Can I Mix Different Brands of Gouache?

Rei asks:

Is it alright to mix gouache of different brands? I have some Winsor and Newton gouache in primary colors, but am interested in trying other brands because of the differences in ingredients, to see what best works for me. Would I be able to mix my white and black W and N gouache with other brands and have an okay turnout? I am not certain because of the ingredients, and would rather not buy paints if they will not mix well with the Winsor and Newton I already own.

Yes you can, Rei, absolutely! I always mix different brands of gouache.

Not only can you mix different brands of gouache, but you can also mix your gouache with watercolors. They're all water based, of course, and both the gouache and watercolors use the same binder, which is gum arabic.

I sometimes start a picture in transparent watercolor and bring in the opaque gouache gradually as I need it, to cover up mistakes, add accents, or flatten passages.

I have even combined transparent watercolor pigments with acrylic matte medium to create an impermeable glazing layer over a casein painting. But be careful of your brushes if you use any acrylic, casein, or cel vinyl in any mixture because those binders will wreck a brush if it dries with paint on it. As always, I'd recommend that you do experiments on test scraps and see what happens with different combinations.

As for which brands to mix with your primaries, I would recommend Holbein's gouache set, M. Graham's watercolor or gouache sets, or the gouache set by Daler Rowney. To read more about kinds of gouache, check my previous post: Gouache Ingredients from Manufacturers.
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PDF of Recommended Gouache Materials