Watercolour vs. Gouache Paint – An In-Depth Look

Two very similar media can still yield very different results! In today’s blog post, we’ll be looking at the performance and visual qualities and see how best to use them in practice.

Note: If you’d like to know more about these paints in terms of chemical composition and some fundamental differences, check out this helpful blog post by Eve.

Opacity and Fluidity

One of the first differences is in terms of opacity. Since gouache is sometimes known as “opaque watercolours”, you can already tell that it’s a thicker type of paint than watercolours! 

While it’s possible to dilute gouache so it’s as transparent as watercolour paint, you can also use thicker layers of paint so that you can’t see the paper and colours underneath. There will always be a certain level of transparency with watercolours, which is how they’re meant to be used.

Bonus tip: While you could use watercolour paint straight from the tube while hardly adding any water, it’s not as cost-effective that way, plus you’ll find that the paint won’t flow as well. The paint’s actual colour will also be quite tricky to see.

On the other hand, gouache paint flows well, even when you add little to no water to it! The paint that comes out will also be quite similar to what it will look like when dry.

To elaborate on each paint’s fluidity, it’s possible to use wet-on-wet techniques with both (i.e. wet paint added to a wet surface). However, because the granules in watercolour paint are often much more refined than in gouache, they tend to blend more smoothly and move more freely when wet.

The pigments do mingle a little with gouache, but not as much as they do with watercolour paint.

In terms of layering, both paints layer well, though, with watercolour, you’ll see most of the underlying layers of paint. With gouache, it’s possible to almost completely cover the underlying layers with a thick layer of paint, even if it’s a lighter colour on top of a darker one. 

In short, it’s easier to cover mistakes with gouache paint, while with watercolours, you’ll need to paint a little more carefully or use lifting techniques to sort-of fix mistakes. You can also get sound glazing effects with watercolours since they’re so transparent, which is harder to do with gouache.

Though not impossible with gouache, it’s also better to use wet techniques with watercolour paints.

Watercolour’s Characteristics

Let’s put these two paints to a side-by-side test, shall we?

First off, I decided to paint the same image twice using both paints, starting with watercolours. I typically work light to dark with watercolours and from more significant areas to more minor details.

As you can see, the first layer is always the lightest. It’s okay to be messy since layering dark colours on top will still cover a lighter colour.

You’ll also notice a few paint “blooms” here and there in the areas where the water has pooled on the paper. This causes a slight variation in the paint’s tone, so it’s not one flat colour.

Watercolour’s fluidity means that it’s hard to get a solid, flat colour over a large area, especially when the paper begins to warp from the moisture. This colour variation can be good or bad, depending on your preferences.

Next, I added the subsequent few layers of mid-tones, gradually using darker colours for the shadowed areas. You’ll notice that while it’s hard to see the initial pink layer under the dark blue areas, you can see its influence in the light blue areas.

The last step is always the details and painting in the darkest areas. Overall, you can see that I was able to get relatively similar colour mixes to my reference image (which is a postage stamp). The washes aren’t so flat, but I think this gives the painting some character.

Gouache’s Characteristics

Next is to test gouache paint. Again, I started with the pink colour, working from light to dark and from the largest shapes to the tiniest details.

You’ll notice that I wasn’t as careful with staying within my lines, as I know I can paint over them later. And since this first layer is diluted, the wash is quite uneven, like with the watercolour version.

This is so that I can still see my sketch, plus I do like the variation in colour tone

I layer the mid-tones next, like before. However, unlike before, I’m still keeping some of my brushstrokes loose because I know I can paint over them later if needed.

You may also notice that the paint looks a little “streaky” here, while in comparison, watercolour tends to look a little “blotchy”. This is because gouache is thicker and heavier, and its pigments are more likely to follow your brushstrokes and stay in place during painting. Watercolour will flow wherever gravity and water take it, thus creating a more random effect.

Note: I’m using a thicker consistency of gouache paint here, though it’s still not as thick as it can go.

I did one final layer with thick gouache paint to complete this painting. You can tell immediately that the colours are much more solid, and the underlying layers aren’t visible anymore. The final details I added were the light pink highlights, which are only possible because of the gouache’s opaque nature.

Side-by-Side Comparison

Let’s put these two paintings side-by-side for a proper comparison! Both were done on the same page of hot press watercolour paper, and I tried to use similar colours as I could find and mix.

As said before, the watercolour version was a little blotchy due to its more fluid nature. This creates a visual texture of water, which isn’t found in the gouache painting.

Note: This texture will be different when using cold press or rough watercolour paper. It’s only like this here because of the smoother hot press paper.

Another big difference is in the transparency of the watercolour painting compared to the gouache one, as you can still see the underlying layers of the former. In addition, watercolour relies on the white of the paper to give it its luminosity. At the same time, the gouache paint looks bright by itself, which is especially notable in the light blue areas.

Overall, watercolour and gouache paint may feel a little similar in usage but still have their unique traits. It boils down to what you want out of your paints and your preferred paint properties.

If you prefer a lighter, more natural and fluid medium, go with watercolours. If you prefer something solid and more illustrative, gouache is for you. Or if you can’t decide which one you like more, then paint with both! The skills and techniques used for these paints are similar enough to be transferable, with most tweaking related to water control.

In any case, the biggest thing is to learn and have fun! And that already will be the best takeaway from this blog post.

Do you prefer watercolours or gouache paint? What are the most significant differences and similarities between the two? Let us know in the comments below! Also, for more tips and tricks about art, feel free to subscribe to our email newsletter. We’ll also keep you up to date with new products and workshop releases.

Nicola Tsoi is a practising graphic designer and illustrator based in Hong Kong. She likes to watch birds do funny things, search for stories, and bake up a storm during her downtime. She keeps a pet sourdough starter named Doughy.