For a couple of years I abandoned watercolour painting entirely as I was concentrating on my oils, but then I rediscovered the thrill of sketching outdoors and found that watercolour was the easiest medium to take with me and it made for quick sketches and was a great way to capture the moment.
But then I grew frustrated with the limitations of pure watercolour – especially having to paint dark over light and having to carefully plan and paint in layers. I longed for the freedom that oils had given me. With them I could go in light over dark or dark over light, I could cover my mistakes, I could create a nice solidity to the painting. In short I could paint with my heart and not with my head. I wasn’t so bound by the rules.
What I was bound by however was the kit. There was always so much more to carry with oils. So, I asked myself, was there a medium that was compact and lightweight and that would give me the freedom of oils? And that was when I discovered gouache.
I loved it! And I still do. But I began to struggle with the fact that the paints in the palette dried out too fast and often crumbled and became useless. I didn’t want to carry tubes around with me (more stuff to lug around!) and sometimes I even wanted the translucence of watercolour as well as the flat opaqueness of gouache. What to do?
The solution!
I was looking at the work of Marco Bucci whose plein air work I greatly admire. Check him out here on Youtube painting outdoors and see his technique of adding a little white gouache to all his watercolour mixes. The process and the end result were exactly what I was looking for.
Now I just needed to test it out.
Was watercolour paint mixed with white gouache as good as pure gouache on it’s own? Or would it make everything look pale and pastel?
Let’s take a look. I don’t want top bore you with a chart of mixes, so instead I’ve chosen the less scientific method of sharing a couple of sketches, one in gouache and the other in watercolour plus white gouache.

Here’s an outdoor sketch I made in pure gouache. The colours are solid, flat and opaque and you can see where I have painted light over dark.
And here I have used watercolour and added in white gouache where needed. I get the best of both worlds! I can paint light over dark (as I did with the leaves and flowers in the pots) and can contrast opaque with transparent washes to great effect.

Most colours here had some white gouache added to them to give them body, but in a few places it is just pure watercolour.
The gouache paint has not particularly lightened the watercolour when I have just added a small touch of it to the paint, but it has made it opaque.
My conclusion:
I really think that for me I have now found the perfect solution to the way I want to sketch. I can carry a small palette of watercolours and a small tube of white gouache and be able to paint from the heart in a kind of unstructured way that is unrestricting and fun. That suits me!
As ever, I’d love to hear your comments and views on this subject. Have you tried this mix of gouache and watercolour? What do you use for sketching? Please share your thoughts with us here.
(If you are interested in painting in gouache then take a look at my online course)
Yes, I agree, there are problems with gouache, even though I have successfully used it en plein air before. The trick is to keep painting and keep topping up the wells, but you can’t leave it for more than a couple of days, so the pressure is on! I think the solution of mixing the two materials works well as a compromise, and also allows for each to shine in their own way.
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I agree it is the perfect solution for the joy of outdoor watercolor. A gouache palette requires constant spritzing with water, or glycerin water to be useful. Even at home, I am giving up using my tiny airtight gouache palette because it goes dry if I don’t use it daily.
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