Physics of Oil and Acrylic
Katie LiddiardEver wondered whether you can slap some acrylic paint over a beautifully prepped oil ground? Spoiler alert: don’t do it. Let’s unpack why.
In this eye-opening lesson, artist Katie Liddiard breaks down the science behind why oil and water (or oil and acrylic) just don’t mix. Using a fun and simple demo with oil and water, she explains how oil paint, which is oil-based, and acrylic, which is water-based, behave like rival siblings who just can’t get along. It’s not just a matter of preference, it’s chemistry. Oil sits on top of water because it's less dense, and that same principle plays out on your canvas.
Katie shows a real oil-primed linen panel and discusses why acrylic can’t be layered on top of it. The acrylic simply can’t adhere properly—it will delaminate, lifting away from the surface over time and eventually causing the painting to fail completely. Yikes.
But don’t worry, Katie doesn’t leave you hanging. She explains what does work: acrylic ground (like acrylic gesso) can be used under both acrylic and oil paint. Oil ground, however, should only be used under oil paint. She shares her own preference for a lead oil ground due to its lower absorbency, which helps her oil paint glide and last.
The big takeaway? Always know what’s beneath your painting. Whether it’s a store-bought canvas or a hand-primed panel, being aware of your materials gives you confidence—and keeps your masterpiece safe for years to come.
If you’ve ever stood in front of your canvas wondering what your ground is made of, this lesson is for you.
Katie makes the science approachable, the advice practical, and the message clear: when in doubt, check before you paint!
Can you paint acrylic paint on top of an oil ground on your canvas? I actually get this question quite a lot, so let's talk about it today. I'm Katie Lydiard. Let's talk about the physics of oil paint and acrylic paint and see what you can and cannot do in terms of these two mediums together. I have a simple demonstration here set up.
I have my oil and I have my water. Of course, acrylic is water-based and oil paint is oil-based. It doesn't matter the oil, it's going to be the exact same no matter what, and we've all done this in school where you have your water, right, and oil is just going to be less dense than water, and so. It looks like it can go down beneath the water, but then it's ultimately going to sit right on top every time. It's the same thing with paint you can have.
Oil paint and acrylic paint. This is acrylic, this is oil. But you cannot put the acrylic on top of the oil. So when you have a ground like this here, this canvas, this is the bare ground. You have the linen underneath and then it's been primed with an oil ground and that's why I cannot paint acrylic on top of the oil ground.
I need to know every time I use a panel, a canvas. Whatever it has been prepped with, you can use an acrylic ground for an acrylic painting. You can use an acrylic ground for an oil painting, but you cannot use an oil ground for an acrylic painting. What will ultimately happen is the painting layer will actually delaminate from the ground, from your panel, from your canvas, and then. You don't have a painting anymore basically it's not supported by anything at that point.
It is completely separating from its support, so keep that in mind. Know what's in your, your paints know what's in your substrates know what's all around, what your materials are made out of and what you can do with them because you don't want to be in a situation where you just don't have a painting anymore. Acrylic gesso is great. A lot of people use acrylic gesso, and if you stick with that, I don't like it just because it tends to be really absorbent with my oil paint, but with acrylic, it's fantastic. And with my oil paint, I like to use an oil base.
Ground just because it's less absorbent, and I like to use a lead oil-based ground so that I have a lot less absorbency into my ground, and I know that my materials are going to work together instead of separate from each other. So keep that in mind as you start your next masterpiece.
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