Saturday, 7 March 2009

Simon says: oil paints - everything you wanted to know

'Now,' he said, holding up a five foot long piece of card with three tiny blobs of crimson paint at one end. 'Which of these pigments do you think is going to last the longest?'

This was Simon Pierse, yesterday giving the second of his annual series of demonstrations for painting students at the Aberystwyth University School of Art, a lecture-demonstration on everything you always wanted to know about oil paints (but were afraid to ask). But I'm getting ahead of myself. Why three blobs of apparently identical paint? Were they about to engage in some sort of oil-based race? No, they were three different qualities of oil paints: student (budget) quality, artist's quality, and super quality made from original pigments and not synthetic substitutes. A small tube of each sells at the respective prices of £2-4, £14-18, and around £50. 'So this bit here is about 50p's worth,' quipped Simon. And in turn, using a new brush each time, 'to be fair', he began scrubbing out a long stripe of each colour. No prizes for guessing which one stopped first. Surprisingly, the two more expensive paints lasted nearly twice the distance, but very little difference between them in terms of coverage. The most expensive one (scarlet vermillion) was definitely a slightly different shade of crimson, a little more solid perhaps, but if they weren't right next to each other it would be quite difficult to tell them apart.

For those who would like to know more, what follows (when I get around to typing it in) is a digested version of my notes from the talk. Anything beyond this, you'll have to ask Simon yourself - he is very knowledgeable about historical and contemporary painting techniques.

Topics discussed included: synthetic vs. natural colours, permanence, safety, price, colours you need to get started, application techniques, conservation.

Things to consider with oils: strength, permanence, toxicity, cost.

Oils can be absorbed through the skin. Modern student grade oils will generally present no problem, but be careful especially with old tubes of paint you may inherit.

Watch lead in some paints. It used to be that doctors could tell old artists because they had a white ring around their teeth and gums, characteristic of lead poisoning. Lead colours that used to be available include tins of flake white, naples yellow, creminous white (as used by Lucien Freud). Today I recommend you use titanium white which is a brighter white and doesn't age yellow as flake white does. Lead white is heavy and sticky.

Beware also of the cadmium range of colours as these have a level of toxicity.

Vermillion is mercuric and thus very toxic - but it is difficult to buy now.

Most companies have withdrawn the fugitive colours that didn't really last very well. Some to watch that are not permanent include sap green, bright pinks, magenta, and the colours that were new to the Victorains, such as Cotman green, which has turned brown over time.

Prussian blue hue means that the original colour has been matched with modern analine dyes.
Prussian blue genuine means that the colour is made to the old organic or mineral recipe.

Purples tend to be less permanent except for cobalt violet.

There are three basic grades: student grade, artist oil colours, and the series, for example, Windsor-Newton Series 4 (the most expensive grade). Prices vary tremendously between these grades:

e.g. a small tube of cadmium red:

  • cadmium red hue, student grade, typically £2-4, cheap and good to use for impasto work, if you want to trowel it on
  • cadmium red hue, artist oil colours, £15-16, finely ground, will go further, the kind to use if colour is important
  • cadmium red genuine, Windsor-Newton series 4, £50-60, the real pigment, important for the exact colour, or matching for restoration work

Windsor or spectrum red is cheaper than cadmium as a dye.

It is cheaper to buy from the School of Art shop than from shops in town.

There is also a cost difference among the different colours. Earth colours, such as raw umber and burnt sienna, are cheaper. Cobalt blue and cobalt violets are the most expensive colours. Greens are medium priced. Reds, yellows and purples are more expensive than the greens.

What colours do I need?

When working on a painting you want to keep to a strong, rich palette - avoid blending too many colours in a single painting or it will tend to go muddy. Simon often tries to make a painting using only two colours, although he generally has around 20 in his paintbox.

Some thoughts on good colours to have:

2 reds:
A cadmium red, and a crimson red. Alizarin crimson is the most permanent of the crimson reds. Early pigments for red were organic: berries, bark, bugs. Hence the greenish faces you see in some old paintings, where these pigments have changed over time.

A few yellows (2 to start with):
Yellow ochre, cadmium yellow, cadmium yellow pale, cadmium yellow deep. This last is less useful then cadmium yellow light, but it is long lasting.
Indian yellow - this was originally produced from the urine of cows fed on mango leaves. This is quite a different yellow, quite golden and almost orangey - no point using this one impasto, as it really comes alive thin. You can tell whether it is the organic version, not the synthetic one, because it will come dark and concentrated out of the tube.

Viridian spreads well and is the best all-round green, a bottle green. Windsor green is powerful: lighter, stronger and richer.
He didn't say anything about phthalo green, which I favour. It's quite an electric colour, quite evergreen, and never completely washes out of your brushes.

