Some call gouache opaque watercolor, but it’s more complicated than that. You may want to buy only gouache and use it like watercolor, and on some occasions, you can, but you can only partially replace watercolor with gouache.
Pigment particles have different sizes.
Gouache is a water-based medium, so you can thin it with water, but the resulting color won’t be as transparent as when you use watercolor. Both gouache and watercolor are made with pigments and a binder (usually gum arabic), but pigment particles are larger in gouache and have a higher concentration in the mix. This makes the color more opaque and less transparent than watercolor. Gouache also dries faster than watercolor, so there is less time to blend different colors seamlessly.
The size of pigment particles in the gouache makes the paint sit on the paper more than soak into it like watercolor. It’s an advantage when you want to remove paint in some parts. But it also makes the paint more difficult to blend. The thicker consistency of gouache can be a disadvantage when you want to create transparent layers because it tends to sit on top of the paper instead of sinking in like watercolor.
To use gouache like watercolor, you should use watercolor paper, as it will be watery!
Making transparent layers.
You can add water to the mix if you want to achieve transparent layers with gouache. This will add space between the pigment particles and allow the light to bounce back, making the paint transparent. You will lose the intensity of gouache colors by adding water, but it will still be more intense than watercolor paint.
Watercolor effects with gouache.
The beauty of watercolor is when you allow the water to do the work for you, letting the pigments flow and merge into each other. You can achieve this effect with diluted gouache, but due to the size of pigment particles, the flow will be less important than with gouache. You can help the pigments to move on the paper by adding a spritz of tap water.
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Steps for an abstract watercolor landscape
To paint an abstract watercolor landscape with gouache paint, follow the steps:
- use watercolor paper, minimum 300 gsm
- wet the paper on both sides so that it will stick to the desk
- apply gouache paint in thick consistency, straight from the tube in different places, giving an abstract shape. It’s easier to begin with the horizon line and build from it
- be quick, you don’t want the paper to dry
- using a mop brush, add a lot of water to the edge of the paint, allowing the pigments to fuse in the water
- you can add more paint to the poodle (yes, it will make poodles!)
- for reflections in water, use a dry flat brush and brush the paint while it’s wet to the bottom side of the paper
- to help pigments fuse even more, spritz from the side with tap water
- you can remove some paint with clean tissue to create clouds
- let everything dry naturally (no hair dryer or heat gun here, it will make your pigments move in a weird way), this may take hours
You can watch this video for step by step instructions:
You can also mix watercolor and gouache in the same painting to get the best of both worlds! If you want to use gouache as a base and add watercolor later, it’s better to do the opposite and use watercolor first, then add gouache on top.