Painting & Drawing blog
OIL PAINTING TECHNIQUE: TIPS FOR BEGINNERS
When painting in oils there are some basic rules to learn and to follow to make sure that your painting stands the test of time, but it is well worth the reward because in my opinion oil paints are so much nicer to handle and more pleasing in final appearance than faster-drying acrylic paint. Here you’ll find a step-by-step introduction to the basic techniques.
CHOOSING AND PREPARING YOUR CANVAS
If you visit an art shop you will have the option to buy one of the following options: a traditional chunky stretched canvas in either cotton or linen, a thin canvas board (or ‘canvas panel’) which consists of canvas stuck down to a strong cardboard panel several millimetres thick, or a pad of canvas paper which is a thick paper able imprinted with a canvas-like texture which can take oil paint without warping and crinkling. Canvas paper is suitable for sketching in oils rather than for producing a finished painting to be framed and hung on a wall, although it is an economical way for a beginner to practice. Canvas board may be preferable to a stretched canvas if you like its firmer feel, or if you want to transport it around for any reason as it is a lot less bulky.
Whichever canvas choose make sure it is fully pre-prepared: that is to say that it has been both ‘sized’ and ‘primed’. You’ll find a full explanation of sizing in this article on oil painting materials and why it is so important. Fortunately art shops sell already primed and sized canvases and canvas boards in a very wide range of sizes so you will likely have no need to do it yourself. These will come ready prepared with a nice white surface to paint straight onto. ‘Canvas paper’ pads will also be coated with a priming layer and ready to work onto. The point of sizing is to seal the porous surface of the canvas and prevent the paint with its acidic qualities from penetrating and eventually rotting it, causing the paint to flake off. If you work onto an un-sized canvas then your creation will have a limited lifespan.
Size was traditionally made with rabbit-skin glue (which is still sometimes used) followed by a priming layer of undercoating paint. These days you can still buy separate size and primer if you want to size a canvas yourself, but an easier option is to apply ‘Acrylic Gesso’ which does the job of sizing and priming all in one and is suitable for preparing a canvas for use with either oils or acrylic paint.
Painting onto board
If you prefer an entirely smooth surface and want to paint onto a hard board such as an MDF panel you can certainly do so but you will first need to prepare it using a pot of the Acrylic Gesso mentioned above. Some brands are specifically formulated for painting on wood and sold as ‘Acrylic Panel Gesso’. Others are supposed to be suitable for either canvas, or board. Use as many layers as advised with the instructions on the side.
THINNING YOUR PAINT
So you have purchased your pre-primed canvas and opened your paint tubes, and squeezed some paint out onto your palette ready to mix together. It may be that you like the texture of the paint as it comes out of the tube and are happy to apply it to the canvas as it is. But more likely you will want to thin it a little first. And either way, you are going to need to clean your brushes in something in between colours. Since oil paint isn’t soluble in water, you are going to have to use something else to dilute your paint and clean your brushes.
This is where it all tends to sound very complicated and when you walk into an art store you’ll see a baffling range of products! I’m going to explain what the different types of solution are used for because I think it’s helpful for even a beginner to understand the basics but if you are new to oil painting don’t be too put off by all these rules. They are important to follow if you want your painting to survive for decades and certainly if you plan on selling any paintings. In the shorter term however if you don’t quite get your ‘layer order’ right your paint won’t immediately fall off.
Thinning with spirits
What you will need to use to thin your paint is some form of ‘mineral spirits’. These come in a number of types, and you can read a lot more about them here. To summarize however, I’d advise that to dilute your paint and to clean your brushes you should use ‘Artists’ Mineral Spirits’ which are also known as ‘Artists’ White Spirit’ in some countries, including the UK. This product is an alternative to the traditional (but rather toxic) Turpentine, and is basically the same thing as DIY store White Spirit but with the impurities such as residual Sulfur removed.
Don’t be tempted to use DIY storage white spirit! It may be cheaper but those impurities will destroy your painting, preventing the paint from ever fully drying. For this reason I don’t even recommend cleaning your brushes with it. If Artists’ White Spirit gives you a headache, look for a low-odor version such as ‘Sansador ‘which has been refined even further to remove toxic aromatic compounds.
Thinning with oils
The other types of medium you can use to dilute your paints are various types of oils. Again you can read more about these options on this article . But briefly, the usual oils to use are Linseed Oil, or Poppy Oil for lighter colours as Linseed can be a bit yellowing. Linseed will slow down drying and you may not mind this if you want to continue to manipulate your paint on the canvas for some time. If you want to avoid this effect and actually speed up the drying process you can buying fast-drying linseed, or Windsor and Newton’s ‘Liquin Medium’ which is a fast-drying alkyd medium for oil painting.
