Monday, 22 May 2017

Painting leaves: Colour Mixing

Nothing spoils a botanical painting so much as poorly painted or inaccurate leaves. If we think nobody will notice our errors, we're probably mistaken. It doesn't matter how well we painted the rest of the piece - it's only ever as good as the weakest part. But leaves can be tricky! for me the likelihood of success increases if preparatory studies are completed. I try to work out colours and approach before I even think about starting the painting. The idea for this blog post occurred to me as I gathered my thoughts for a class taught last week for Field Breaks at The Art Room in Barlow, and, as always, it was interesting to hear what problems students encounter when painting leaves. One of the most common cited is colour mixing, so this is my focus here - although I may cover others leaf painting problems in a future posts.

picture of ivy watercolour
Ivy leaf painted as preparatory work for the class. I light the subject using a lamp positioned upper left, to enhance the light and shade. The first study is on paper and used  to work out colours and approach, before moving on to vellum. I laid 3 green washes with a size 6 brush, over an initial cobalt blue wash, which was painted with a size 10 brush. I  then worked with dry brush, using size 1 spotters and miniatures to deepen colour before picking out detail with a fine pointed David Jackson brush. I also use a Pro Arte synthetic flat brush for tidying and painting shadow under the veins
Process of painting and ivy leaf on vellum in stages
Moving on to vellum: I started by lightly painting in the veins with Winsor lemon. Then painted a rough wash of cobalt blue with a size 10 brush, this is the underlying colour and makes a good shine on a dark leaf. I left virtually no white, because the blue will be much less obvious once the dark green in on top, however, the blue highlights must be preserved to give the effect of shine. It really doesn't look great at this stage but this is just a foundation,  the wash is graded to give some indication of form. I paint around the veins with the cobalt and leave the outer edge of the leaf very soft, to enhance the form as the leaf bends away from view.  From there on, the approach differs from paper, and the whole leaf is painted using dry brush techniques. I use a mix of three colours for all parts, Indanthrene blue, Transparent Yellow and Permanent Carmine. I came up with a system on working with the light value of the blue as the predominant factor when deciding on the colour mix....basically a dark green leaf needs a dark blue's that simple! (see the chart below).  Always work with transparent colours in the layers on dark leaves. For light coloured leaves, use a high light value blues instead, such as Cerulean or Manganese blue (transparency is slightly less important in high light value colours). For the mid green leaves  for something like a Cobalt blue or Winsor blue. The browns are mixed with the same three paints, simply increase the ratio of the red and yellow to make brown.
Finished painting of an ivy leaf on vellum
The finished leaf on goatskin Kelmscott. Colours are gradually deepened so as not to be heavy on the vellum. Soft strokes with barely any paint at all are used to build form and colour and highlights are maintained. I use a technique, which I refer to as 'polishing' to smooth the surface and you will see that I preserved the blue on the highlights by carefully blending around the highlights.

I'm not going to list lots of colour mixes here because that not very helpful when you consider how many variables there are in the ratios. My approach is aimed at understanding the basics of colour mixing, so that you can easily work out yourself what to use. Here's my method, it's not intended to be a hard and fast rule but more of a method for guidance..... There are, of course, lots of other ways.

An approach to colour mixing:  I mix all greens from primary colours, blue, yellow and usually a small amount of red. A few years ago I developed a simple system based on the light value of the blue as the predominant factor when deciding on the green mix.  
 Below is a chart for greens and browns that I made using 3 primaries of varying light values. The blue is the colour to choose first for a green mix because it's the dominant colour. The light value and saturation of that blue is all important. If you start painting a very light green leaf with a darker value blue, such as French Ultramarine,  you may well run into problems with the leaf becoming too dark. Any single colour reaches saturation after around 4 washes, so it will become fully saturated quite quickly, adding subsequent layers of the same mix just makes paint thicker but not darker. So, if you bear in mind the light value of the blue first, you can avoid this problem. It sounds obvious but it's a surprisingly common problem, especially with beginners. Then choose the yellow and finally most greens mixes have a small amount of red, so choose this colour last. The same rule of light value applies with all three colours When you mix in so much red that it turns brown the red becomes the dominant colour instead of the blue.
A green and brown colour chart with leaves
My Rule of Thumb Light Value Chart. If you base your green mixes on the light value (i.e. tonal value) of the leaf colour that you want to achieve by choosing the blue first, you can't go too far wrong. So for a light coloured leaf choose a light blue such as cerulean (top row of chart) and for a mid light value, such as cobalt blue (middle row). The ivy leaf was a dark green, hence the choice of the darker more saturated blue, Indanthrene (bottom row). You can see how easy it is to put the leaf on the chart to find a close match.  I mix 1:1 ratio of blue and yellow first, then 2:1 and 1:2 with the blue and the yellow, thereafter I start to add a small amount of red and play with the ratio of the 3 colours.  The  red generally mar a more natural green.
Paintbox with pans of watercolour and ceramic palette
My old paintbox
I use a primary palette of single pigments paints with 4 yellows, 6 blues and 5 reds. This palette allows me to mix any colour that I might need and makes it more manageable to understand colour mixing.
If you don't understand the light values or saturation of your paints, try this exercise below, it's one Ruskin used to ask students complete. Fill the brush with each of the blues and paint down the page observing how dark each colour is as it progresses down the page, you will see the saturation of the darker colours allow you to keep going much longer, whereas the light value of cerulean has already disappeared. You can easily see the tonal difference between the colours.
tonal value of blue paint painted
Tonal values of the blue paints, left to right: Cerulean, Cobalt, Winsor blue green shade, French Ultramarine and Indanthrene. I've also turned the image to black and white to highlight the tonal values difference.

