From Watercolours to Oils in a month!

Updated: May 8

Oils for Watercolourists

In this second article I’d like to look at how you can transfer from watercolours to oils. Let’s start with the good news; if you can paint well in watercolour then you already have most of the skills you need for classical oil painting.

Despite this, many watercolourists are nervous about trying oils, and I believe that most of this is rooted in the the idea that oils are horribly complicated.

Oil Colour vs. Watercolour

If you look at the side of a watercolour tube, let’s say Ultramarine Blue for instance - you’ll see a little pigment code, in this case PB29. You’ll find exactly the same code on the side of an oil tube, which means that if you know how Ultramarine Blue ‘works’ in watercolour, then you can rest assured it’ll be essentially the same in oils.

This means that if you regularly use Ultramarine Blue in your watercolour mixes, it will create exactly the same colour mixes you’ve perfected in oils. Extrapolate this to your current paintbox, then if you simply duplicate those colours in oil then all of your watercolour mixing skills can be transferred directly to oil.

So how is it different?

Simply put oils add an extra dimension to your current watercolour skills, specifically opacity. So rather than just applying Ultramarine Blue in translucent washes you can opt to lay it down more thickly, or even as a textured paste.

By using just a single colour in glaze, body and impasto you can create many more visual effects than are possible in pure watercolour, and it is this creative potential which makes oil paints worth learning. Once you extend your palette to a few colours, oils will open a new creative language in which to work.

Oil painters generally call thin washes ‘glazes’. Thicker, more turbid paint ‘body colour’ and very thick or textured paint ‘impasto’.

The greatest difference between oils and watercolours is drying time of course, however if you avoid using fat buttery oils and use a fast drying medium such as Galkyd or Liquin your paints will be workably dry relatively quickly.

Initially avoid adding extra oil to your tube oil paints, in the form of an oil and solvent medium or any kind of oil (linseed, stand, poppy, walnut, safflower etc). Tube paints are already as full as they need to be with oil, and adding more will have disastrous consequences for the drying and handling properties of your paints.

When oil is added to paints by experienced artists, it’s generally to facilitate a bit of subtle blending, add a little lustre or retard drying for extended blending; none of these things should be on your to do list yet.

Oil Mediums

Oil Mediums are what you should add to your paints instead of pure oil or solvent. They help you to manage the paint’s rheology (working properties), drying rate and lustre. When using an oil medium, the most common mistake which watercolourists make is to substitute it for water in their technique.

Oil mediums should generally be added in small quantities to tube paint, if you use too much you’ll get into trouble. While oils can be diluted with a little solvent, or a half solvent - half medium mix, it is generally best to try to apply them as thinly and dryly as possible. When you need to use a wash of oil paints (a ‘glaze’ ) this is generally quite viscous and not at all runny.

Working Window

As a watercolourist you’ll know that every technique has an optimum working time or window, usually when the paint or paper is wet enough to get the effects you want, but not so wet that they won’t stay put. In addition to this some watercolour effects, particularly randomising ones, depend on placing the paint in the right way at the right time to get the best results.

Oil painters call the working properties of oil paint (thickness, liquidity, stickiness oiliness etc) its ‘rheology’. And just like watercolour there’s an optimum time to work into washes, scratch into wet paint, or get a good blend. In this respect oil paints are generally more forgiving than watercolours, so if you can manage the active surface of an full watercolour sheet, then oils should be an absolute breeze.

Traditional oils are very similar (almost identical) in terms of their working window as watercolours, whilst more contemporary oils - where fatter buttery paint is used - are very different.

For this reason I recommend that watercolourists start by trying more traditional oil painting techniques and don’t dive straight into using thick blobs of tube oils applied with a knife or square brush.

By building on the skills you have, and utilising ideas you understand (such as the importance of retaining a glow from the white ground), watercolorists generally exceed their expectations if they try a traditional oil method.

Conversely when watercolourists take on a more contemporary oil method, they can get overwhelmed by the opacity and stickiness of oils squeezed directly from the tube. I’ll discuss how to manage these issues in my next article, aimed at Acrylic to oil painters.

An easy Oil method for Watercolourists

Many great oil painters used watercolours, or watercolour techniques in the practice, so it makes sense to emulate a few of their methods as you extend your skills to oils. Here is a simple way into oils for watercolourists.

Watercolour Distemper.

Early oil paintings evolved from ‘tempera’ paintings, that’s to say layers of oil paint laid over an aqueous underpainting such as egg or starch tempera. In this ancient sense watercolour is a type of ‘distemper (an aqueous paint bound with glue), making it a practical base for oils. There is no reason that you can’t apply your watercolours to a canvas prepared with a water based gesso and then building oils up on top of them.

Turner ( a wonderful watercolourist), was a great advocate of the method, although I don’t recommend that you follow his example of placing water based paints over oils (it subsequently fell off!). Here’s a checklist for this method:

  1. Get a canvas primed with an aqueous (acrylic and chalk) gesso, those sold as ‘suitable for oils or acrylics’ are generally fine.

  2. Paint on it with your watercolours, and let it dry

  3. Using the same skills, extend it to oil glazes (these won’t wash the watercolour off)

  4. Then add slightly thicker, more opaque paint (‘bodied colour’)

  5. Finally add the thickest most opaque bits (‘impasto’)

You’ll note how much richer the colours become at stage 3 (glazes), how some opacity makes your picture more ‘solid’ at stage 4, and how strong impasto can look at the final stage.

If you’re stuck for inspiration work up a study from Turner, Constable, Sargent, Degas, Cox or any of the great artists who used both watercolours and oils. In my next article I’ll look at how oils can solve those perennial problems for acrylic painters, hard to blend and flat looking paint.

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