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En Plein Air

This masterclass shows how to slow down the drying time of watercolour using Gum Arabic, which is especially useful when painting en plein air. Gum Arabic is the binder in watercolour paint and, by adding a bit to your watercolour mixture, you will slow the drying time of your mixture versus watercolour diluted only with water. A swatch of watercolour without any additional Gum Arabic shows how watercolour behaves with water alone, then the Gum Arabic is added directly to the paint. It is easy to see that the paint mixed with Gum Arabic sits on the paper slightly differently: the gloss and transparency is increased, the paint moves more slowly on the paper and it remains open to work with for longer. You can also add a small amount of Gun Arabic to your mixing water and introduce it to your paint that way. Finally, if you apply a watercolour and Gum Arabic mix to paper and then apply watercolour on top of that wet layer, you can control the spread of colour more than if you didn’t use a Gum Arabic mix in the base layer.

Video Transcript
0:08    Hello, I want to talk to you about watercolour painting outdoors, also known as 'en plein air' painting. One of the problems watercolourists face when painting outdoors, especially in hot and dry climates, is that the paint can dry very quickly. So what if you need more time to work on your washes? How can we keep a colour wet for longer?

0:29    This is where mediums like gum arabic and blending mediums can be very useful. Gum arabic is the binder in watercolour paints. So by adding gum arabic to your wet watercolour mix, you're adding extra wet binder, which is going to keep the colour wetter for longer. One way of mixing gum arabic into your watercolour is to mix your paint with water, and then to pick up a small amount of gum arabic and mix it with your watercolour mix before applying it to the paper. Here we can see that the mix containing extra gum arabic stays wet for longer.

1:21    You can also add a small amount of gum arabic directly into your mixing water for the same results. Another benefit of using gum arabic is it has the effect of making the watercolour more transparent. It will also add a slight gloss to the finish and slow the movement of the colour on the paper. And finally, you might want to experiment by applying a watercolour and gum arabic mix to your paper, and then applying watercolour on top of this. You'll notice you can control the spread of colour more than if you don't use a gum arabic mix.

I hope you found this interesting!