Can You Use Polyurethane Over Chalk Paint? (How-To)

If you are looking to bring a lustrous finish to your chalk-painted furniture, Polyurethane is one of the best ways to safeguard and beautify those ragged tables and bookshelves while preserving their vintage look.

Yes, polyurethane is used as a sealant over the chalk-painted pieces to brighten their matte-finished dull look.

A paintbrush or a spray is often used to coat the surfaces, which, if kept bare, will decay with time. Polyurethane gives the best watertight protection, making your chalky surfaces remain untouched by rain or moisture.

On top of giving much-needed coverage to chalk paint, it is affordable and highly recommended by experts. Polyurethane shields the surfaces from fungus, rain, dirt, and change of colour.

Polyurethane is made of natural molecules, so it does not emit harmful chemicals, unlike other varnishes.

A Polyurethane coat adds to the life-cycle of whatever it is put on.  It carves out the natural aesthetics of the objects without hampering the original look.

If you want durability and a polished look to your property, Polyurethane is one of the best varnishes out there.

What Kind of Polyurethane Do You Use On Chalk Paint?

There are essentially two types of Polyurethane topcoats used on chalk paint that are discussed below

Oil-Based Polyurethane

These were the most preferred coats for chalk paints because of their durability. However, oil-based products are musty and take more than 24 hours to dry. They are most likely to turn yellow over time and make the white-painted pieces stained.

The process of applying the oil-based Polyurethane is tedious and requires brushes to be cleaned with mineral spirits.

This sealant is water-resistant but may cause an unusual crack when exposed to sunlight. With the growing competition in the market, the water-based coats have given the old ones the run for their money.

Water-based Polyurethane:- 

Water-based coats have comparatively less odor and are easier to wash with warm water. It takes about 6-12 hours for the water-based Polyurethane to dry off, and they don’t become pale as with the usage of oil-based Polyurethane.

The criteria to look for the best Polyurethane coats are given below:

  • – Clarity
  • – Water Permeability
  • – Affordability
  • – Durability
  • – Smoothness
  • – Ease of Application
  • – Stain Resistance
  • –  Washability

How Long Should Chalk Paint Dry Before Applying Polyurethane?

Chalk paint should generally take anywhere between 30-60 minutes to dry. However, waiting for over a day before applying polyurethane gives a better finish to the surface. It is necessary for the chalk paint to fully leave its effects before coating it. 

The paint might feel dry to the touch, except that the solvents need to evaporate and reach their maximum hardness for the chalk paint to cure completely.

To see if your chalk-painted surface is ready to be coated, press your fingernail against it and look for the clear marker of a visible indent. If it doesn’t leave any trace, you can begin applying Polyurethane.

Factors that affect the paint cure are-


At lower temperatures, the paints condense and take longer to dry. If it’s too cold, the paint’s life expectancy reduces and starts dripping, creating uneven surfaces.

Wood Type

Some wooden furniture impedes the drying time because of the chemicals produced by them. Rosewood and Cedar Wood should be avoided to rid of the time-consuming process that it takes to cure.


A better access to fresh air makes it easy for the paint to dry, which is why windows and doors are usually kept open.


Being highly porous, wood absorbs moisture and eventually makes the paint peel off or create bubbles.

The factors mentioned above determine how long you should wait before applying Polyurethane on Chalk Paint. You must attend to all the details before deciding to coat the painted surfaces. Sometimes, a minor mishap wastes all the time and effort put into decorating a piece of art.

How To Apply Polyurethane Over Chalk Paint?

Polyurethane is specially formulated to bond with another paint when it dries. There’s always a proper way to do things, and it isn’t any different when applying Polyurethane over Chalk Paint.

To get a smooth protective coat on a chalk painted surface, you are required to follow these important steps to ensure a barrier to your paint.

1. Clean The Surface

 You must steer clear of any grease stains or dirt when putting on Polyurethane. Washing off the surface with a detergent that cleans the surface thoroughly is imperative to a fine coating. Painters often mix trisodium phosphate and warm water to increase adhesion.

