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Waterproofing Clay Pots: Using Thompson’s Water Seal on Terracotta

This post shares tips about how to seal clay pots for painting. If you’re wondering if waterproofing clay pots is an effective way to preserve a paint job, it is! I’ll walk you through using Thompson’s Water Seal on terracotta pots.

How to seal clay pots for painting & using Thompson’s Water Seal on terracotta!

Hey folks, today I’m chatting about how to seal clay pots for painting. Waterproofing clay pots is an essential step to complete before painting your pots, and it helps to preserve your paint job. And using Thompson’s Water Seal on terracotta is a great option.

This post specifically focuses on painting clay pots for outdoor use, but I follow a really similar process for painting pots for indoor use. Check out my detailed post about waterproofing indoor clay pots and painting them with acrylic paint. Outdoors, I’m doing a bit of painting for some of the container veggies and plants I’m planning for the backyard, so I’m putting this sealer to work lately.

If you need to strip old paint from your pots first, check out my tutorial on how to remove chipped paint from clay pots before painting them. (That project uses Thompson’s Waterseal in an aerosol version.)

Want more outdoor posts? See my full backyard post here! I also have a post about how to clean an outdoor rug, how to build an outdoor coffee table using concrete pavers, and my review of using Ready Seal to stain and seal our fence.

gloved hand holding small terracotta pots
Bare, unsealed terracotta pots.

Do you need to seal clay pots before painting?

Yes. I have painted a lot of terracotta pots for both indoor and outdoor use. And I have yet to find a paint that stands up to its claim to be a sealer and paint in one. And that includes the outdoor paints I’ve used—the ones that claim you do not need to use a sealer. Here’s why.

Terracotta is, by nature. extremely porous. The terracotta soaks in excess water from the soil to help protect the roots. Then, the soil is able to dry out faster. This helps to prevent overwatering, but it can sometimes lead to a lack of moisture and caked, shrinking soil if you’re not careful.

So when you seal terracotta, you are giving up some of the benefits that terracotta has for plants. I haven’t had any issues with the plants in my sealed and painted pots—it’s just something to keep in mind. You do need to seal clay pots if you’re painting them, though. Because terracotta is so porous that it will take in all of that extra moisture and lead your paint job to bubble, crack, and peel.

Even sealing terracotta pots before painting them isn’t a permanent solution, though. Water can do a lot of damage, as can the elements (sun, rain, etc.). Waterproofing clay pots is a good way to lengthen the life of your painted pots. Bringing them indoors or putting them in sheds during the fall and winter helps, too.

painting a terracotta pot
white painted planter chipping from the elements
Even after sealing and painting this pot, a few seasons of sun, rain, and living outdoors all year round led to chipping and peeling.
white painted planter chipping from the elements
Here is the pot when I was sanding it down to reseal and repaint.

About Thompson’s Waterseal Clear Multi-Surface Waterproofer 

So what do I use to seal pots? Here’s a bit about the waterproofer and why it’s my product of choice to seal clay pots for outdoor use:

  • The Thompson’s Waterseal website indicates that it will effectively seal any porous material against damage by water, including concrete, brick, stone, plaster, wood, canvas, and asbestos. So I figured it would be up to the task of sealing clay.
  • It’s clear and has a nice consistency. It’s pretty watery, a lot like a water-based polycrilic if you’ve used that. When painting on clay, it’s easy to see where you’ve painted because it just makes the pot look wet.
  • It doesn’t have a terribly strong odor, and the odor it does have dissipates pretty quickly. Even when I painted in the garage.

We have a 1.2 gallon jug of this stuff, but it’s also available in a quart option and a handy aerosol spray for smaller projects. I use a disposable chip brush when working with this sealer so that I can just chuck it when I’m done and not have to deal with mineral spirits cleanup.

I used Thompson’s Waterseal Clear Multi-Surface Waterproofer first on the very large pot in the pic with the snake plant below. Even though I did use a paint designed for outdoor use on this pot, the clay was super porous, and I was afraid it wouldn’t stand up to the elements (and the moisture of a ton of wet soil on the inside).

thompson's waterseal can
large clay pot painted white outside

The best place to buy big clay pots for cheap

Now we know why to seal clay pots before painting them and what to use…but where do you get a big clay pot? Big pots are EXPENSIVE. Go to any home decor or big box store and you’ll fall in love with a pot, only to have your yikes meter run off the charts when you see the price.

But big pots are also very pretty—and necessary if you’re planting something that needs a bit of room. Enter Ollie’s Bargain Outlet. One of my favorite stores…and DEFINITELY a favorite for pots. In the spring and summer, they have a buttload of pots to choose from. And they aren’t cheap plastic ones, either.

They are beautiful clay pots, many of which are also glazed. Just yesterday I came home with three giant pots. One for $20 (black glazed), one for $12 (blue patterned one), and one for $10—the yellow beaut I’m going to be working on in this post.

large beautiful pot
large beautiful pots  nd plants

Waterproofing clay pots with Thompson’s Water Seal

So this yellow one…I loved the lines on it and the size was perfect for the space I wanted. The yellow just wasn’t going to cut it, though, so I decided to break out some paint. I really wanted to do this pot in a navy color for the backyard.

However, when I got out my royal blue and black outdoor paints to mix together, I realized that I hadn’t completely shut the blue when I’d opened it last. Noooo. It was ruined. Super chunky and totally unusable.

I really had my heart set on navy, but I decided to take the easy way out and use the white I already had on hand: DecoArt Curb Appeal in Farmhouse White. It would look nice next to the white pots I already had near the area this pot was going. And it would help tie in the bright white trim on the deck a bit more.

waterproofing and painting a clay pot

Sealing this bad boy

So to seal this pot, I just brushed on the Thompson’s Waterseal Clear Multi-Surface Waterproofer using a chip brush. I did a few coats on the inside and outside of the pot since both sides were unsealed. The instructions on the water seal say to wait a while before painting over it, so I officially recommend that strategy. 🙂

However, I did not follow the directions because I am impulsive and impatient. I left it to dry overnight under a fan and painted the next day. Here’s the first coat of white paint brushed on—I did two coats. And then the lovely finished pot, sealed and painted for a beautiful fit in my space.

painting a clay pot white
a photo of a painted white pot in a backyard
Beautiful outdoor setting with plants and flowers
a photo of a painted white pot

If you like outdoor DIY projects, make sure to check out my DIY AC unit screen, my DIY paver side table, my modern trellis for a vining plant, and my roundup of vertical and container gardening ideas.

Pin my tips about waterproofing clay pots using Thompson’s Water Seal!

collage that says how to seal clay pots before painting

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  1. SHEAN says:

    Thanks for sharing these, Looks like a lot of great ideas…I’ll have to come back & look more closely very soon!:)

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