More oil painting bit and pieces that are needed or are additional/alternative materials or equipment.
Oil mediums are usually mixed with oil paint to modify the way it handles, thicker, thinner etc. Most of the oils used as mediums for oil painting are known as drying oils and each has different drying times and properties. The medium is mixed with oil paint to a: modify the way the paint handles straight from the tube (drying time or thicker/thinner) and b: alter the character of the paint from what you get straight from a paint tube (gloss, matt, transparent or opaque).
Refined linseed oil is the most commonly used medium, but it's worth giving others a try, even as a beginner, as they all have slightly different properties.
Many artists don't use any medium, apart from maybe a small amount of Refined Linseed Oil thereby allowing the paint to become more workable, as some paints are thicker straight from the tube. Oil painting mediums is really a matter of personal taste, experience in their use and is not a requirement.
Linseed oil is used as binder in today's oil paints. It is also used to thicken the consistency of the oil paint. Linseed oil not only adds gloss and transparency but it dries thoroughly and forms a strong paint film. Linseed oil dries slowly, therefore the paint remains in a workable state allowing further work to be carried out for some time. It however also dries thoroughly, so makes it ideal for under painting or the initial layers. When linseed oil ages, it does tend to yellow. Many artists avoid using linseed oil with lighter colours.
Below are further linseed oil based products.
Linseed Oil - Cold Pressed:
This oil is made by extracting (using pressure and not heat) the oil from raw flaxseed and creates a pure linseed oil, considered the best quality and therefore more expensive. It dries slightly faster than refined linseed oil. Along with being used as a medium to thin oil paints, it can be used as a binder, heighten gloss & transparency plus reduce the visibility of brush strokes.
Refined Linseed Oil also called Steam Pressed Linseed Oil:
Unlike cold presses, Refined Linseed oil is steam heated and then pressed, which yields more oil, making refined linseed oil less expensive. Refined linseed oil is an all-purpose, pale to light yellow oil which dries within three to five days and is used as a binder in oil paints and artists use it for thinning oil paint and transparency.
Sun Thickened Linseed Oil:
Sun thickened linseed oil is a thick bodied medium with a honey like consistency. It's produced using the heat of the sun when an equal amount of linseed oil and water are mixed together in a container and left for a few weeks, or longer, in the sun where the linseed oil and water eventually separate.
Sun thickened linseed oil isn't used as a binder in oil paints but does improve flow and increases gloss plus it has less of a tendency to yellow compared to others and speeds drying.
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Stand oil is another thick medium, similar to sun thickened linseed oil. The Linseed oil is heated at a high steady temperature, in an air tight container, which results in a very thick honey like consistency.
Stand oil is useful as a glazing medium when mixed with a diluted or solvent such as turpentine. It helps improve the flow of the paint and has resistance to yellowing but is slow drying and produces a strong paint film without any brush marks.
Other Oils and mediums:
Because linseed oil has a tendency to yellow as it ages, other oils have come onto the market. Amongst these oils are poppy seed and safflower oil.
Being a very pale oil, it is often used with whites, blues and pale colour, it's more transparent and is less likely to yellow than linseed oil. Poppyseed oil does take longer to dry compared with linseed oil - five to seven days, which makes it ideal for working wet on wet. The downside of the slow drying is when working wet on dry or applying paint thickly, as the paint will be liable to cracking when it finally dries, therefore its best avoided in the lower layers of an oil painting.
It gives oil paint a consistency similar to soft butter. Poppy seeds naturally contain about 50 per cent oil.
This oil, made from safflower seeds, is similar to poppy seed oil in that both are suitable when used with whites and light colours but does dry a bit faster. It's less inclined to yellow when compared to linseed oil.
A thin pale yellow-brown oil that helps make paint more fluid, yellows less when compared to linseed oil, again good when using pale colours and dries in four to five days. It has a distinctive small, is expensive and needs to be stored properly.
A much used oil painting medium. It's an alkyd medium produced by treating a natural oil with alcohol and an acid. This produces a product that greatly speeds up the drying time (up to half) of oil paints and is one of the main reasons for its use.
The painting still needs to be fully dry before varnishing - which can be six to twelve months, so it doesn't save time with that. If you need to add some protective surface before then, Artists Retouching Varnish can be used.