Linseed oil makes strong flexible paint films. We’ve all seen paintings hundreds of years old made from colorants bound in linseed oil.  Since WWII improvements in refining processes, finally, assures flax seeds are separated from weed seeds.  Weed seeds are similar in size but produce a non-drying oil. When mixed with linseed oil, weed seed oil inhibits drying.

Today’s linseed oil is purer and naturally dries more quickly.  Also, contemporary artists’ grade oil colors have high(maybe too high) pigment-to-oil ratios. Adding more binder is a plus. For direct painting styles, especially using knives, most artists’ colors do not require much modification.

Using only linseed oil to thin colors makes oilier (fatter) paint layers. Historically, painters made a painting medium from oil and solvent to increase paint flow, especially for glazing. The fatter the layers, the more they wrinkle.  As an illustration, a studio assistant called to say the painter’s recent large format canvases had developed significant wrinkling. I asked about which colors and mediums he had used. And, yes, the painter was making very shallow pours on the canvas using thinned out alkyd resin painting medium. The “problem” was how could he replicate the wrinkling - he loved the surface.  

Curious, I called his art supply dealer to check inventory for gallon cans. Seems the painter had received a gallon of linseed oil instead of his usual medium. While seemingly an easy fix for me - all I had to do was ship more linseed oil, I worried. I advised the painter to be patient and consider these painting experimental until he sees the real effect of adding that much slow drying binder. The final effect was stunning.

Use good quality refined linseed oil from an art materials dealer.

Sunshine will take care of most of the natural yellowing.

Avoid cold pressed linseed oil unless you are exploring Old Masters’ techniques.

In general, consider using a small measure of solvent more like a condiment than a component of an oil painting system unless you have extreme allergies or compromised immune system. A little solvent enhances your control over the viscosity of oil paints.

Adding a small measure of solvent means you can add less oil to moderate the viscosity, especially for glazing. Alkyd resin-based painting mediums contain solvent.  Adding some can replace the solvent condiment.  But you will need a odorless mineral spirits (OMS) to reduce the stickiness of alkyd resin for clean up.

Adding solvent does NOT speed up drying.

How Do Your Make The Right Measure?

Dip your brush into OMS before mixing your paints.  Begin with, literally, just a few drops and adjust the oil/solvent ratio according to how the mixture feels.

        •Linseed oil can no longer bind when extended beyond 1/3 oil to 2/3 with OMS.  

        •If extending with turps, 1/2 to ½ max.

What kind of solvent? 100% ODORLESS MINERAL SPIRITS (OMS) is odorless.

Most everything artists need to know is on the product labels:        

“Petroleum Distillates” are hydrocarbon solvents produced from crude oil, including mineral spirits, kerosene, white spirits, naphtha, Stoddard solvent. Artists quality OMS is strong enough to defat oil and not strong enough to dissolve or extend dammar varnish.

There are some interesting urban legends about OMS being more dangerous because you can’t smell it.

Not true. The aromatic components (ones you smell) have been removed and a lot of the solvent power has been removed as well.  “Mineral Spirits” (MS) is a stronger solvent than OMS with a higher aromatic component. You can smell how strong it is.  Also known as “White Spirits,” MS should be carefully controlled. Buy in small measure, use sparingly.

Unless you are a painter who wants to crack the paint film, scrape or shatter, OMS should offer enough solvent power. Just change the air in your studio at least once a day and you’ll have less solvent exposure than spending a half hour in a nail salon!





Turpentine is a generic name for distillations from tree resins. Its name comes from the Greek for a Mediterranean tree, “terebinth.”

By the second millennium BCE, distillation of all manner of spirits was common. Turpentine was the traditional oil painting solvent simply because nothing better was available for clean up until mid-20th century when petroleum distillates, MS and OMS become widely available. “Turps” usually refers to inferior quality turpentine or white spirits.

Now, when used only a condiment, turpentine and other solvents can compliment a painting system.  Turpentine can “bite” a dry paint film, open a layer up for glazing or overpainting and make a unique drip mark. If you simply must try it, buy a small amount of water clear (glass container), double distilled turpentine from a reliable brand. Cheap turps from the hardware store contains as much as 20% impurities that yellow the solvent and any expensive oils paints you mix with it.

Be suspicious of cheap OMS, too. If you can smell it, it is not odorless regardless of what’s on the label.

Consider OMS as the solvent you go to first to increase fluidity and speed clean up.  Consider turpentine the strongest solvent you’ll need.  The KB value of turpentine is required to dissolve dammar resin and extend resin varnishes.

If working without solvents is the key to your continued working in the painting media of your choice, you can --

            •wipe surfaces rag clean and live with a slight haze.

            •clean brushes with mild soap.

            •use mineral oil (baby oil) to condition brushes. Wash again before using with oil paints.

            •during the painting process, consider lightly sanding shiny surfaces and dust off before adding a new layer.