Oil paints are often used to create textures in paintings. But, there are also times when you need to thin out your paints, especially if you are painting in layers.
There are several different ways to thin oil paint. The method you choose will depend on three factors:
- your oil painting technique
- how thin you need the paint to be
- and how glossy you want the finished product to be.
You can use a variety of solvents to thin oil paint. These solvents will also help the paint to dry faster, and make the finish quite glossy.
In this post we are going to take a look at a few ways to thin oil based paint, and how to use these methods. Let’s get started.
#1. Thin Oil Paint Using Oil Paint Thinners
The most effective and easiest way to thin oil paint is by using thinner for oil paints. I usually use turpentine, but you can also use mineral spirits for this purpose.
For specific details, check my guide on “what is paint thinner“.
Solvents will act quickly to thin the paint, and they are low viscosity, which simply means that they are a bit watery. A small amount of solvent will give the paint a buttery texture.
Or, you can use more to make it more watery. This will allow you to cover the canvas while using much less paint, so you will be saving money by thinning your paint.
One of the things I like about using solvents is that they help the oil paint to dry faster than if you were to thin out the paint using natural oils. Solvents are also a lot less expensive than other mediums.
The Fat Over Lean Rule
When painting with oils, it is best to paint in layers. When using the fat over lean rule, the thinnest layer would be first, and the subsequent layers would be thicker. This prevents “sinking in”, which causes dull spots to show up after your work has dried.
Each layer of paint should use less solvents than the previous layers. That way you know there is going to be more oil in each layer, and this will keep the paint from sinking in.
If you are using an oil paint that is very thick or particularly oily, or if you are using a glazing technique, try to avoid using solvents. In these cases, it is best to use oils or mediums made with oils.
Beware of Fumes
There is one major downside to using solvents, especially turpentine, and that is the fact that they give off harsh fumes. This is not good for anyone who suffers from allergies or respiratory issues.
I always tell my paint and sip students to make sure that they work in a well-ventilated area when working with oil paints for this very reason.
#2. Thin Oil Paint Using Oils
Many artists choose to thin their oil paints with more oils. This is going to cause a higher viscosity, and the paint will have a glossier finish when it is dry.
When using oils to thin oil paints, make sure that your first layer of paint is not thinned out unless you are going to be using as much or more oil in the rest of the layers. This will prevent sinking in.
If you prefer working with thinner paint, as I often do, the first couple of layers should be thinned with solvents. The rest of the layers can be thinned with oils or oil-based mediums.
Here are the most popular oils to use for thinning oil paints.
Linseed oil seems to be the most popular oil for painting, and it is one that I often used. It is made from flax, and it is very stable.
This type of oil has a moderate drying time, so you can expect your painting to be mostly dry within five to seven days. It dries by creating a top layer of “skin”, and then it dries downward from there.
The only thing I don’t like about using linseed oil is that it can turn yellow after a while.
Stand oil is linseed oil that has been heated. This creates an oil that is thicker and has a higher viscosity. It also dries faster than traditional linseed oil.
Because stand oil dries quicker, it doesn’t require as much oxygen. It is the oxygen that turns other oils yellow, and you won’t find that to be as much of a problem with stand oil.
Walnut oil is another popular choice among artists. This is because it doesn’t tend to turn yellow, and it doesn’t crack easily. But, if you want your painting to dry quickly, this is not the oil to use.
Some paint manufacturers only use walnut oil for their oil paints. This type of oil is great if you want to have really intense colors in your painting.
Safflower oil is great for thinning paint, but it does dry quite slowly. Unlike linseed oil, which dries by forming a skin first, this oil tends to dry more evenly. It will feel quite sticky as it is drying.
Safflower doesn’t turn yellow as linseed oil does, but it may not be the most stable oil if you want your paintings to last for many years.
If you aren’t worried about your painting drying fast, or you want it to dry slowly, poppy oil is the best choice. Again, there are problems with the stability of this oil, and it may not be the best option for the initial layers of any oil painting.
#3. Thin Oil Paint Using Mediums
There are many mediums you can use to thin your oil paints. These mediums are available in most places that sell art supplies.
In most cases, mediums are a combination of solvent and an oil-based substance, such as petroleum distillate. Some of the most popular mediums to use for thinning oil paints include Galkyd and Liquin.
These are just a few of the ways you can thin out your oil paints. You may also be interested in trying gels, which are high viscosity. If you are using thick paint applications, such as with the Impasto technique, I recommend giving gels a try.
You can also play around with combining solvents and oils or mediums and see what kinds of results you end up with. For instance, mixing mineral spirits with stand oil will give you paint that is low-viscosity, dries quickly, and has a glossy shine.
I always tell paint and sip guests to play around with different ways of thinning paints to find the method that works best for them, and I offer this same advice to you.
- How to make oil paint thicker
- Do You Need Paint Thinner for Paint and Sip?
- How to thin acrylic paint for canvas
*image by K1tyara/depositphotos
Sari Green is a semi-professional artist and professional writer. She has been hosting paint & sip parties for the past couple of years, and truly enjoys helping other people to create their very own masterpieces. She loves to create, and you never know what she’s going to come up with next!