From Oil to Egg Yolks
Same pigment, different binder.
In a nutshell, most paints are made by mixing dry paint pigment together with a wet binder.
The difference between the type of paints, for example, oil paint, acrylic paint or watercolour is simply due to the different type of binder used.
So the binder could be oil, acrylic polymer or even egg yolk and it’s this – that gives each paint its characteristics…
Pigments traditionally started out as earth or rocks. Some of the oldest pigments are made from coloured earth, like yellow ochre and are called earth colours, they tend to be muted in colour. Different oil colours have been created as new pigments and manufacturing methods have been developed. These modern pigments are brighter and man-made.
Pigments can be divided into three camps:
Inorganic Pigments – Rocks, minerals or metal.
Organic Pigments – Substances that were once part of a living thing, plants, bone or synthetic treatment of plant stuff.
Artificial Pigments – These are often derived from organic pigments that have been chemically altered. They can make a more stable and consistent paint.
A Word of Warning about Artificial Pigments
For those starting painting, I wouldn’t recommend using all man-made pigments as they can ruin a painting more quickly than help it. I always adhere to the practice of starting with the dullest, most natural colours and creeping up on the stronger brighter colours.
This helps you to think more tonally and will pay dividends in the long run. Think small steps.
What are Oil Paints?
Oil paints are made from dry pigments ground together with an oil. Most commonly, cold-pressed linseed oil.
The odour of Oil paint is dependent on the oil used: If the paint is ground in linseed oil, it will smell of linseed oil.
- If the paint is ground in linseed oil, it will smell of linseed oil.
- If the paint is ground in walnut oil, it will smell of walnut oil
- If the paint is ground in poppy oil, it will smell of poppy oil
How do Oil paints dry?
Oil paints dry by oxidation (when the paint has contact with the air)
It’s not the pigment that takes the time to dry, but the oil. Because oil is slow drying, oil paints have a long ‘working time’.
When the oil oxidizes, it forms a solid film that binds the dry pigments together, like baking a cake, the mixture starts smooth, gets ‘cooked’ in the air and dries.
Oil paint can take anywhere between 6 months and a year to fully dry, depending on the thickness of paint used.
What are Acrylic paints?
Acrylic paints consist of pigment suspended in a binder of an acrylic polymer emulsion.
How do Acrylic paints dry?
As water is the vehicle for the acrylic polymer emulsion, acrylic paint’s dry by evaporation.
Because water evaporates quickly, acrylics are fast drying so have a short ‘working time’ (this can vary slightly, depending on the heat and humidity of the environment you’re painting in)
So, which paint will suit you best?
Have a look at the 5 key differences between oils and acrylic paint.
What is Watercolour?
Watercolour paints are pigments held together by a water-soluble binder, along with additives and solvents.
In commercially made watercolor paints, the binder is either natural gum Arabic or synthetic glycol. This is what holds the pigment in suspension. The binder also allows the pigment to adhere to the support (e.g. paper) once it is applied. Additives, such as plasticisers (e.g. glycerin) and humectants (e.g. honey or corn syrup) are mixed in, to alter various characteristics of the watercolors, such as viscosity and durability of the paint. Other additives include extenders and dispersants.
How do Watercolour paints dry?
However, due to the nature and application of watercolours, you’re usually using a lot of water and a support that holds water, so the working time is more than acrylics.
What is Egg Tempera?
Egg tempera is made up of egg yolk, powdered pigment, and distilled water. The egg yolk serves as the binder that holds the pigment together. The addition of water turns the paint into a usable paste-like form. Manufactured egg tempera also includes gums that act as dispersants are like salt, grainy particles that can be milled and crushed to make smaller and smoother.
Pro Tip: To test the quality of a dry pigment, place a small amount in a glass jar, add water, give it a stir and leave for a few days. The solid particles of the dry pigment should float down to the bottom leaving the water clear. If it’s not clear, some form of dye has been added to enhance the colour.
What are Pastels?
Pastels are usually in stick form, similar to chalk.
A pastel stick consists of pure powdered pigment and a binder, such as gum Arabic, gum tragacanth, or methylcellulose. Pastels have a higher pigment concentration than any other artist medium (hence the rich, luminous colors that pastels can achieve). The powdered pigments used in pastels are similar to those found in oil paints.
Pastels can be hard or soft. Soft pastels have more pigment and less binder, so they are easier to smudge and have brighter colours. Hard pastels have less pigment and more binder than soft pastels. Hard pastels can stay relatively sharp, so they are ideal for pastel artwork that requires tight detail.
Some Pigment Colour Pointers:
There are some confusing aspects to the names of pigments, keep these points in mind:
Similar pigments are sold under different trade names.
For example Winsor & Newton’s Winsor Blue and Liquitex’s Phthalo Blue are both based on the same pigment: Phthalocyanine Blue.
Don’t get confused by Hue
The labeling on paints can be really confusing.
‘Hue’ in colour mixing land just means the colour of a paint, i.e. that yellow has an orangey hue to it.
However, in paint labelling, ‘Hue‘ means ‘fake’ or ‘imitation’. So a label that says:
Cadmium Red Hue means that this isn’t a pure pigment made from Cadmium Red. Some of it might be Cadmium Red but it has been mixed with something else to give it a similar colour. This used to be a sign of inferior quality paints but now it’s because some natural pigments are no longer available, not as lightfast or extremely costly. You can read about the 8 key differences between student & artist grade paints here.