Why do you need to dilute your paint with an oil medium as well as mineral spirits? Well, it is okay to use a little spirits to loosen your paint. But if you use too much then your paint will loose all of its shine and viscosity and will also become very thin, preventing you from painting with thicker brushstrokes. Oil paint in a tube is a mixture of a pigment and an oil binder which fixes and sets the pigment as it dries by oxidization. Take away too much of the oil and not only do you lose shine but the paint can’t oxidize and set properly and may eventually flake off.
Therefore to counteract this problem every time you add some Mineral Spirits you add some drops of oil too. Why not use JUST oil to dilute your paint? You can indeed do this, but the more oil you add the shinier your paint will get and you might not like the look of that either. A good balance of spirits and oils will give you the consistency that you want, whilst maintaining the same subtle sheen that the paint has when you squeeze it out of the tube.
If you are a complete beginner and feel baffled by all of these rules!
You might like to try Windsor & Newtons’ ‘Artist’s Painting Medium’ (see above) which is a pre-mixed solution of mineral spirits AND linseed oil. It will ensure your balance of spirits and oils is a reasonable one and will be okay if you are painting with a small number of layers. I’d still recommend applying your first layer with only a bit of Artist’s White Spirit to thin it and then using the Painting Medium in layers above.
APPLYING YOUR PAINT
Always work on a primed surface
We’ve already covered the reasons for this above. I have seen some paintings disastrously ruined by painting onto a non primed surface, causing all the paint to flake off! Make sure to buy a ready-primed canvas.
When thinning your paint with spirits, add some oil to balance them
As described above, if you dilute your paint with a spirit thinner, either because it is too thick or just because you have cleaned your brush in it a lot and then dipped it into your paint repeatedly, make sure you add a drop or two of oil as well. You’ll soon find it easy to get the balance right and to know how much oil to add to get the sheen that you want. If you find that your paint is looking really dull once it is dry then you know you need to be adding more oil. If you’ve added too much oil there isn’t much harm in it this (except on the very bottom layer – read more below) but it might look shinier than you want it to and if you use too high an oil content you may end up with wrinkles in your paint.
Follow the ‘Fat Over Lean’ principle
The well-known ‘Fat Over Lean’ rule simply tells you that it’s not a good idea to make your first layer or two very thickly, and then put thinner, more diluted paint above it. This is because when you apply thicker paint to the bottom layer, the oil content in it will cause it to move and contract as it dries. If you then apply a thinner, diluted layer above it this contraction will cause the thinner paint on top to crack and flake. Additionally the thicker bottom layer with the most oil in it will dry more slowly than the thinner layer above, exacerbating the problem because it will continue to move after the top layer has dried and stopped moving.
Oil paint takes literally decades to dry and whilst it may appear dry to the touch after a few days, but it doesn’t finish the chemical processes of oxidization and become fully stable for many decades. Sometimes people call this rule the ‘Slow Over Fast’ rule and this is really the key. You don’t want the bottom layer to dry more slowly than those above it.
You could therefore rephrase the rule like this: the higher up the layer of paint, the thicker you should apply it and the higher oil content if should contain. Upper layers should have at least the proportion of oil in them that they had when they came out of the tube and more if you’ve applied the paint particularly thickly or if you have added some spirits to it to loosen it. The lower layers should have less oil in them and be applied more thinly than the top layers. In fact it’s advisable to use ONLY spirits to dilute your very first thin layer of paint. Although this may seem at odds with the advice higher up to always balance adding spirits with oils, this bottom layer will absorb oil from the one above it which will prevent the paint from flaking off.
Some historical painters broke the ‘fat over lean’ rule by putting thinner layers of coloured ‘glazes’ (large amounts of oil and a little bit of paint) on the very top to create shimmering effects – for example when painting drapery. This was fine even though this type of layer would be were predominantly oil in their content and therefore remained very flexible and able to survive the movement of the layers below. Stand Oil was traditionally used for this purpose, which is thickened Linseed Oil.
Here’s a useful video describing the ‘fat over lean’ rule.
For thick ‘impasto’ painting
Now of course, you may not want to work in lots of layers. You might want to work with only one layer on top of your sized and primed background, which is fine. If that means that you are applying very thick paint however, make sure to add some ‘Impasto Medium’ which will stiffen your paint but is specially formulated to prevent it from cracking in unstable atmospheric conditions. Impasto medium is designed to make the paint stand in thick peaks like icing or frosting and comes in a tube or a tub. It’s a modern invention and unlike the traditional Stand Oil allows for much thicker top paint layer whilst preserving the appearance of the brushstrokes and the regular sheen on the paint, whereas Stand Oil flattens your strokes and results in a very oily look.
