Gouache shares similarities with watercolour paints but there are a few key differences. Both use finely-ground pigments, but gouache pigments are slightly larger, allowing for more opacity and richer colours in paintings. While watercolour relies on gum arabic for binding, gouache incorporates additional binders like dextrin or cellulose gum for its characteristic matte finish and opacity. That said, some gouache formulations still include a small amount of gum arabic to improve water solubility and reactivate dried paint.