Can You Undercoat Woodwork with Emulsion?

Today, it’s easier than ever to take on do-it-yourself projects like priming and painting, along with other projects without being an expert on the subject. Woodworking is no exception, but since woodworking entails so much, it’s important to have the right answers to any questions being asked – especially when it comes to priming and painting.

Woodwork is often painted or coated to create a desired look or appearance. This has left many DIY’ers and woodworkers asking: can you undercoat woodwork with emulsion? You can undercoat woodwork with emulsion, but it doesn’t mean you should. When it comes to woodwork, emulsion should really only be used for its original intended purposes. However, the emulsion can be used to undercoat small areas of the woodwork if absolutely necessary.

There are a few reasons why it’s best to avoid undercoating woodwork with emulsion, and there are some other things you should know too – like what emulsion is and what it’s used for, why it’s important to undercoat woodwork, what woodwork should actually be undercoated with, and how to properly use emulsion on woodwork.

Below, you’ll have all the information you need to use emulsion on woodwork in the proper ways and ensure you get the best results possible from your woodworking projects.

A Look at Emulsion and Undercoating Woodwork

To understand why you should probably stray away from undercoating your woodwork with emulsion, it’ll help you to know what emulsion actually is, what it’s used for, and other important facts like why woodwork should be undercoated and what you should actually undercoat woodwork with.

Let’s take a look at the basics of emulsion and undercoating woodwork.

What is Emulsion?

The emulsion is a water-based paint, and is used primarily for painting interior walls, although it can be used for exterior surfaces as well. The emulsion is thick, and often isn’t ready to use right out of the container; it needs to be thinned with water before use. Although it requires some prep work before using, it’s generally easy to use and apply.

Emulsion dries more quickly than oil-based paints and other water-based paints and can be applied in a variety of ways, like rolling, brushing, spraying, and dipping. Emulsion paints are ideal for use on ceilings and interior walls because they’re more resistant to humidity and mildew, meaning they can even be used in the steaminess of bathrooms and kitchens.

Emulsion holds fairly well to most surfaces, and it’s possible it may hold to woodwork if applied to it as an undercoat. However, once again: just because you can use emulsion as an undercoat on woodwork doesn’t mean you should.

Why You Should Avoid Using Emulsion as an Undercoat on Woodwork

As mentioned previously, the emulsion is a paint that’s ideal for interior and exterior walls and ceilings. That’s great, but the interior and exterior walls and ceilings typically aren’t just made of the woodwork.

The properties and uses of emulsion are some of the driving factors as to why emulsion just isn’t a great product to use as an undercoat on woodwork. That being said, there are several reasons why it would be best to avoid using emulsion as an undercoat on woodwork:

  • It’s unlikely emulsion will stick to the wood surface.
  • The emulsion is thick; it’s hard to get even brush strokes and an even, smooth finish.
  • Since emulsion is so thick, it’s hard or near impossible to sand down, further deterring from a smooth finish.
  • The emulsion is generally used after a primer has been applied, or after a coat of paint has already been applied – not directly to wood surfaces.
  • The emulsion is water based, so if you plan on using a gloss or finish on the woodwork that’s oil-based, the two likely won’t mix well.
  • Using emulsion as an undercoat on woodwork makes it more likely that the finished product may not turn out as intended.

Why to Undercoat Woodwork

You may be wondering why you should go through all the trouble of undercoating your woodwork before painting it in the first place. You wouldn’t be the only one! As it turns out, undercoating woodwork is pretty important.

Primer vs. Undercoat

First, let’s distinguish between primer and undercoat. Primer is used to seal and protect the bare surface of the woodwork, and the undercoat is used to create an even surface on the woodwork before painting or finishing.

Primer’s binding agent is more adhesive than the binding agent in paint, so it sticks to the woodwork better than paint or emulsion would. Additionally, paint or emulsion sticks to primer better than it would to the bare wood surface.

In addition to creating an even surface, undercoating woodwork can also help provide protection to the woodwork and block intense or underlying colors from shining through to the top coat.

Undercoating (With the Right Products) is Important

So, as you can probably tell after learning the differences between primer and undercoat, undercoating is important. But it’s even more important to undercoat woodwork with the right materials – an undercoat intended for woodwork!

Using a primer and then an undercoat rather than just using emulsion will bind better to the woodwork, lead to a more smooth surface, and lead to better protection of the woodwork.

To undercoat your woodwork, you can purchase a wood primer and then a wood undercoat and apply them, or you can buy a primer and undercoating solution in one (that way, you only have to apply one product). However, if the woodwork you plan on undercoating is going to be outdoors, it’s better to prime and undercoat the woodwork separately.

How to Properly Use Emulsion on Woodwork

Okay, so now you know you probably shouldn’t be using emulsion as an undercoat on woodwork – and for some good reasons. So how do you properly use emulsion on woodwork? Using emulsion on woodwork isn’t extremely common, but it can still be done.

The emulsion is used on woodwork after priming and undercoating have been done to the woodwork. Often, those who are painting woodwork use oil-based or water-based gloss or eggshell paints. However, if the gloss or eggshell isn’t your desired look for your woodwork, you can turn to emulsion paint.

Step by Step: Using Emulsion on Woodwork

Using emulsion on woodwork can be relatively easy if done correctly. These are the steps to follow when you have decided to use emulsion paint on your woodwork instead of gloss or eggshell paint:

Before: Gather Your Materials

Before you can get started on the process of using emulsion on your woodwork. You’ll need to gather some materials. At the very least, you’ll need:

  • Your chosen woodwork piece
  • A designated work area
  • 80-100 grit sandpaper
  • 200-220 grit sandpaper
  • Rollers, brushes, or desired tools for painting and applying primer, undercoat and emulsion
  • A shop vac or rag to remove sanding particles and dust
  • Woodwork primer
  • Woodwork undercoating
  • Your desired color of emulsion

Step One: Sanding

If your woodwork has any old paint, or if it has any blemishes or uneven surfaces, get a hold of some 80 or 1000 grit sandpaper and start sanding! Once the main portion of the old color(s) have been removed, you can switch to higher grit sandpaper to smoothen the surface even more.

Step Two: Priming

Time to get out that primer we’ve been talking about! Make sure your woodwork doesn’t have any leftover dust or particles from sanding and then apply your primer. Apply several thin layers of primer to ensure it binds and results in an even surface.

Step Three: Undercoating

Next, you’ll need to get the undercoat we’ve also been talking about. Apply your undercoat as instructed by the manufacturer and wait for it to dry.

Step Four: Emulsion Time

Since you’ve decided to use emulsion rather than a gloss or eggshell paint, you’re ready to get your emulsion paint out and start to work on painting your woodwork. Apply two or three coats of your desired emulsion paint to the woodwork, then allow it to dry thoroughly for two to three days.


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