Amazon.com: Flat Acrylic Paint Brushes Set-6pcs Synthetic Japanese Nylon Artist Bright Paint Brushes 1/2 Inch Wash Brush for Acrylic Painting, Oil, Watercolor, Gouache Face Body Nail Art, Crafts, Rock Painting
GOUACHE PAINT BRUSHES and how to clean them + swatching brush types - YouTube
Blog: What brushes should I use to paint with gouache and how to clean them? - Andreia Melo
The brushes and paper that work best with gouache — Lena Rivo