How to Seal Chalk Paint for Outdoor Use

How to Seal Chalk Paint for Outdoor Use? (Full Guide)

In Exterior Paint, Tips by Jamie

Chalk paint is excellent because it doesn’t require any prep. You can just paint right over the top of any old paint and it looks great. That’s why it’s such a popular choice for furniture. But can it be used outdoors? Yes, but you need to seal it to protect it against the elements.

The best way to seal chalk paint is to use a clear coat like spar urethane. Once the paint is fully dried, you can apply this sealer over the top to protect against moisture and UV damage. Apply 4-6 coats, sanding lightly between each one for best results. 

If you plan to use chalk paint outdoors, read this article first. It will give you a full guide to sealer chalk paint and show you some of the best products to use. 

Is Chalk Paint Waterproof?

No, chalk paint is not waterproof. It is classified as water-resistant, but there is an important distinction between the two. If you have some furniture painted with chalk paint in the house and you spill a small amount of liquid on it, you don’t need to worry. That doesn’t mean that it is completely waterproof though, and it will not stand up to constant exposure to rain. It’s just the same as a watch that will not break in the rain, but will if you go swimming with it on, for example.

If it is rained on for an extended period, the paint will start to run and your nicely painted furniture will turn into a complete mess.

Is Chalk Paint UV Resistant? FolkArt Home Decor Chalk Furniture & Craft Paint in Assorted Colors, 8 ounce, Cottage White

No, chalk paint is not particularly UV resistant. Over time, the sun will cause the paint to fade and crack. This is less of an issue if you are using it for indoor furniture that doesn’t get a lot of direct sunlight. However, if you put it outdoors, the sun will be a real issue.

Can You Use Chalk Paint Outside?

Chalk paint isn’t waterproof or UV resistant, so you could be forgiven for assuming that you can’t use it outside. That isn’t exactly right because you can use chalk paint outdoors, you just need to seal it first.

There is often confusion here because Annie Sloan, creator of chalk paint, says on her website that the paint is suitable for use indoors and outdoors and you shouldn’t need any sealer. However, you can also buy Annie Sloan Lacquer to seal your chalk paint, so do you need it or not? The confusion arises because it depends on the surface and whether it is vertical or horizontal.

The rain will run off vertical surfaces right away, so it doesn’t do as much damage. On horizontal surfaces, the water pools and soaks in, so a clear coat is necessary. Having said that, I would recommend using a clear coat on any chalk paint outside if you want it to last longer.

Once the paint has dried, you can put a clear sealer over the top. This creates a barrier to stop rain from damaging the paint. They can protect against mold and mildew too. Many sealers also have UV inhibitors built in, so they stop the paint from fading in the sun.

What are the Best Sealers for Using Chalk Paint Outdoors?

If you want to seal chalk paint for outdoor use, these are some of the best products to use:

1. General Finishes Exterior 450 Water Based Topcoat General Finishes Exterior 450 Water Based Topcoat, 1 Gallon, Satin

This General Finishes Exterior 450 Water Based Topcoat is a great matte finish that will protect your chalk painted furniture for years to come. It has  UV absorbers to protect against the sun (although some fading will occur eventually). The built-in mildewcide will stop any mold growth too, and it forms a solid barrier against the rain.

It’s quick to apply and it dries very quickly, so avoid using it in hot weather or you’ll end up with dragging and drips. Ideally, you should do at least 2 coats but if you add a few more, you’ll get longer lasting protection. This is a water-based finish too, so cleanup is simple too.

2. Helmsman Spar Urethane by Minwax Minwax 710520000 Water Based Helmsman Spar Urethane, gallon, Satin

Spar Urethane is one of the best clear coats for exterior projects. The Helmsman Spar Urethane by Minwax is one of the most reliable options on the market right now and it can be used for all sorts, including protecting chalk paint. It creates a very durable barrier against the rain and the UV inhibitors are excellent for preventing fading and cracking. It’s flexible too, so it won’t crack as the wood expands and contracts between seasons.

This is a semi-gloss finish, so if you want something completely matte, the General Finishes topcoat is probably better. But if it’s durability and longevity that you are after, spar urethane is the way to go. You may need to do 5 or 6 coats but it’s worth it because you won’t need to reapply for a long while.

3. Dixie Belle Paint Company Gator Hide Dixie Belle Paint Company (Satin Clear Coat) Use with Chalk Finish Furniture Paint (16oz)

Other options on this list are multi-purpose clear coats that can be used on painted wood, but are not specifically designed for that. Dixie Belle Paint Company Gator Hide is a great product that is specifically designed for protecting painted furniture and other similar items. It goes on fairly easily but be careful that you don’t layer it on too thick or you will get streaks. More thin layers will give you a better finish, especially with a light sand between each one. Using a foam roller is the best way to get a nice smooth finish.

This stuff goes a long way, so even though it comes in relatively small containers, one should be enough to do a few chairs or a large chest of drawers, for example.

4. Varathane Ultimate Spar Urethane Water Based Rust-Oleum 250041H Ultimate Spar Urethane Water Based, Quart, Gloss Finish

Varathane Ultimate Spar Urethane Water Based is another excellent spar urethane top coat you can use. This is a Rust-Oleum product, so you know it can be trusted to give you long-lasting protection against moisture and UV. It also dries very quickly so it will be touch dry in half an hour and ready to recoat in 2 hours. If you work quickly, you can get 3 coats done in a day easily.