For the ivy, the darkest blue in the palette is indanthrene blue and this is the obvious choice, I then chose, transparent yellow, its a rich yellow but most important is the transparncy, especially when painting dark colours. Opaque yellows are not good in dark greens as the block the light and deaden the green, thereafter, permanent carmine was an obvious choice because of its richness.

paints chosen to mix green on ceramic palette
For the green mix the blue and the yellow at a 1:1 ratio and then add a small amount or the red, I can bias the mix to a warmer (more yellow biased green) or to a cooler ( more blue biased green) very easily by shifting left or right with the mix out of the puddle shown below. Adding more red reduces the brightness of the green until too much is added and it shifts towards grey/ brown.
mix of paints to make brown on palette
The exact same colours in a different ratio make brown. Start with 1:1 of  the red and yellow and add a small amount of blue to make browns. A whole range of lovely browns can be made by playing with the ratio of colours.
paints used to mix neutral tine on the palette
Finally using the red and blue at 1:1 this time and adding a small amount of yellow makes neutral tint or as near as black as is possible. As before some lovely variations are possible by varying the ratio of the colours to make warmer or cooler variations.
As you can see from this demonstration above, it's possible to achieve pretty much everything using these 3 colours, including all the various green tones as well as the brown parts without any need for additional shade colours. I used a different underlying blue for the highlights and a cooler yellow for the veins. But this will vary from leaf to leaf.  It's also incredibly important to maintain highlights and this is easier if you use directional lighting on your subject, I often exaggerate the lighting to make the painting more interesting.....but that' a subject for another post.

Finally, I think we all struggle with leaves and if you know that they are a weak point for you, the best approach is to work extra hard at improving them. If you plan to enter a painting for a juried exhibition, bear in mind that judges are drawn to leaves like radar!...... they will notice poorly executed leaves or those treated as an afterthought.

Quick Leaf Check list

  • Observe first - look for underlying colours and key features, such as widest point, tip, base and leaf margin.
  • Make an accurate drawing observing key features and taking measurements 
  • Light the subject using directional light from a lamp or window. A lamp is often better for beginners because its consistent.
  • Work out the palette, is it a light medium or dark leaf? If it's a green leaf, whats the most appropriate blue to start with, test the combinations.
  •  Work out the approach and techniques, underlying colour, graded or blended washes and dry brush.   

A Few Things to Avoid!
  • 'Tram line' veins - check the width of your veins against the actual subject, if too wide use a synthetic short brush to 'push' them in
  • Go easy with the eraser! I hear a lot of people blaming the paper for ragged edges and yes there are a few issues with some papers but nothing wrecks the surface like an eraser.
  • Stylised appearance– lack of detail or inaccurate venation pattern. Close observation required!
  • Over-painted edges, an absolute no no! be careful not to let washes run over the edge. if this happens its usually because you use too much water. Use a magnifier to help avoid this.
  • Poor lighting - results in flat lifeless leaves, interesting paintings always have good lighting. So light from upper front left or right and play with the light until you get it right.
  • Poor tonal values - usually caused by 1: poor lighting 2: bad colour with lack of sufficient variation in tonal values, and/or painting multiple layers of the same colour  3. Painting over the highlights. Light well, start with a slightly larger highlight than needed and check the range of tones and saturation of colour in the subject.
  • Compensatory washes over the top, using colours such as green gold. Unless used carefully and selectively, these can often look like they've been used to compensate for poorly painted leave and can make all of your leaves look the same.
One the second day at Barlow, we painted brown leaves, will discuss browns and reds in more depth later.

Work on Leaves, paint lots of them, paint different types  – paint them over and over don't be in a rush to finish your next piece….  have patience…. It doesn't matter if you didn't post on social media for a while, concentrate on the job in hand and enjoy the process.

image of four differnt paintings of leaves


  1. Thank you so very much! So much good and thoughtful information:-)!

  2. This is an excellent presentation; great for both beginners and a refresher for more advanced artists. Thank you for sharing.