When I started out oil painting I was intrigued by the collection of different oil painting mediums on the art store shelves: I had no idea what they were for and, in 2003, there wasn't much literature available online. It took a few years before I decided to try some out and even longer for me learn to use them properly.
For this blog post I wanted to focus on how to use the most popular medium, i.e. Liquin, in your own oil paintings. Nowadays there's tons of information available online, but I think there's always room for a different viewpoint, especially when it comes from first-hand experience. In particular I want to help new artists make that first step and prevent some easy-to-make mistakes.
I originally had a simple article in mind but the more I wrote, the more I realized that everyone reading this might have different levels of experience. Since I wanted this article to be understandable by beginners, I'm going to start at the very beginning.
But before I go any further—for those looking to find out how to make your own Liquin or other type of alkyd resin: to the best of my knowledge it's made using a manufacturing process that requires access to industrial-grade chemicals and equipment—not the kind of thing you can mix up in a bucket in the shed. See here for more information: https://polymerdatabase.com/polymer%20classes/Alkyd%20Resin.html
What is Oil Paint?
Basically, artist's oil paint consists of a dry pigment (usually a powder) mixed with a drying oil. In the mixing process, the pigment is ground down to a very fine level. The oil binds the particles of pigment together and it subsequently turns to a hard film by reacting with oxygen in the air.
Some oil paints also contain other ingredients in small quantities (for example, chemicals which may retard or speed up drying times), but these are almost never listed on the tubes.
Depending on the brand and the type of pigment, oil paints have different proportions of pigment and oil. Paints with a greater proportion of pigment are more concentrated and are usually more desirable since an artist can only dilute them, not increase their concentration. In fact, some of the more expensive paints are so concentrated that they must be mixed with something to make them easier to use.
That something is called a medium and it generally has one or more of the following effects on the paint:
- changes the consistency
- makes it go further
- alters the drying properties
- makes it more durable
- make it more flexible
What is Medium Made From?
A medium can be made from anything that both dries and mixes with oil. Some popular examples are:
- linseed oil + solvent
- stand oil + solvent
- alkyd resin + solvent
Where the amount of solvent could be anything from zero to double the amount of oil, or more.
It has been proven that increasing the proportion of oil/resin in each new paint layer extends the longevity of the paint film and helps it resist cracking.
This is called the "fat over lean" rule, and is one of the few true rules in painting.
There are two easy ways to increase the proportion of oil/resin: either use the same amount of medium but make it with less solvent, or (in the case of undiluted mediums) use more medium.
For more information on "fat over lean" you can refer to Ralph Mayer's book "The Artist's Handbook of Materials and Techniques" which gives an easy-to-understand explanation of the materials science involved.
What is Liquin?
Liquin is the brand name of a type of alkyd resin sold by Winsor and Newton. It is used as an oil painting medium.
Compared to linseed oil, it's "stickier", dries faster, and remains more flexible with age. You can read more about the chemistry of alkyd resins here: https://en.wikipedia.org/wiki/Alkyd
Alkyd resins perform like linseed oil—they dry by reacting with oxygen to create a hard film—but have a different molecular structure which renders them tougher and more flexible than oil when dry.
Naturally, bottles of Liquin say almost none of this on the label. Nor are the contents explicitly listed except to note that it contains petroleum distillates—in this case just enough solvent to make the contents easier to get out of the bottle.
Because of this, Liquin carries an ACMI health warning label of "CL" or cautionary labeling.
Why Would You Want to Use Liquin?
For most artists, the biggest benefit of adding Liquin to your oil paint is that it makes it dry faster. That enables you to work in layers more easily since you should, ideally, wait for each layer to dry before painting on top of it. In my experience, it also means most paintings will be dry enough to ship out of the studio door within a few weeks.
The other main benefit is that it only modifies the paint viscosity by a small amount: it keeps the paint thicker and stickier than linseed oil will.
The label claims that it improves gloss, but I don't know of any artists who actually use Liquin for that reason. Any gloss enhancement is fairly small and usually not noticeable under a layer of varnish.
How to Use It
It's important to use Liquin in small amounts. Just a drop or so for every inch you squirt out of a standard 37ml tube of paint. You can add an extra drop of Liquin to each subsequent layer.
If you use Liquin (or any other type of alkyd resin), make sure to use it in all of the layers in your painting. You want to avoid putting fast drying paint over slow drying paint and it's the best way to ensure the paint film will remain strong over time.
Liquin is not suitable for use as an oil painting varnish—it tends to turn yellow and is not removable—but it can be mixed with an equal amount of oil and used in a very thin layer for oiling out.
All Oil Mediums Can be Intermixed
Liquin can be mixed with all painting oils like linseed oil, walnut oil, etc. and also with every other type of oil medium including driers, dammar varnish and all types of solvents like turpentine, odorless mineral spirits, and d-limonene.
Liquin shouldn't be used with water-mixable oil paints if you want them to remain water mixable. Use a special water-mixable medium instead.
I paint with my own 50:50 mixture of Liquin and linseed oil, with d-limonene added as a solvent in the first layers. Read more about it here: https://portraitsbysimonbland.com/blog/how-can-i-make-my-own-oil-painting-mediums/
What are the Downsides to Using Liquin?
First of all, you're going to lose the aroma of linseed oil and replace it with the smell of paint. It's not a particularly pleasant smell and you need to have ventilation while using it.
Secondly, you're introducing another source of petroleum distillate fumes into your studio in a time when oil painters are trying to find ways to minimize their exposure to toxic products.
Finally, I've noticed that if you use too much of it in your paint you may find it difficult to get any painting varnish to stick—the varnish will tend to bead.
What are the Alternatives to Liquin
Just about every oil paint manufacturer sells an alkyd resin medium.
In the US, you are most likely to come across the Gamblin products. Their Galkyd mediums are similar to Liquin and mediums such as Neo Meglip also have an alkyd resin base.
If you are serious about reducing fumes in your studio, I highly recommend their solvent-free alkyd gel which comes in a tube. This product is somewhat thicker than Liquin and I find it helps to enhance paint textures, although I often end up mixing it with solvent to make it more usable.