An Introduction to oil paint

by Cass Art

What is it?

Oil paint is a type of slow drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed, safflower or poppy oil. The viscosity of the paint can sometimes be modified by the addition of solvents or resins. It has been about since around the 12th century. The reason oil paint takes so long to dry is because when exposed to air, oils do not undergo the same evaporative process as water does. It polymerizes into a dry semisolid. This rate of process can be very slow depending on the oil.

The advantages of the slow drying quality of oil paint is that an artist can develop a painting gradually as they don’t have to worry about the drying time and helps with the lack of colour shift due to the prolonged period. Linseed oil has been the most popular drying oil in the whole of the oil painting history. It dries comparably fast, and a layer on a canvas by this oil has good endurance. The only weak point is yellowing. The film tends to change its colour into yellow or dark. Therefore almost painters avoid this oil for bright colours like white or yellow.


Pigment

The colour of the paint derives from small particles of coloured pigments mixed with a carrier. It is the powder that makes up the colour of a paint. Manufacturers give their colours different trade names, so if you're buying a new brand and are unsure whether you've got the right colour, you can check by looking at on the tube label what pigment(s) that colour is made from. Pigments also vary in price. Paints are usually classified into series, indicated by a number on the tube, which cost increasingly more as the pigment becomes more expensive. So, for example, in Winsor & Newton oils, bright red is series one, cadmium red is series four, and carmine is series 6.

There are two types of pigments – Organic and Inorganic. Organic resulting from something that has lived: plants, animals. Inorganic resulting from something that has not lived: rocks, metals. One type is not necessarily better than the other, what distinguishes them is not the quality, but their ease of sourcing , ease of grind into their binders and characteristics (drying time, transparency and tinting strengths) to make paint will all contribute to their price. 

Oil Binders

Linseed oil has been the most popular drying oil whole of the oil painting history. It dries slowly, and a layer on a canvas by this oil has good endurance. The only weak point is yellowing. The film tends to change its colour into yellow or dark. Therefore almost painters avoid this oil for bright colours like white or yellow.

Poppy oil or Poppy seed oil is becoming less popular as a binder nowadays due to its cost. The advantage of this oil is that a layer by poppy doesn't change its colour easily different from linseed oil. Therefore many painters used poppy since Impressionists (they painted thick layers of bright colour) instead of linseed. But Poppy oil dries very slowly and a layer by poppy is inferior in endurance.

Safflower oil is similar to Poppy oil in that it is has a much slower drying time than linseed oil. The film by safflower oil hardly change its colour into dark. Recently this oil is frequently used as binder of tube oil paint instead of poppy because its cost is cheaper than poppy oil.

The use of Walnut oil in paint can be traced back even further than that of linseed. Walnut oil was preferred as a binder for whites because it has the reputation for yellowing slightly less than linseed, and so paler and cooler colours bound with it underwent less change in drying. The film of dry walnut-bound paint is not quite as strong as that bound with linseed, but it is stronger than that of poppy or Safflower oil.


Artist Quality v Student Quality

Artist’s quality oil paints are made of the purest and highest-quality ingredients such as the greater the pigment content and being devoid of “fillers or extenders” making them the highest quality paint you can get. Their prices are divided up in series, the higher the series the more expensive the pigment leads to the more expensive tube of paint. Artist’s quality have a much greater spectrum to choose from also.

Student quality oil paints usually has more “filler” in the tube, so while it may appear to be thick and buttery, there’s less pigment in there. This is the main difference between the two qualities of paint. Although because of this it makes the paint more affordable which is perfect for beginners trying to familiarise themselves with the medium. But this does means you need more paint to get the same tint or coverage that you’d get with Artist grade. Student paint also tends to use cheaper lookalike pigments that may not have the same strength or lightfastness as their artist-grade counterparts. Student paint may not mix the same as artist quality, so if you’re following a colour mixing recipe (two parts titanium white to one part cadmium red light, or whatever), your mixture may not turn out as expected.

 

In short -  

 Artist Grade

-Highly pigmented means high quality

-Vibrant colours due to this.

