Here are some general tips for Milk Paint. I promise it is not that hard, once you get your head around it, you will LOVE it.
The thickness of the paint really is a preference thing. If I’m painting raw wood, I’ll mix it thinner, because it will soak into the grain of the wood. If I’m painting something with an existing finish or paint, I’ll mix it a little thicker, since it will be sitting on top of the surface. It should always flow nicely off the brush, though.
Different colors mix differently. I have found that the lighter colors usually need less water. Tricycle (red) is the most challenging color to mix, since the red pigments resist the water. This is a perfect color to use an electric mixer on or to shake in a lidded jar. It will come together, if you mix it by hand, but if that’s the first color you ever mix, just know that most colors mix easier!
The pigments in some of the colors separate, especially the ones with yellow and blue pigment, like Boxwood. This can be problematic if you’re painting a larger piece and don’t stir a little as you go. The paint will look more yellow or more blue towards the end, resulting in a splotchy, uneven look. This won’t happen if you give the paint a little stir, even just with your brush, every ten minutes or so.
The kind of water you use can make a difference. I use ordinary tap water, but if you have well water or really hard water, you may want to consider using bottled for mixing your milk paint.
You may find that the paint thickens as you use it. That is because the brush is drawing more water out of your cup or container, so you may need to add a little more water and give it another stir.
Once mixed, the paint can be stored for about a week. Just cover it with plastic wrap or a lid and keep it at room temperature. When you’re ready to use it again, mix it and add some more water to bring it to the right consistency.
You can mix two or more colors to make custom colors! I like to mix up small batches, writing down the “recipe” until I find the color I want.