Sometimes, you want to paint but it starts to rain. So, can you paint wet wood?
You can paint wet wood if you do enough prep work and use water-based paint. You must dry the wood as much as possible using paper towels, a hair dryer, and a fan. After, you must apply a stain-blocking primer and two coats of water-based paint.
Since water-based paint uses water as its solvent, the paint will soak into a wet surface. Don’t use oil-based paint, as the oils in the paint will not stick or be absorbed in the damp wood.
However, the finish quality will be bad and the paint might not stick, so you shouldn’t do it unless there’s no other option.
Does Paint Stick To Wet Wood?
Paint doesn’t stick well to wet wood because moisture will prevent proper paint adhesion.
When the surface is wet, the fibers absorb water and tannins. The wood fibers that have absorbed water won’t absorb the paint since they are filled with water. Since they can’t absorb it, the paint won’t be able to penetrate its surface so it won’t stick.
Instead of sticking, the paint will stay over the top layer and develop bubbles as the paint mixes with the water. However, you can improve the paint adhesion by applying a moisture-resistant or waterproof primer on the wood before applying the paint.
A waterproof primer will prevent the moisture or water in the wood from bleeding through the coating. This way, the paint will stick better since it’s applied on the dry primer coating and not directly on the wet surface.
Moisture Prevents Paint Adhesion
The moisture on the surface will prevent the paint from penetrating the surface and sticking,
Moisture in the wood isn’t just water; it can be a mixture of water, tannins, and oil. So, the finish can develop stained spots and patches if moisture bleeds through it.
The water can also mix with paint and thin it. As a result, the paint will be lighter, start to drip off, and have a poor color shade once it dries.
When you paint over damp wood, the paint will take longer to dry. That’s because except for the paint solvent, the moisture also must evaporate for the finish to dry, which takes a long time.
Once the paint dries, it won’t last long because it will be affected by moisture, dust, and other factors that damage it. So even if you do enough prep work, the paint won’t be durable, and it can come off with minimum force.
Test Moisture Levels First
To know if the wood is dry enough for painting, test the moisture content using a portable moisture meter. A moisture meter will test and show how much moisture is on a surface
To use a moisture meter, insert its prongs into the surface. The prongs are the needle-like objects at the top of the meter. After inserting them, the moisture content of the surface will be displayed on the screen of the meter.
The moisture content must be less than 15% for the paint to stick to the wood. So, if the meter screen shows a lower percentage than 15%, you can paint it. For interior wood, the moisture content must be lower than 12% because the surface isn’t exposed to sun or dry air like outdoor surfaces, so it dries slower.
Using the water test, you can know if the surface is dry enough. Sprinkle some water over the surface. If it absorbs the water fast, the surface is dry enough. If it doesn’t absorb the water, it means the wood fibers are filled with water and can’t absorb more liquid.
Wood Dry Time Before Painting
Wood must dry for at least 1 day before painting it. But, if it has absorbed too much water, it must dry for 1 week.
For wood to dry, the moisture inside it must evaporate. So, its dry time depends on the type of wood, how much moisture it absorbed, and the ambient temperature.
For instance, softwood and thin plywood dry faster than hardwood because they are thinner, so the evaporation rate is faster. You must let them dry for 3 days.
The amount of water absorbed also matters. The higher the moisture content, the longer it takes wood to dry. The moisture must be lower than 15% for the paint to stick; this can take several days, depending on how much moisture is there.
The ambient temperature also determines the dry time. If the surface is placed outdoors, it will dry faster because it will be exposed to heat and UV rays, increasing the evaporation rate. As a result, outdoor surfaces can dry within 1 day.
If the wood is placed indoors, the ambient temperature will be lower, so it will take longer to dry. On average, indoor wood must dry at least one week before painting.
If the surface was power-washed, you must let it dry for 3 days because it has a high moisture content.
How To Speed Up Wood Drying Time?
Here are a few methods to use to make it dry faster:
1. Use a Hairdryer
The faster the water evaporates, the faster the surface dries. To increase the evaporation rate, you can increase the heat around the surface using a hairdryer or heater.
Here’s how to do it:
- Plug and turn on the hairdryer.
- Set the temperature to low or medium heat.
- Move the hairdryer around the damp surface for a few minutes.
- Turn off the hairdryer to let it cool down.
- Repeat this process every 2 hours.
2. Use an Electric Fan
Electric fans can make thin and softwood dry faster because it produces air that helps woods that air-dry dry faster.
To use an electric fan, turn it on and direct it toward the surface. Then leave it for as long as possible.
3. Use Paper Towels
Paper towels will absorb the water on the top layer of the surface. To use this method, rub the surface with paper towels continuously.
However, this method works only for small pieces.
4. Expose the Wood to Sunlight
Nothing dries a surface faster than sunlight. Simply put the item outdoors under direct sunlight for a few days. The heat from the sun will evaporate the moisture and dry the surface.
However, this might take a few days.
Paint Type for Damp Wood
It’s recommended to use water-based paint from damp surfaces. That’s because they use water as their solvent so they are compatible. However, if there’s too much water on the surface, the water-based paint will get removed or over-thinned and won’t stick. So, only use it if the moisture levels are lower than 12-15%.
Avoid using oil-based paint over damp surfaces because the water in the surface isn’t compatible with the oils. Since they aren’t compatible, the oil-based paint won’t stick and can turn sticky.
Related Read: How To Spray Paint Wood?
Priming or Sealing?
You can prime over wet surfaces using a moisture-blocking primer. A stain-blocking or moisture primer will prevent moisture (or water) from bleeding through.
The water will affect most types of primer so it’s best to use a shellac-based primer. The primer also creates a smooth and dry surface for the paint to stick.
Seal Wet Wood
You can seal wet wood, but you shouldn’t. When dry, a sealer will create a thick and glossy layer that repels any moisture. However, if there’s moisture still under it, the moisture will get trapped inside the sealer and rot the wood.
So, you must wait until the surface is dry to use a sealer. However, if you must use a sealer, you should use waterproof sealants because these sealants won’t be affected by moisture.
It’s possible to paint over damp wood, but you must get its surface as dry as possible and use a moisture-blocking primer before applying paint.
You can speed up its drying time by using a hair dryer, paper towels, an electric fan, or placing it outdoors.
Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,