Two years ago, I helped my Great Aunt clean out her basement, and in return, was gifted the miscellaneous cans of paint we found.
I’m fairly confident my grandfather was the one who stored the paint there, and since he died a decade ago.. well, it’s old. And thick. And goopy. But luckily, latex paint is easy to thin!
To thin latex paint add a half cup of water per gallon of paint. Stir well with a stick that reaches the bottom of the container. For oil-based paint, thin with mineral spirits or turpentine in a one-to-three ratio.
But sometimes there’s a bit more too it, so let’s dive in!
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How to Tell if Paint is Too Thick
Paint should be about the thickness of room-temperature maple syrup. It’s thick, but still runs smoothly and easily. If that’s the consistency you’ve got, then unless you’re planning to spray the paint, you should be good to go.
If your paint is thicker or has globs falling off the paint stirrer even after a thorough stirring, then it needs to be thinned, else you risk a bumpy, uneven finish.
Additionally, even if your paint is smooth and the correct consistency, if you’re putting it into a paint sprayer, it needs to be thinned further. Otherwise, the paint will clog the sprayer, and you’ll constantly be taking it apart to declog.
How to Fix Paint That’s Too Thick
Step 1: Find a Bucket Large Enough for All of Your Paint
If you’re thinning paint, you’ll want to thin all the paint you’ll need in one go. Since thinning the paint will slightly lighten the color, this will ensure you end up with a consistent batch.
Therefore, you’re going to need a pretty big bucket.
If you’re only using one gallon, don’t be tempted to mix the water and paint in the original one-gallon pail.
Trust me. You won’t have enough space, and even if you’re super careful about spilling, you still won’t have mixed everything well enough because you were trying so hard not to make a mess.
Ask me how I know.
Step 2: Add Water (or Mineral Spirits for Oil-Based Paint)
If you’re using latex paint, water will work to thin the paint. If you’re working with oil-based paints, mineral spirits is your best bet.*
The actual amount recommended for thinning paint varies on the manufacturer and paint type (I talk more about this in this post,) but for latex paint, a half cup per gallon is the general guide.
Keep in mind that you don’t need to add the full amount all at once. The less water you add, the more durable your paint will be, so it’s in your best interest to add only the water that’s needed to get the paint to the correct consistency.
Start small, stir, and then try again if the paint is still too thick.
This is also the technique I recommend for oil-based paints, using mineral spirits or paint thinner instead of water.
*Important Note: Never thin oil-based paints with water (or latex paint with mineral spirits.) Oil and water do not mix, and you’ll ruin the paint if you try.
If you’re not sure which type of paint you’re working with, check the cleanup instructions on the can. Latex paint cleans up with water. Oil-based paint cleans up with mineral spirits.
Step 3: Stir the Paint Thoroughly
This is one of those times that you’ll want to make sure you do an excellent job stirring, else you’ll end up with weird, slightly darker streaks in your paint job.
I’ve got a couple tips for this. First off, set a timer for 3 minutes. Stir the entire three minutes, which is annoying, but really ensures you do a good job.
As you stir, make sure you’re scraping the sides and bottom of the container. Otherwise, old, unmixed paint sticks to them, showing up as a different color in your final piece.
Scrape the stir stick sometimes too. Basically, we want to avoid having unmixed paint hide out anywhere.
Pro Tip: If you’re feeling really fancy, and you’ve got a plenty of space in your container, you could also stir the paint with a mixing paddle attached to a drill.
And if you don’t want to buy a mixing paddle… here’s a not-so-pro tip – the egg beater paddle from a handheld kitchen mixer works too, given your paint isn’t all that deep.
Step 4: Test
You could paint some scrap wood, but most of the time I just lift the stir stick out of the bucket and watch the paint fall back into the can.
Too thick? Add more water, although if you’ve hit the 1/2 cup per gallon limit, you’ll risk reducing the durability of the paint. (On the other hand, there are some awesome techniques that use really thinned paint.)
Too thin? Add some paint back in!