Your base layer
As I have mentioned, a pre-primed canvas will be brilliant white in colour so you may want to begin your painting by either first blocking in large areas of colour or by applying a base layer of one particular colour to the whole canvas. The major advantage of this is that when faced with a bright, white canvas, you may find it hard to judge the tones you want to put down – whereas if you start off with a canvas that’s painting in a mid-tone (say a brown, or bluey-grey) these tones become easier to discern. This is particularly the case if you are painting from observation.
Historically, painters would not have started off with a white layer but rather a darker and richer tone to bring a warmth to shadowed areas as you can see in this beautiful unfinished painting by Thomas Gainsborough. In the modern (more abstract) era a white background has became popular as it gives the paint on top the greatest vibrancy.
If you want to apply a base layer of coloured paint then follow the ‘fat over lean’ rule above and apply a reasonably thin layer of paint, using a stiff and fairly dry brush to spread it well over the canvas. Another reason for applying a first layer thinly is that you don’t want to have ‘ridges’ in the paint when you come to begin your painting. If this happens, you can sand any ridges down with some fine-grade sandpaper once it’s dry. It might be worth adding a drop or two of ‘drying oil’ to your first layer (but not TOO much – you don’t want your bottom layer too oily, as we have discussed above). You’ll find that the first layer of paint takes the longest time to dry, and each subsequent layer will dry more and more quickly. This is because when applying later layers the oil in them will sink down and be absorbed by layers below.
A NOTE ABOUT WHITE PAINT IN YOUR FIRST LAYER
The main concern here is drying time. The first layer of paint takes the longest to dry, as I have just mentioned. Some types of white paint can take longer to dry than any other colour, so a white underlayer could take a good week to dry. Even if you’ve chosen a darker colour for your base layer, chances are it will have a fair bit of white in it. Generally for white paint these days we use either Titanium White and Zinc White. Titanium White is a nice, opaque white, but is extremely slow to dry. Zinc White dries a lot faster, but can cause cracking so do not use a lot of it in your under-layer. However it’s now possible to buy a faster drying ‘Underpainting’ white paint. Windsor & Newton and Daler-Rowney both make an ‘Underpainting White’ which is a mix of Titanium and Zinc pigments, with added texture to help the later layers of paint adhere. It has a faster drying time than using Titanium alone but won’t cause your upper layers of paint to crack.
USING YOUR PALETTE EFFICIENTLY
When putting out my paint on the palette I like to group my colours together (reds and yellows, greens, blues, and browns) and to keep these groups in the same places on my palette each time. This sounds a little over the top perhaps, but you’ll find that if you do this you’ll soon learn by instinct which part of your palette to look for the colour that you want and won’t have to search for the right colour constantly. It really saves a lot of time when you have many colours all over your palette! In the middle I put white because I will so often add a bit of white to any colour that I mix.
At the end of a painting session to keep the colours you have squeezed out or mixed up moist and workable, cover them with Clingfilm (plastic wrap) to slow the speed with which they will dry out. You can find more tips on how to reduce waste in this article on oil painting hacks.
As mentioned above it takes years for oil paint to completely dry but it will be touch-dry and suitable for painting over with the next layer after a day or two. Thicker coats of paint will dry much more slowly than thinner ones. However even if applied appropriately thinly the very first layer takes the longest to dry, whilst the later layers will dry with increasing speed as the oil content soaks into the layers below. You will also notice that different colours take varying amounts of time to dry. Lighter colours always seem to me to take much longer than colours with darker pigments in them. This is another reason to apply a mid-tone, slightly darker colour for your first layer.
Be aware that as mentioned above, Titanium White takes a really long time to dry. I use Titanium for upper layers, but for a first layer I will use Zinc White – which dries a lot faster – mixed with some drops of a drying oil, or an Underpainting White. To speed up the drying of all your layers you can use Drying Linseed Oil. This is good for mixing with most paint colours, although it can be a bit yellowing so may not be suitable for very light shades. Instead for lighter hues you may prefer to use Drying Poppy Oil. Windsor & Newton’s ‘Liquin’ medium halves the typical drying time and claims not to have a yellowing effect – although this has been disputed) and is available in several different thicknesses, plus two Impasto mediums.
CONSERVING YOUR PAINTING
We have covered in depth the need to paint onto a properly prepared ground and to get a good balance between spirits and oils in your paint layers. However as important as these are to the long-term conservation of your painting, the environmental conditions in which you store and display your painting are even more critical. Keeping a painting in damp conditions or vary variable temperatures can be disastrous and will cause flaking in a relatively short time. You can read more on looking after an oil painting in this conservation and framing guide.