Is Latex Paint Waterproof? (& How To Make it)

Latex is a water-based paint that beautifies a surface. But, is latex paint waterproof, and does it protect wood?

Latex paint isn’t waterproof and offers minimal water resistance to surfaces. The paint will get washed off if exposed to constant water (or moisture). However, you can make it waterproof by applying a sealer over it.

Since latex paint penetrates the wood surface, it makes the surface water-resistant (to a degree). So, you can still wash and clean it (after it dries) with water. However, if exposed to constant water (for a few hours) its finish will get washed off. 

Why isn’t Latex Paint Waterproof?

Is Latex Paint Water-Resistant

Latex paint isn’t waterproof because it uses water as its paint solvent. Since it has already water in its formula, adding more water will only thin the paint. Being a water-based paint, latex paint is compatible with water and won’t repel it. 

For paint to be waterproof, the paint must repel constant water and moisture, and latex paint doesn’t do that. Latex paint has low water-resistant features, meaning it’s resistant to small amounts of water. So, you can clean it with water without damaging it. 

Also, waterproof paints have a glossy finish that repels (prevents) water from penetrating their surface. As a result, the water (or moisture) will slide off the glossy layer of the paint without soaking into the coating. However, latex paint has a dry textured finish, so the water won’t slide off the finish.

Latex paint has a fast drying time. This means the paint particles don’t have enough time to harden or get compact with each other. This means its isn’t durable (or compact) enough to prevent water from soaking. 

How To Make Latex Paint Waterproof?

How To Make Latex Paint Waterproof

To make latex paint waterproof, you must seal it with a waterproof sealant. The waterproof sealant will act as a “shield” for the paint and prevent water and oils from penetrating it. 

The sealant will form a clear glossy finish over the finish. This glossy layer will prevent water and moisture from getting through the sealant topcoat. Since water can’t penetrate the topcoat (sealer), it won’t get to the paint underneath.

Here’s how to seal latex paint: 

  1. Wait for latex paint to dry
  2. Sand (scuff) the paint with fine-grit sandpaper. 
  3. Apply 2-3 coats of waterproof sealer.
  4. Sand between coats of the waterproof sealer (except for the final coat).
  5. Let the waterproof sealer dry.

As a waterproof sealer, you can use polyurethane, varnish, or polycrylic. For outdoor surfaces, use exterior polyurethane or varnish. For indoor surfaces, use water-based (or oil-based) polyurethane, varnish, or polycrylic. 

You can also mix it with polyurethane before applying it. The mixture will provide a colorful glossy finish that is resistant to water. However, you can only mix it with water-based polyurethane. Don’t use oil-based polyurethane as they aren’t compatible. 

Rain Affects It

Rain does affect latex paint, especially if exposed to heavy or contact rainfall. If the finish is exposed to constant rain, it will wash off and won’t last more than one week. That’s because latex paint isn’t waterproof. 

Since it isn’t waterproof, the paint won’t be able to prevent the rain (or water) from penetrating the surface. However, if the paint isn’t exposed to constant rainfall, the finish will last a couple of months before it gets washed off. That’s because it is resistant to low amounts of water. So, a low amount of water will evaporate rather than soak into the finish.

Latex paint offers low moisture-resistant features. This is because the paint soaks into the wood pores to stick, and since the wood pores are already filled with paint, the water won’t penetrate them and will stay over the top layer. 

Also, rain tends to affect the finish on horizontal surfaces more than on vertical surfaces. That’s because horizontal surfaces, such as table tops, are exposed to water more. Also, the water will stay over the vertical surfaces for longer. On the other hand, water will slide off the vertical surfaces and won’t affect the finish as much. 

Final Words

Latex paint has low water resistance features, but the paint isn’t waterproof. If you apply it on a surface exposed to constant water, the paint will wash off.

To make latex paint waterproof, seal it with a waterproof sealant. 

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