Just bear in mind that although it says it dries completely clear, it can dry with a slight yellow tint. If you’re putting it over the top of white chalk paint, this might be an issue. It also takes on a slightly milky appearance when it gets wet, but this fades quickly. You’re unlikely to be using any outdoor furniture when it’s wet anyway, so you probably won’t notice this.

5. Retique It Exterior Marine Finish Top Coat Retique It Exterior Marine Finish Top Coat (32oz Quart, 2.Matte)

The Retique It Exterior Marine Finish Top Coat is a durable, water-based, ultra-low VOC coating that gives excellent protection. It’s a marine grade sealer, so it’s designed to stand up to extreme conditions. It contains 3 separate UV inhibitors too, so it is excellent at protecting against sun damage and fading. If you want a great eco-friendly option that still gives excellent protection, this is it.

How Seal Chalk Paint for Outdoor Use (Step-by-Step)

Once you have chosen a sealer for your chalk paint, follow these simple steps to apply it:

1. Make sure the paint is fully dry

First things first, make sure that your chalk paint is completely dry before you get started. Applying a water-based sealer to paint that has not cured properly will ruin the finish. It should take around 24 hours for the chalk paint to fully cure, then you can start sealing.

2. Clean away dust and debris S&T INC. 524601 Microfiber Cleaning Cloths, Reusable and Lint-Free Towels for Home, Kitchen and Auto, 50 Pack with Box, Assorted

Next, clean off any dust and debris so you get a smooth finish. You can use a clean paintbrush but a lint-free rag is best for removing all dust. 

3. Apply the first layer of sealer

Now you are ready to apply your sealer. Give it a good stir first because clear coats can sometimes separate with larger particles sinking to the bottom. You should also put a small amount of water on the sponge, brush, or roller you are using to apply it. 

Usually, it’s best to do thin layers of sealer to get an even finish and avoid any brush strokes and dragging. Always check the guidelines on the specific product you are using though, because every sealer is different. Make sure that you get into any small gaps so there is nowhere for moisture to get in at all.

4. Let it dry and sand the surface

Let it dry and sand the surface

When you are happy, you can let the sealer dry. Spar urethane will take around 4 hours to dry, but other clear coats will vary. Again, refer to the manufacturer’s guidelines for best results. When the first coat has dried, take a fine sandpaper (220 grit is good) and lightly sand the surface. You are only trying to scratch it up a little so the next coat bonds better, so there is no need to go overboard. After sanding, use your rag to remove any dust again.

5. Repeat for further coats

Finally, you can repeat steps 3 and 4 for each additional coat. When you have put the final coat on, there is no need to sand again. However, some people like to give a light sand to take the sheen off if they are using a glossy finish. Ideally, you should apply 4-6 coats to get a good protective layer, but some clear coats don’t require this many.

Avoid Oil-Based Sealers if You Want to Avoid Any Paint Discoloration

All of the products recommended above are water-based, and there is a reason for that. Oil-based sealers are more likely to discolor paints, especially lighter colors. The recommendations on this list all work great but if you want to try different products, that’s fine. Just make sure that you only use water-based products and not oil-based sealers.

Can I Use Furniture Wax to Protect Chalk Paint Outdoors? Clear Soft Finishing Wax to Seal and Protect Chalky Finish and Milk Painted Furniture. Eco- Friendly Beeswax Blend Will Not Yellow, No Harmful Fumes! Skin Safe, Matte Finish

Wax is often used over chalk paint on furniture, but if you are painting anything outdoors, it’s not recommended. The wax is great for protecting against general wear and tear and giving a nice finish. It also protects against the occasional splash of water, but it won’t hold up against heavy rain. Wax does not have UV protection either, so the paint will quickly fade. A sealer is a much better choice for protecting chalk paint outdoors.

Should You Leave Chalk Painted Furniture in the Rain?

The whole point of sealing your chalk paint is so that the rain doesn’t destroy it immediately. But that doesn’t mean that it is indestructible and if you leave in direct rain and sunlight for extended periods, the finish will degrade eventually. If you want to slow down that degradation and make your chalk paint last for longer, simply cover the furniture where possible.

You can put it under an awning or an umbrella if you have one. You should also store it inside during the winter, if possible. You won’t be using it much anyway, so keep it out of the rain and protect the finish and it will last you a lot longer.

Is Chalk Paint Designed to Be Used Outdoors?

No, chalk paint is not designed to be used outdoors on its own. It must be sealed properly if you are exposing it to the elements. But even then, you will possibly notice damage to the paint because it is getting more wear and tear than it should. This is fine, just be aware that you will need to maintain it with regular touch-ups, and keep on top of your sealer. 

Final Thoughts

Sealing chalk paint is crucial if you are using it outdoors. There are all sorts of great sealers available, including the ones listed above. Just make sure that you always go for a water-based product and you give it plenty of layers. Lots of thin layers are much better than one thick one, so a bit of patience is required here.

About the Author

Jamie

Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.