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Oil Painting Basics, Mediums Part 1: What is an Oil Painting Medium, How are they Used, and Which is the Best Medium?

Updated: Jun 12

When I first started to paint with oil paints, one of the more confusing and frustrating aspects of oil painting were the mediums. How was I supposed to use them? Which one was the best? Why are there so many options? Etc, etc.

I have decided to break this topic down into two parts: Part 1 will cover the basics of oil mediums and a few "easy to use" options; Part 2 will be on various traditional oil mediums and solvents, as well as some new non-toxic and solvent free options.

Here, in Part 1, I will be covering the following:

What is a medium?

How do you use mediums?

What are the easiest mediums to use?

What is my personal preference?

What is a Medium?

A traditional painting medium is a mix of an oil and a thinner (such as turpenoid) and can do the following when added to oil paints:

- extend your oil paints to cover more area

- quicken or retard the drying time of your paints

- modify the texture of your oil paint, making it thinner or thicker

- alter the paint's sheen, making it high gloss, satin, or matte

For me, the easiest way to think about why we use a medium in oil paint is comparing it to watercolors. Oil Mediums do the same thing for oil paints that water does for watercolors. Water is the basic medium used to change the consistency of the watercolor paint, just as oil is the basic medium used to change the consistency of oil paint.

How do we use Mediums?

How much medium to use is a hard question to answer. A lot of it comes down to feel, but less is more. The highest ratio of medium to paint you will want is about 1 part medium to 3 parts oil paint. Anything more than that and the paint will start to break down and to bead on your canvas.

There is also the golden rule of mediums, and that is fat over lean. Below I will discuss this rule in regards to "premade" mediums, but I will be making an entirely separate post about this topic later.

For now, in the video below you will see how I use my mediums. At the beginning of a painting session I drop about five drops of medium and oil onto my palette. However, if I am covering a large amount of the canvas with the same color, say a background, I will put my medium directly into my paint mixture.

VIDEO (video to come)

As you can see, you really don't need a lot of medium to get your paint to do what you want it to do. Again, less is more.

What are the easiest mediums to use?

Premade mediums are amazing. Traditioanl mediums require a mixture of both solvents and oils in varying ratios. With premade mediums you can just use them without having to alter them.

Three of the best premade mediums are: Winsor and Newton's Liquin Original, Gamblin's Galkyd, or M. Graham's Walnut Alkyd Medium.

While there are so many more, it is hard to go wrong with one of these three. Let's go over each and their pros and cons.

Liquin Original

Pros: Creates a great hard film for your painting. Meaning that as it dries, the paint cannot be easily lifted in subsequent layers. Liquin leaves a nice shine, and you will almost never have dull spots. It is a gel like substance that you just scoop out with a palette knife, put on your palette, and dip your brush into when needed. Mixing directly into large amounts of slow drying paint, like titanium white, will speed up drying time. This was the first medium introduced to me and it is great option for both thin and thick paint application.

You can add liquin to any oil in order to extend its drying time. You can also add solvents like turpentine or mineral spirits to speed up its drying time, but liquin dries so quickly that this is not necessary.

Cons: It is so smelly. Do not use in a closed room and do not use around pets and children. It is very toxic. Purchase a small bottle as first, because once open the liquin inside the bottle will start to dry out.

You can read more about liquin here.


Pros: Like liquin, creates a great hard, glossy film for your painting. It leaves a nice shine, and you almost never have dull spots. Thin layers of paint will be dry to the touch within 24 hours. It is also not smelly, as it is made with Gamsol Odorless Spirits. Use a dropper to put 5-10 drops onto your palette at a time, dip your brush in when needed, or mix directly into large amounts of paint.

You can add oils and solvents to length or shorten drying times, but, like liquin, it dries so quickly this is unnecessary.

Cons: While it is made of some of the best, odorless spirits, it is still made with a solvent and is still toxic. Do not use in a closed room, even though the smell is not bad, and keep out of reach of pets and children. It is also thicker than our other two options. I find it too thick and prefer to use galkyd lite. However, galkyd lite will not retain brush strokes like the original galkyd.

Below is a slightly boring, but very useful video about Gamblin's galkyds.

Walnut Alkyd Medium

Pros: Non-toxic and eco-friendly. It is solvent free and decreases drying times, but slower than the other two options. It leaves paints with a matte-ish finish, and can easily be combined with M. Graham's walnut oil, or any oil, to extend drying time. Use a dropper to put 5-10 drops onto your palette, dip your brush when needed, or mix directly into large amounts of paint.

Cons: The painting surface does not dry hard and can leave you with dull spots. I find that mixing equal amounts of Alkyd with oil (I use their walnut oil), can help lessen dull spots. Because the painting surface is so delicate when using this medium, you cannot oil out easily (more on what oiling out is in another post), other wise the paint will lift. You can use it in a closed room and it is safe to be around pets and children (however, you don't want them playing with it).

You can read more about this alkyd here.

What is my Personal Preference?

I do perfer to use galkyd lite. I like how hard the painting dries and how quickly it dries. As I don't really have impasto like strokes in my paintings, I like how it evens out my strokes. However, I do not use it...

I share my "painting studio" (aka the third bedroom in my house), with my husband. He, like everyone else, works from home since the pandemic. Then once we added the desk of my arts and craft crazed little girls, my painting room was no longer just mine. As it is a small room, using solvent-free and toxic free mediums are a must. I use Graham's walnut alkyd, dropping just 5 drops of aklyd to 5 drops of walnut oil on my pallet.

Fat over Lean

Quickly, fat over lean means that as you paint, each layer of paint should have more oil in it than the layers below it. It takes six months to a year for most oil paints to completley dry.

Let me explain. In just a few days the paint will be dry to the touch, but it takes forever for the paint to stop its chemical reactions and be fully dry. If layer 2 of a painting has less oil than layer 1, which sits below it, layer 2 will dry faster. This is a problem because as layer 1 dries, it will crack the already dried layer 2 above it.

If using just the premade mediums, no additional oil added, you will want to use less medium as you move through the layers of your painting. So they say.

I have never actually had a painting crack before. I have paintings that I painted over 20 years ago, and still they are just fine without having paid too much attention to the fat over lean rule. The key here, less is more, but being aware of the rule helps. Again, my next post wil cover this idea is great detail.

And there we have it, a bit wordy, but hopefully helpful. Is there anything that I missed? Let me know down in the comments.

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