How to Skim Coat Your Walls Before Painting?

If you have dabbled in painting or construction, you may have heard something called finished levels.

Essentially a finish level is how well finished a piece of drywall is on a scale from 0 to 5.

Zero tends to be completely unfinished, with no tapering and especially no skim coat, while a five is a perfectly skimmed and finished wall that you can shine a bright light on and would not be able to tell where the wall ends or begins.

When it’s about skimming the walls before painting, there are dozens of different ways. Depending on who you ask there is a wrong way and a correct way.

IMO, either way, is correct if it brings you to the final product, a perfectly smooth wall.

In this article, I will be describing my personal favorite way to skim coat.

But before we come to our main questions of what, when, and how to skim coat, let’s try to understand more about the drywall finish levels.

What are the Levels of Drywall Finish?

Finished levels are an industry standard set by the major drywall companies and are commonly used in this profession.

Contractors use the purpose of the wall to determine how much finishing is required.

For example, the guidelines only suggest using levels 0, 1, and 2 for areas that are generally out of view of the public such as an attic or a garage. These levels have minimum tapering and especially no paint.

While you increase the scale on the level (levels 3, 4, and 5), the wall generally looks better and better.

Generally, level three has some tapering and to hide the seam, a wall texture is used. This makes the wall appear much flatter; however, it will have a bumpy finish.

A level four wall will appear almost completely flat after it is painted with a minimum texture. It makes sense that a level four is better than a level three.

So, what about a level five?

A level five wall is the best of the best, where a skim coat is used on the entire wall to make it appear flat. This high level of the wall should look completely flat and will not have any imperfections, even in an inspection under hard light.

The only way to get this best of the best level on your wall is to skim coat, as it completely removes all imperfections and hides the joints of the drywall perfectly.

What is Skim Coating?

Long story short, a skim coat is a small coat of drywall mud on top of a piece of drywall that helps it become flatter.

When you build with drywall or have an existing drywall in a home environment, it can lose its flatness over time, particularly at the joints.

And who would want a bumpy wall?

A skim coat is able to fix all these problems, relatively quickly which is why painters and contractors have agreed to make a textured wall look smooth in bright light through skimming.

In fact, the skim coat is the only way to meet the drywall level finish of five, which is the best of the finishes generally used on walls with bright lights.

When to do the skimming?

We mentioned it earlier, but not every wall has to be skim-coated. In fact, not every wall should be, as the skim coating is very time-consuming, and can be tricky if you are doing it yourself.

Skim coats should only be used on walls that will be heavily looked at and have a lot of light on them. This means rooms with any skylights or hallways with lots of light sources should probably have level five finishes applied to them.

Typically, if you want to smooth out your wall (and hide imperfections) without plastering; sanding and skim-coating the walls is a way to go. Or you can have a skim coat done in any room you want to look particularly perfect, such as a living room where you will host a lot of guests.

You can do it all through your house, but keep in mind, as it is a time-consuming process, it will increase your cost by a good amount, and some walls simply do not need it.

If you are working with a contractor, ask about skim coating and see what they recommend. But, if you are working by yourself, consider only using a skim coat on the most important walls.

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How to Skim Coat Walls Before Painting?

Skim coating can be a difficult task for even the masters of the trade. However, you will only get better if you practice; and to practice, you have to do it.

Items Required

The bread and butter of the skim coating require a 14-inch squeegee knife, a regular old paint roller, and of course, some drywall mud/compound to actually apply the skim coat and hide the imperfections in the wall.

To have the best outcome possible, here is the list of some additional items you will need for this project. You can pick up these all at your local paint store, or if you look, maybe even online, at stores such as Sherwin Williams or Amazon.

• A Mud Pan – to hold the mud you are currently using
• A paintbrush – to apply the mud to the walls quickly
• A taping knife – to smooth out the coat of mud
• Masking tape and primer – for preparing the walls
• Sanding tools such as 120 grit sandpaper, a sanding block, a sanding pole, and safety glasses – to smooth the wall at the end

Just a quick note, the use of a squeegee knife and taping knives are heavily debated within this community, however, I stand behind the squeegee knife as a good alternative between knives as it is simply easier to use. You can personally choose which one you prefer, but I recommend having both on hand.

Also, the roller sleeve that is used with the paint roller should match the size of the roller and should be the smoothest one you can find.

The Steps You Need to Follow

Skim coating is a lot easier said than done. This means the steps are relatively straightforward but can be hard to get perfectly correct.

However, if you follow the steps, you will be able to skim-coat well, at least a little bit of a wall. So let’s just get into it.

Step 1: Prepare the wall

Before you start to skim the coat, you will have to do some basic preparation of the wall.

First, you should add masking tape to the bottom and top of the wall and any other place you wish to mask off.

We will be applying primer and drywall mud to this area so if there is anything you don’t wish to damage, remove it, or mask it off.

After this, you can fill the holes (if any) and add primer to the wall if the wall is not primed. A primer like Zinsser Drywall Primer or BM 253 primer (Benjamin Moore) will help your compound stick and seal the wall better. So, you can use them fairly well for skim-coated walls.

Step 2: Add mud

Here you need to use a paint roller to apply the mud to the wall. The mud shouldn’t be too thick or too thin.

A good standard is that the mud should be applied to the wall and just barely not roll down it. Go light on the mud and try to make it as smooth as you can – this is called a skim coat, not a heavy coat.

Step 3: Smooth the mud

This is the hardest part of the project since you have to be perfect in an imprecise task.

You will want to get your knives out and flatten the mud. Starting in a corner, pull down through the mud, removing in excess. You will have to go up and down and side to side.

This is a difficult task, but don’t get frustrated. You may get through perfectly by looking up some YouTube videos to learn the technique and the fastest ways.

