What Happens When You Add Water To Latex-Based Paint?

Although it requires a great deal of planning and precision, there's nothing like painting one or several rooms in your house, enlivening the environment with a different color or just giving your walls a fresh coat. However, if you're new to home painting we want you to arrive at the paint store as prepared as possible and not make common mistakes while you're there, like getting the wrong paint or brushes. 

You probably know that you have two basic paint choices — oil-based or water-based — and water-based paints are also known as "latex." Amateurs and pros alike use petroleum products like mineral spirits to thin oil-based paints and water to thin latex paints. However, it's customary at the store for the paint to be vigorously shaken to mix it up, not only to create the precise color but to blend the various paint compounds together. Mixed paint is ready to be used; and, in the case of latex, it most likely won't need to be thinned.

The reason you generally don't want to thin latex is that it might result in a lower-quality finish. When you add water to latex, it lightens the color. The swatch you lived with and the color you originally fell in love with might be completely different when you add water. Mixing water into your paint will also create bubbles, so you need to let it settle before using it. Finally, according to one of Sherwin-Williams' training center blogs, adding water to latex degrades its performance because the resultingly thinner product simply won't be as durable as originally intended and formulated.  

So, if latex paints are actually ready to go when you get them home, what are the reasons they would need to be thinned? Well, it depends on how you're applying the paint and whether you're using a previously opened can.

First, here's why you'd need to add water to latex to thin it. If you're a pro-level DIYer, you might be comfortable using a paint sprayer. Paint sprayers require thinner paint to work properly because the regular viscosity of latex is too thick. In that case, you'd need to add water so that the sprayer is capable of creating a seamless finish. 

Second, if you've already cracked open your latex paint and it's been sitting around for a while and air got into the can, some of the liquid evaporated, requiring a water resuscitation. In this case, diluting the paint by adding water would bring it back to its original consistency.