-Larger spectrum of colours

-Better Lightfastness and tinting qualities.

Artists range of paints available, Cass Art, Winsor and NewtonMichael HardingOld HollandSchmincke Mussini


Student Grade

-Less expensive (allows you to experiment more)

-No series means one price for every colour.

-Great practice for beginners.

Student oil paints at Cass Art: Winton, Georgian, Pebeo, 


Oil Mediums

An oil medium is a substance added to paint in order to alter the way the colour behaves and in some cases appears. There are a number of reasons why you might use a medium, including to alter sheen, drying time, texture or transparency. Mediums are available to suit oil, acrylic and watercolour, although they are not compatible across media. Here is a summary of all the different varieties of medium available for oil paint.

WHY USE MEDIUMS IN OIL PAINTING AND?

Mediums are used to adapt the consistency, drying time and finish of your painting. You can achieve a variety of different sheens and either extend or shorten the drying time of the paint, depending on which you use. You can mix them directly with the paint on your palette, or dip your brush into them as you would with water.


DIFFERENT TYPES OF OIL MEDIUMS

TURPENTINE

Turpentine is technically a solvent, and one of the more traditional ones that painters use. It speeds up the drying time as it dilutes the paint and evaporates off of it (the equivalent of water for acrylic paint, if you like.) The Winsor & Newton Distilled Turpentine is great for thinning your oil paint as well as cleaning your brushes. It's the multi-tasking tool needed in every oil painter's studio.When painting in layers, you should use turpentine for your basecoat or first layer of paint, as you should always apply your fast-drying layers first. 

LINSEED OIL

Generally linseed oil is regarded as the most popular drying oil since around the 1400s mainly due to it’s versatility which makes blending and glazing easy. Linseed oil, like all drying oils, has a chemical reaction with oxygen which causes it to polmerise, encasing the pigment and helping to maintain colour vibrancy for years. 2 of the most popular kinds of linseed oil are Cold Pressed and Refined.

LIQUIN

The Winsor & Newton Liquin Original Medium is one of the best-selling mediums at Cass Art. It speeds up drying time, which we all know can be a bonus, and halving the drying time of your painting. It also brings a silky consistency to your paint, giving the surface a glossy finish. Another advantage is that it doesn’t affect the colours of your paint.

 

STAND OIL 

The Winsor & Newton Linseed Staind Oil is thick with the consistency of honey. It’s extracted from the Linseed too, but is left to stand and thicken. You can therefore use less of it because it’s more concentrated. It’s a translucent medium which makes it good for glazes, and it levels out your brush strokes to leave a glossy sheen. Mix it with Turpentine to make your own medium. A small quantity of Stand Oil mixed with Turpentine will make a slow-drying medium, one that will dry slightly quicker than when you use Linseed Oil on its own. 

Water Mixable Oils

The difference between this and regular oil paint is the binder. The two different types of binder used are modified Linseed oil or Safflower oil, which are simply a water mixable oil. It is Ideal for those who work at home or those who are more sensitive to harmful and abrasive solvents, water mixable oil colour allows you to enjoy the rich and luscious nature of oil colour whilst being able to wash brushes and thin colour with water. All water mixable oil colour ranges can be mixed with one another. Winsor and Newton Artisan also have their own range of water mixable thinners and mediums. Please note that while these colours are water-mixable, they are still oil based, and so supports should still be sized and primed properly to prevent the oil from rotting the support.

Water-Mixable oils dry in two stages: the water evaporates and then what is left is similar to conventional oils and dries by oxidation at a similar rate to conventional oils. Just like conventional oils you still need to remember the fat over lean rule, you still need to let the painting dry completely before you varnish for protection, you cannot mix with acrylic but like regular oil pain can be painted over acrylic. You can mix with regular oi paint too, you just lose the ability to clean up without a solvent. The two brands we stock of these are: Winsor and Newton Artisan Water-Mixable oils (pictured above) and Cobra Water-Mixable oils.


Feeling Inspired?

Now you've got an overview of all things oil paint, read out 6 top tips for getting started here.

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