound to address these issues.
Before beginning the skim coating, let the compound harden. Before applying any joint compound, let the sealer completely dry before moving on to the next step.
Step 2: Roll On Your Mud
Mix all-purpose joint compound to a consistency similar to mud used for bedding tape or thin enough to roll on the wall. With a heavy-nap roller, apply a thin layer of all-purpose joint compound to the walls.
Work in small parts to smooth out the joint compound before it dries. Don’t worry if the first coat starts to break; mix the next coat a little thicker by spooning in some fresh mud from another bucket.
Roll mud on a four-foot square surface with a 1/2-inch. nap roller.
Step 3: Trowel Your First Coat
After every few strokes, wipe the blade with a damp rag and then use a mud pan to remove any extra mud that accumulates on the blade. Set the squeegee knife against the wall and drag it down to smooth the joint compound, beginning at the top corner. Until the segment is finished, make careful to overlap each pass. (Learn How Long Does It Take For Spray Paint To Dry)
Step 4: Pull from the Bottom Up
You might need to review some areas a second time. It won’t take long to get the hang of using the squeegee knife. After finishing the top piece, smooth the joint compound on the lower half and roll it by drawing the trowel upward.
From the bottom up, drag your squeegee knife.
Step 5: Scrape Off Lumps
Let the first coat of joint compound dry. If the air is humid, you might use a box fan or a space heater to speed up the drying time. Remove lumps or proud mud lines with a 5- or 6-in. putty knife between coats to prevent streaks in the subsequent coat.
You can apply the second coat after brushing the wall clean.
Step 6: Change Direction On Your Second Coat
Applying two or three coats of a joint compound may sound like a lot of work, but the taping knife makes the process rapid, and the thin layers dry quickly. At a right angle to the preceding layer, trowel off each new layer.
Apply a third coat using a trowel if any blemishes or defects are still visible after the second coat dries. Pole-sand the wall with 120-grit paper once the last coat has dried. Use 100-grit if it isn’t smooth.
Skim Coat Application Methods
When covering painted plaster, or new drywall, you have options for applying your skim coats:
1. Paint Roller
A popular way to apply drywall compound is to roll it onto the surface with a paint roller cover and frame. The drywall compound applies rapidly and is simple to remove.
2. Drywall Knife
The drywall knife, which is always used to smooth down the drywall surface for skim coating, can also be used in earlier steps to apply the coating to the surface. This offers the benefit of reducing tool purchases. The application is tedious and slow.
3. Texture Sprayer
The quickest and easiest way to apply drywall compound to the wall is with a sprayer.
You cannot use a regular paint sprayer; you must rent a texture sprayer. After spraying on drywall compound, it is finished like roller or knife drywall compound.
For a smooth result, preparation for skim coating is crucial. That means you must prep the wall before skim coating. Priming seals loose drywall paper. Apply one to two thin coats of appropriate primer to the wall and wait until it is completely dry before you begin skimming.
What You Need
- 12-inch drywall knife
- Drywall mud pan
- 9-inch paint roller
- Fine-grit drywall sanding screen
- 5-gallon bucket and paint rolling screen
- All-purpose drywall compound
- Clean water
- Painter’s tape
1. Prep the Work Area
Cover non-skim-coated regions. Light switches and outlets should have their electrical connections turned off. Remove the faceplates, then cover the outlets or light switches using painter’s tape. Drop cloths should be spread out and taped to the wall baseboard.
2. Mix Drywall Compound
Use light-body drywall compound rather than the heavy body, as this doesn’t serve any purpose. Plus, light mud is easy to sand smooth. Mix the drywall compound according to the product ratio on the drywall compound instructions. Shorten the water to make a heavier, stickier product. The skim coat becomes stronger as a result and is easier to apply. Mix until a firm yogurt-like consistency.
3. Roll Drywall Compound
A section 8 feet high and 2 feet wide should be rolled out. To force bubbles out, press the roller against the wall. Working time is influenced by the amount of drywall compound used, ambient temperature, and airflow. To prevent drywall compounds from drying out, keep working zones small.
Maintain a consistent drywall compound surface. The process will be simpler if you apply drywall compound consistently, even though it is scraped off.
4. Skim First Section
Using the 12-inch knife, remove the drywall compound. Scrape in columns, putting light pressure on the left side of the blade. This removes defects on the left side but leaves a low hump on the right side. (Read Can You Paint Over Lacquer)
5. Skim the Remaining Sections
Make a second pass next to the first line. Once more, apply pressure to the left. This removes the left ridge. Overlapping guarantees that the drywall knife covers the majority of the ridges. Less drywall sanding is required later.
6. Sand Dried Skim Coat
Let the skim coat dry. It should be dry within an hour or two, and using fine-grit drywall sandpaper, finish with a light sanding.
Wall Skim Coat Troubleshooting
It’s hard to see drywall compound on the wall
Set up a work light on the floor to project a low-angled beam onto the skim coat surface. This aids in locating high and low points.
Drywall compound won’t stick to the walls
It’s possible to mix the compound too thinly. To firm the product, add more dry ingredients and mix once more. The drywall compound may not adhere well to walls painted in high gloss paint. Before applying the skim coating, these walls should be lightly sanded.
How thick is a skim coat?
A skim coat is between 10 and 12 mm thick.
How long before you can sand a skim coat?
Any skim coat surface should wait 24 hours before sanding. Sanding before this time will cause the skim coat to peel off, requiring a new start.
Do you need to sand after skim coat?
Sanding after a skim coat is crucial since it helps to smooth out the spots you didn’t perfect with a trowel. Sanding before the skim coat dries is not necessary.
How smooth does a skim coat need to be?
A skim coat should be smooth, like pancake batter. Ideally, use a broad knife at a 10-degree angle to the wall to make it smoother.
Is it worth it to skim-coat walls?
If you want a damaged wall to seem smooth and seamless, skim coating is definitely worth the time and work.
Skim coating walls can be used to repair issues left over following wallpaper removal in addition to certain damage on drywall. Living areas, such as dining rooms, are frequently skim coated.
Can I paint after skim-coating a wall?
After skim-coating a wall, you should paint it. If left incomplete, the skim coating, which is delicate, can be easily harmed. The skimmed wall will be protected by primer and paint. Wait until the skim coating is completely dry before continuing.
Can you skim-coat an entire wall?
Skim-coating a complete wall or a room can change it, even though it can be time-consuming.