Medium refers to what binds the paint (clear, pigmentless acrylic). It does not necessarily have to be gel medium, medium can be thin, thick, etc.

After some time I have come to use it like water, not even mixed like in the video, and don't really have any fear anymore of using too much. Part of this is because there used to be a suggested max 50% *water* suggestion but that's no longer really the case (google How Much Water Can You Safely Add to Acrylic Paint? by Golden). Yes this is a different chemical, so it's good to be cautious, but you can always do your own adhesion tests like the one's Golden does to be sure since what paints you use and what you're painting on are huge factors in adhesion. If you're painting like watercolors on paper none of this really matters. And for glazes, etc, imo water is usually what you want since you want them to dry faster.

please watch the video carefully. do NOT use glycerin, it will never dry properly, what you want is propylene glycol. and i haven't used gouache so i wouldn't know

That's exactly what iam looking for, a retarder for gouache. Winsor and Newton have a medium called " Watercolor Blending Medium " and it is a retarder for watercolors. It works well on Gouache, and triples the working time. The only problem is, EVERYWHERE IS OUT OF IT! out of stock on Amazon, Blicks, Jerry's, Jackson's... everywhere! I already have jugs of propylene glycol... iam thinking it is simply H20, PG & a tiny amount of glycerin. I tried looking up their SDS, and it isn't filled out at all! It says " NA" or " doesn't meat the standards to test " So yeah, I was hoping he would have have a recipe for a retarder, and for different mediums. Iam just gonna have to start running tests and experiment with it.

i found it made gouache sticky ! probably because of the binder used