Using Colours - mixing and characteristics
Placing colours on the pallette
When you decide which colours to use in the painting you are planning to do, you can place an amount from each colour from the tube onto the pallette. Always try to keep the same order of how you place the colours, usually using the order of the colour wheel. I usually place the colours in the order starting from reds on the left hand side, yellows and blues on the right hand side. I place White on the right hand side and browns just after the reds. Always place the colours on the upper part of the pallette and leave a lot of space for mixing colours.
Diluting colours
Most of the time we will need to dilute colours since they are usually too thick to use directly from the tube. You thin the colours by using one of the several media that are available. However for oil colours the most common diluents used are pure gum terpentine, odourless mineral spirits and refined linseed oil.
Since you want the underpainting to dry very quickly the best to use are odourless spirits or pure gum terpentine. I prefer the former due to lack of odour. You can dilute the paints either by dipping the brush in the mdium before picking the colours obviously adding amount of mineral spirit depending on what you want to achieve. The more diluent you add the thinner the paint and the more it dries quickly. This is good to do a wash for the underpainting. You can thin the colour especially white by adding drops of diluent onto it while mixing with painting knife until the paint has a consistency like a toothpaste.
For the next layer of paint I will dilute using a mix of 1:4 linseed oil with mineral spirit.
To decrease the drying time it is also wise to use liquin which decreases drying to almost 1/3 of the normal time.
In the case of acrylics usually you dilute with water or else one of the several media available that usually are used to increase drying time since acrylics dry very quickly especially in hot and dry conditions.
Drying Times
Different oil colours have different drying times. This is because oil colours do not dry by evaporation but by oxidation. Here are some examples:
Fast drying times (1 - 2 days) cobalt blue, Prussian blue, Raw sienna, umbers, Flake white
Medium drying times (5 days) permanent alizarin, cadmiums, ultramarine blue, ochres, burnt sienna, titanium white, zinc white
Long drying time (> 5 days) acrylamides, alizarin crimson, quinacridones
Use of colour in landscape painting
In order to create the illusion of distance as well as other characteristics such as time of the day or seasonal variations one has to know which colours to use in a landscape. As a general rule, very cool colours will recede in distance while warm colours appear to be at the foreground. However there are different blues, reds and yellows available that can in themselves be warm or cool. Here are some examples:
- Cobalt and cerulean blues are cool blues very good for skies and distant objects especially when mixed with white. Add crimson as you move closer (turning purple) and a touch of raw sienna to change it to grey.
- Ultramarine blue is a warmer blue and can be used for objects that are closer
- Alizarin crimson is a cool red and so it is ideal for backrounds, to darken mountains and other objects as they come closer and to create shadows in the clouds or purplish colours in the skies. When mixing will alizarin crimson be cautious as the colour is very intense and you will only need to use very small amounts
- Cad red, vermillion are warm reds with cadmiums being the warmer, so usually these are used for nearby objects
- Cadmium yellow or orange are warm while lemon yellow is a cool colour. For background yellows or greens one can use raw sienna which can look yellow especially when mixed with white
- Vermillion is a pure and very intense green but rarely used on its own due to its strong and artificial looking colour. You can use touches of vermillion mixed with other colours such as raw sienna to give a green tint.
- Burnt umber can be used for foreground and the same for burnt sienna. Burnt umber creates an interesting green when mixed with veridian
- Always try to darken a colour by using the opposite colour (complementary) on the colour wheel.
- Indian yellow or Australian red gold forms a bright yellow (golden) when mixed with white.
