Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by Joelle Gandara
The Art of Rocks
Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil. It has been used in Europe since the 12th century but was only widely adopted as an artistic medium in the 15th century. The modern applications are as finish and protection for wood in buildings and exposed metal structures. But how is it made?
The Basics of Creating Modern Oil Paints
Start by having the proper materials:
∑ A binder- walnut or linseed oil
∑ A grind slab- a sheet of glass or marble to mix the oil paint on
∑ Pigments- either bought or self-ground
∑ A palette knife- a metal utensil used for mixing paints and applying paint to canvas
∑ A muller- usually made of glass, used for grinding the pigment evenly into the binder
A container Ė air tight jars or paint tubes to hold excess
1. Place a small amount of pigment and a small amount of binder on the slab. Different pigments will need different amounts of oil so start with small amounts.
2. Slowly mix binder and pigments together with a palette knife (you may need to add more pigment or linseed oil to improve the consistency)
3. Push the mixture to one side, leaving about a teaspoon in the middle. Use the muller to grind this small amount in small circular motions avoiding excess pressure. Move the finished paint to one side. Use this method for the rest of the mixture.
4. You want to mix until you have a soft, buttery consistency. Move to your container.
There are kits you can buy with the pigments and oil needed to mix your own oil paints. One example of the kit is The Earth Oil Paint Kit offered by the Natural Earth Paint.
Or this kit, by Natural Pigments.
Linseed oil: The most common oil used with many varieties based on its purity. Has a tendency to yellow with age.
Stand oil: highly weather resistant and dries glossy
Poppy oil: dries very slowly and not as hard as linseed oil
Walnut oil: fast drying
Sunflower oil: yellows less than linseed oil
Solvents and resins
Solvents are added to oil paints to temporarily change the way they work and evaporate evenly and completely. Others are also used to dissolve resins, making mediums, cleaning up, and for cleaning brushes.
Turpentine: a tree resin with the quality of drying fast but releases harmful vapors and can be absorbed through the skin.
Mineral spirits: has a petroleum base with a moderate evaporation rate. It releases harmful vapors but is said not to be absorbed through the skin. Take precautions when using.
Odorless mineral spirits: mineral spirits that have had some of the harmful vapors removed.
Alkyd-based mediums: has a faster drying time.
added to increase the gloss, reduce the color, reduce the drying time, and adds
To get the colors artists wanted in older times, before you could buy kits with premade pigments, they would grind things of similar color to get the right pigment. Charred bones, claystone, and iron oxide were commonly used as well as other materials such as semi-precious rocks. Today they can be used for coloring paint, ink, plastic, fabric, cosmetics, food, and more.
Certain colors are known to be created through certain minerals.
can be created through tinted clay that contains mineral oxides, which will
create a range of ocher from yellows, golds, and reds.
can be made with limonite clay, an iron ore, to get a rich, earthy red.
Umber can be made with clay that contains iron and manganese oxides creating darker colors than sienna or ochers with a range from cream to brown depending on the ratio of iron and manganese.
Other colors used to derive from precious stones but are now made synthetically.
Ultramarine used to be made with lapis lazuli but is now made by heating a
combination of soda (sodium carbonate), clay, and sulfur to make the deep blues
and violets. The pigment on the left is a natural ultramarine while the pigment
on the right is synthetic.
Spinel, a gemstone with a composition of magnesium and aluminum that are created by volcanos, has also been used to create vibrant colors with spark that comes in a variety of colors. This stone is rarer but less precious and easier to grind than the corundum, rubies and sapphires.
Spinel, crystalline and cut. (Photo: Wimon Manorotkul)
The Viking Way
took a step by step process of how to make your own Viking Age paint. His
process is about how to choose a rock, grind it down, and add the oil.
rock with a color that you like and that is easily crushed.
Wash the rock to remove any dirt or mud. In a container break into small pieces then sort them into piles of light, dark, and every shade in-between. He but advises that a granite mortar and pestle should work fine.
Using circular motions grind and crush the rocks to a smooth dust. At this point he uses a ball peen hammer in his armoring form.
color is not what he wanted he burns the stone, which may lighten or darken.
Some may be toxic, take precautions.
uses a metal mortar and pestle to grind the dust even more using circular
motions without twisting. It is fine enough when you put a pinch in the palm of
your hand and it can be completely blow away without leaving residue.
thickened linseed oil to the powder and keep grinding. When itís of the
consistency of honey, very smooth and easily sticks to a brush, it is usable
paint. At this point if you are happy with the color start painting, if youíre
not happy with the color go to the next step.
If youíre unhappy with the color you can always add more pigments to change the color, as well as adding more oil to keep it at a honey like consistency. Start painting!
You can read his exact process here:
As with most things, oil paints have their dangers. Fist would be the pigments used in the paints. Certain colors can contain toxins such as lead, mercury, cobalt, arsenic, chromium, cadmium, and barium. When these colors touch bare skin the toxins can be absorbed into your blood stream. Other synthetic colors are petroleum-based or contain preservatives such as formaldehyde.
such as Turpentine, paint thinners, and mineral spirits, and varnish are also
toxic to breathe the fumes in. Long-term exposure can lead to cancer and damage
to the liver, kidney and central nervous system.
Using proper protective gear will eliminate the risk of chronic diseases from heavy metal toxins. Wearing latex gloves, face mask, and safety goggles.
Paint brushes can contain hazardous materials for up to five years.
Another danger is that all of the cadmium pigments, a family of yellows,
oranges, and reds, contain the element cadmium. It is more commonly known by its
use in rechargeable nickel-cadmium batteries. Cadmium is an extremely toxic
metal with a low permissible exposure limit. Artists are under threat of
ingesting dangerous amounts, particularly when it is used in a dry form or when
mixing their own paints.
For more information about natural, non-toxic paints you can make yourself or on cleaning up after painting read:
If you would like to read more about how to make other kinds of paints one place to look is at this webside:
How to make Egg Tempura:
History of many forms of arts: