Short answer
Gouache and watercolor are both water-based paints made from pigment and a water-soluble binder, usually gum arabic. The main difference is opacity. Watercolor is transparent, so light reflects off the paper through the paint. Gouache is opaque and matte, so you can cover darker colors with lighter ones. The two work well together.
What they share
- Pigment bound with gum arabic (typically).
- Thinned and cleaned up with water.
- Sold in tubes and pans.
- Re-wettable after drying, to some degree.
- Usually applied to paper, with brushes.
Key differences
| Feature | Watercolor | Gouache |
|---|---|---|
| Opacity | Transparent | Opaque |
| Finish | Luminous, glossy-ish glow | Flat, matte |
| Order of work | Light to dark | Flexible; light over dark is possible |
| Highlights | Preserved paper or lifted paint | Painted on top |
| Correcting mistakes | Limited | Easier by painting over, though re-wetting can lift layers |
| Dry color | Often lightens slightly | Can shift slightly, often darker or lighter depending on the pigment |
Gouache is generally made with larger pigment particles and often includes an added white filler such as chalk, which gives its opacity and matte look. Brands differ, so check labels.
Poster color vs watercolor
“Poster color” (also sold as poster paint or tempera in school supplies) is a cheap, opaque, water-based paint. It is similar in spirit to gouache but is typically lower in pigment quality and less refined. Compared to watercolor, it is opaque and flatter. It can be fine for classroom or craft use, while artist-grade gouache offers better pigments and lightfastness. Terminology varies between countries and brands, so labels matter more than names.
How to paint with gouache
- Choose paper: heavyweight watercolor paper or mixed-media paper works well.
- Pick a small palette: a few tubes and a white to start.
- Mix with water to the consistency you need: creamy like milk for flat fills, thinner for wash-like effects, thicker for opaque coverage.
- Work from mid-tones, then build lights and darks: because it is opaque, you can add highlights last.
- Let layers dry before adding more: wet layers can lift or mix.
- Test colors on scrap paper: gouache can dry to a slightly different value.
Thick paint on flexible paper may crack, so keep very heavy layers modest.
Using the two together
Many artists begin with transparent watercolor washes for sky, shadows or backgrounds, then add gouache for opaque details, highlights and crisp shapes. Tips:
- Let the watercolor dry fully first.
- Use gouache sparingly on top, since heavy re-wetting can lift the layers beneath.
- Remember watercolor’s golden rule of working from light to dark, as commonly taught, still applies to the washes. Gouache lets you break that rule for final touches.
- Keep paper heavy enough for wet and thick layers.
Common problems
- Muddy color: often caused by too many layers or overmixing.
- Lifting: re-wetting dry gouache can pull up paint beneath.
- Streaky flat areas: use a consistent, creamy mix and avoid over-brushing.
- Color shift: test and allow to dry.
Which first?
If you love luminous washes and loose landscapes, begin with watercolor (see watercolor painting basics for beginners). If you want bold, flat, graphic shapes and an easy way to correct errors, begin with gouache. Both are compared with other options in our best paint medium for beginners guide, and watercolor’s contrast with a very different paint is covered in watercolor vs oil painting.
FAQ
What is the easiest paint for beginners? Acrylic is often suggested, though gouache and watercolor are also beginner-friendly in cost and cleanup.
What is the golden rule of watercolor? A commonly shared guideline is to work from light to dark and preserve the lightest areas.
Can gouache be used like watercolor? Yes, thinned with water it behaves in a wash-like way, but it stays more opaque and matte.