Step 4: Repeat and sand

You will want to repeat step 3 a few more times for a total of two or three coats. This may sound like a lot, but this will ensure you get the smoothest plastered walls possible.

Also, since the coats dry relatively fast, you can complete this project relatively fast.

After you have all of the coats applied, you will want to go in sandpaper and sand down any of the peaks, and just smooth it out.

You can use a sanding block for most walls, but I recommend using a manual sanding pole to help you reach up to heights wherever needed to make the process easier.

Step 5: Finish with the paint

On average, it takes around 3 days for the skimmed surface to dry and be ready to apply the paint. So, make sure if you need to paint, give it proper time to dry.

Drywall companies also suggest that a skim coat should be accompanied by gloss or semi-gloss paint, as other reflective paints will show the mistakes in the skim coat.

In a similar way, they suggest you do not use paints with textures such as eggshell or knockdown, as that kind of defeats the whole purpose of the flatness of a skim coat.

The cost to plaster, skim coat, and paint the walls will generally depend on the job size, condition of the walls, and finish options you choose.

Just in case you find all this troublesome, there is a better alternative to skim-coating walls and that is wallpaper or wall liners.

Mist coating is another good alternative to skim coat in which a thin coating is applied on a plastered wall as a substitute. You can put them up and stay relaxed for a year or two!

Difference between Skimming and Plastering

While plastering and skimming may seem to be similar for many, it’s not the same. So, before you try any of these processes, it’s important to know the difference between both.

Skimming is a process where a thin layer of mud coat is applied to the plastered wall to achieve a smoother finish. On the other hand, plastering is a broader term that includes skimming as one of the whole processes.

Plastering services can be classified into 3 types. These include:

1. Lime plaster: Traditional plastering done using sand, lime, and water
2. Cement plaster: This is done on the masonry work using cement, sand, and water
3. Gypsum plaster: Thick plaster coat done on walls with calcium sulfate and water

In simple terms, you can say that skimming is a part of the process of plastering the walls to get a smooth finish. While you can skim-coat the walls without plastering, the process of plastering the walls isn’t said to be complete without skimming.

Furthermore, while a backing plaster will take around 4-6 days to dry, a skim coat should take relatively less time (around 3 days) to dry completely.

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Skim Coating vs. New Drywall: What’s the Better Option?

If your walls and ceiling are looking shabby, getting new drywall is not the only option. Depending on the condition of the current drywall, you can improve the way it looks through the skim coating.

Sometimes called level-five drywall finish, a skim coat fills in the dings, dents, and other rough areas of the existing drywall so you have a new surface that can be re-textured or painted.

It takes two layers of skim coating to do the job and there are good reasons why you should consider this alternative to putting up new drywall. Some of them include:

1- New Installations

If you have new drywall added to your home or office, then adding a thin layer of skim coating is recommended. Just a single layer can ensure that the surface is primed and ready for painting.

Adding skim coating is important because drywall may absorb the paint you apply differently compared to the joint compound and that will leave an impression for the best look.

2- Repairs and Fix the Damage

If the drywall has been repaired either on the wall or ceiling, it’s going to stand out from the existing drywall. By applying the skim coating, you can even out the surface so it can be re-painted or re-textured.

Additionally, if you are planning to remove the wallpaper before painting, removing old wallpaper can damage the surface of the drywall. Sometimes removing the outer layer of drywall paper may also expose the brown paper that is underneath.

At this point, the brown paper will need to have a prime surface sealer applied before you can add a skim coating. Otherwise, you will not be able to cover the damage.

3- Restore Old Ugly Surfaces

If your walls or ceilings look old, tired, and dingy, you can improve their appearance by adding a new skim coating. This will create a new layer that is bright and will take years off the appearance of your walls or ceiling.

Sometimes the problem isn’t that the surface of the drywall or painted wood paneling is old, it’s just unappealing. Outdated textures, colors, or patterns can make the surface quite ugly.

A new layer of freshly skimmed coat will provide a method of adding new textures, colors, or patterns that better suit your style. Plus, you do not have to rip out the old drywall to get the job done.

Can You Skim Coat Over Existing Paint – The Pros and Cons

Skim coating is an effective way to refresh your old walls without undergoing a complete repaint. And yes, you can skim coat even over your old paint, provided you are ready to do the required surface preparation.

This essentially means, before you start, check the condition of the existing paint—look for peeling or chipping areas that need attention. Use a putty knife to remove any loose paint and ensure a smooth base. Then applying a thin, even layer is crucial, as thick coats may lead to cracking.

While skim coating offers benefits such as creating a smooth finish, hiding imperfections, and being applicable over painted surfaces; it also has certain drawbacks which include the requirement of multiple thin coats which can be time-consuming. It’s also not ideal for high-moisture areas.

Types of paint that can be skim-coated

Keep in mind that not all paints are suitable for skim coating. You generally require the right type to ensure a strong bond between the new layer and the existing surface.

Flat paint is ideal because it lacks sheen, allowing better adhesion. Eggshell finishes can also be skim-coated with proper surface preparation, while satin finishes require sanding to enhance adhesion.

However, glossy paints are often too slick and demand extensive preparation before skim coating. Regardless of the paint type, always ensure the surface is clean and stable before beginning your project for the best results.

The Bottom Line

Skim coating is less expensive and far less time-consuming compared to adding new drywall.

So, if you are remodeling your home, need to repair the damage, or just want to brighten up the look of your walls or ceiling, a couple of layers of skim coating may do the trick which you can do yourself.

After a skim coat, the next step is to paint the wall and you should be essentially there. And by the time you finish, you will have a lot more appreciation for local contractors that provide these skim coating services.