Cobalt blue, or French ultramarine is just as fine. The problem with cobalt blue is that it was made from lapis lazuli, a ground up semi-precious stone mined in Afghanistan, and was therefore as expensive a pigment to use as gold (as in, made from gold leaf). In the 19th century there was a competition to find a synthetic (chemical) substitute for lapis, and a Frenchman won, hence the name French ultramarine for the pigment.
Prussian blue is OK too.
Simon likes to use cerulean blue.

Earth colours
Raw umber, burnt umber. Don't use Van Dyke brown (the oil colour pigment, not to be confused with the alternative photographic process), because it isn't permanent.

Cobalts, mineral colours and earth colours are opaque.

Thoughts on using your oils
If you need a big quantity of paint it is more economic to buy in tins - however, it will dry in the tine so be sure you are going to use it fast. Oil paint oxidizes to dry - like iron rusting, it changes chemistry, and once it's dry, it's not chemically the same thing as before, so remoistening it won't allow you to manipulate the surface of the painting any more.

Oils dry by getting a skin first, so you can still use the paint underneath.

Simon uses an old kitchen top. Bigger is better. You can also use a pane of glass, with a piece of white paper underneath. Tear off paper palette pads are cheap but when you scrape the paints off you can't easily transfer them to the next sheet. This is a problem because when you clean your palette you should first scoop up all the unused paint and sore it at the sides.

Oil paints are at their most stable when squeezed and used directly from the tube, without mixing. But of course the palette is for mixing paint. There is no right or wrong way to do this, but it's easiest to leave the pure colours around the edges of the palette, and then mix them in the middle of the palette.

There are two basic ways of applying paint to the canvas or other surface: fat over thin or alla prima. Fat over thin means that first you sketch in the painting and build up background colours with the paint thinned with turpentine, and later add other layers of paint that are less dilute. Applying paint alla prima basically means that the first layer of paint is the only layer, and you can start working thickly, e.g. with the palette knife, straight away. What you don't wan't to do is put thin over fat, otherwise as the paint dries the colours on top will sink into the under layers, which will suck the oil out of the top layer, leaving a chalky surface.

Oil paint dries the same colour as when it is put on. To test if you've done it right, you can lick your finger and touch the painting when it's dry. If it changes colour, the top layer has sunk - this is not good.

Use white spirit to clean up, and turpentine to thin the paint. Turpentine smells of pine resin, which is evident if you leave it out because it goes sticky. Add more turpentine to the bottle as the day goes on. It should be kept in a dark bottle.

You shouldn't use white spirit with oil paints, because it disperses all the oil, and doesn't leave enought to keep the painting lustrous. In your turps or white spirit bottles you'll eventually find a sludge at the bottom that is dry chalky and dull settles and decant with oil suspension (keep using the same turps after draining away the more pure stuff that doesn't settle to the bottom). Use linseed oil to thin the paints - even better, but be sure to use cold pressed (refined?) linseed oil not the stuff for cricket bats (boiled linseed oil), or it will take ages to dry (as I know to my cost!)

Turpentine and white spirit will eventually break down your brushes. Clean your brushes with white spirit and after with soap and water, and they will last longer.

If you have a turpentine allergy, try zestit, which is a thinner made from lemon etc. It is the green option (in the environmental sense), but it is expensive.

As you build up your layers of paint on your surface, gradually add a little linseed oil to your turps. Use a dark bottle to store your linseed oil.

After your painting is finished
Let it dry, especially if you are working with impasto techniques (thick paint, e.g. with the palette knife). This may seem obvious, but it can take up to 6 months to even a year to dry thoroughly (longer if you are Frank Auerbach).

You need to protect the surface of your painting because eventually it will become dirty. You can do this with varnish. Every ten years the varnish can be removed with an old cloth, and the painting then revarnished. Matt varnish is invisible. If the varnish becomes gunky at the bottom of the bottle, the bottle needs heating. Simon uses matt wax picture varnish which is like a turpentine and bees wax paste. Put it on with an old cloth. It is easy to put on too much. Add linseed oil paste to bulk it up.

A final reminder on toxicity:

Artist quality oils (and acrylics) may be toxic. Particularly vermillion, and emerald green. The latter was made traditionally with arsenic, which went black over time, e.g. in the paintings of Monet. Interestingly, Napoleon was poisoned by arsenic in his emerald green wallpaper during his exile on Elba - upon his death, traces of arsenic were found in his hair.

And finally...

Don't be put off by all this information. Play with oils and enjoy. And remember that you can use any paint for your work - tempera, encaustic, or even cheap emulsion (housepaint) from the local DIY shop (that's hardware & housewares stores, for North American readers).

See also: Simon says: how to stretch a canvas


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Anthony James said...

I had no idea this class took place! No email or poster? I would be very greatful if you could upload your notes, thanks - Anthony J.

Margaret Sharrow said...

I didn't receive an e-mail either - I think it was targeted at second years, but I happened to see a sign on the notice board on the day.

I'll get to putting more of the notes up, as soon as I can!