I have been using gouache since art school, about 19 years. Before then I painted with acrylics and quickly became a big fam of watery washes and rehydrating paints. At the time, I was not interested in watercolor because I had no idea what a wonderful medium it could be. In my head, watercolors came in round plastic pans and were cheap and horrible to paint with. Maybe I thought all watercolors were comparable to Crayola children's watercolor set.
Gouache is an opaque paint medium. Traditional gouache can be re-wet and re-worked over and over again. The final painting can be reworked as well. Unlike most paint mediums, gouache dries completely matte.
Gouache dries quickly. Very quickly.
There is also a thing called acrygouache which is just a fancy acrylic paint that dries matte. Not gouache in any way.
Getting to know guache again. I forgot how fun it is to paint with thick pasty paint.
Reconstituting gouache is easy. Spray with water and wait one minute or swirl a wet brush until you have a paste again. I always prefer using wet paint directly from the tube but refreshing dry gouache works perfectly fine, especially for layering.