Related Read: Will Polyurethane Stick to Tacky Stain?

2. Sand Down The Surface

After cleaning the dust off and letting it dry, choose 80-120 grit sandpaper to smoothen the surface and get rid of the scuffs.

When the surface is adequately scratched, wipe away the residual material with a wet cloth. This leaves a well-defined surface ready to be coated. Rubbing the sandpaper against the wooden piece makes it all set for the next step.

Related Read: Should You Sand Polyurethane Paint?

3. Apply The Polyurethane

It is the step where you must find the most suitable form of Polyurethane to apply. It will help if you avoid using a roller since it leaves out bubbles behind.

Brushing is the best and one of the oldest ways to build a coating film. However, for the surfaces which are hard to reach, spraying on is the only way to cover those edged sides that a brush can’t fill in.

You can wipe the contoured surfaces that prevent the Polyurethane from running. However, a thinner coat is always a concern at places where there is more exposure to abrasion.

Related Read: Can I Apply Polyurethane on Plastic?

4. Wait To Dry & Apply a Second Coat

After the first successful application, wait out until it completely dries, as will be mentioned on the container.

You can then use the same sandpaper to remove the dust and flatten out the bubbles. Any inconsistencies left on the surface will be further resolved with scuffing.

The scrubbed surface is now ready for a second application. This is to make sure of an even distribution of Polyurethane in making the coat even more durable.

You are now looking at the refurbished furniture that’s all-new with the gloss. Painters have their own way of doing their artistic coating; however, these are some of the essential steps to getting a clear coating, free from any deviation.

Related Read: Can You Apply Polyurethane Over Old Polyurethane?

Can You Use Polyurethane Over Chalk Paint instead of Wax?

Yes, in fact, Polyurethane is a more sought after option than using a Wax on Chalk paint. Here we will discuss the various benefits of using this varnish over wax.

The core problem with using wax is that it doesn’t seem to get any easier. There’s often a need for repainting the surface when it somehow gets sullied.

You may wonder why it is prone to get the stamps from cups, making drops of water leave marks. It is because moisture and wax don’t go hand in hand.

A slight variation in how you apply the wax on the Chalk paint makes a dramatic difference. Wax is a low durability finish and doesn’t stand strong for frequent use. You also need to remove all the wax before trying to repaint.

On the other hand, Polyurethane gives a hard finish and protects against dirty stains. Once the surface is cured, any cleaning agent could be used for washing.

For a waxed piece, you must be careful about how you clean it. One of the major cons of waxing a Chalk painted surface is that you might need to reapply the wax every few years down the road.

These reasons clearly state and strengthen your choice for going for Polyurethane instead of wax.

Related Read: Can You Use a Roller To Apply Chalk Paint?

Can You Mix Polyurethane and Chalk Paint?

It isn’t advisable to mix Polyurethane and Chalk paint since the resultant will be chunky, it can only be combined with actual acrylic paint.

However, the Polyurethane varnish can be applied over the Chalk paint for protection from overuse and a glossy finish. These coatings may look similar to other forms; they have distinctive characters that make them ideal for putting on the Chalk paint.

Related Read: How To Mix Chalk Paint With Latex Paint?


The broad applicability of Polyurethane at different places is because of its various characteristics. The water-based Polyurethane coatings are non-flammable and are best suited for areas where combustion is likely to occur.

They have been used as anti-corrosion coatings and act as barriers to various environmental factors. The range of its application varies from floors, industrial equipment, roofs and Aircraft.

Most of all, it is best used as a glossy protective coating for chalk painted surfaces to retain the newness and durability of the material.

In addition to being of use to chalk painted pieces, it works well for all kinds of wooden furniture because Polyurethane is resistant to water and is resistant to moist air.

Polyurethane provides maximum protection to high traffic surfaces. It comes in different finishes such as satin, semi-gloss and high-gloss. It lasts a lot longer than any other coating in the market.

Leave a Comment