Painting tote bags

I’m making these little white tote bags, painted with acrylics mixed with a fabric medium.

For now, I’ve noticed that mixing one part paint with another of medium makes the resulting substance long lasting but not necessarily nice to use with stencils. And the final painting result is just cleaner if I do it by hand. But it shouldn’t be like that, right? Is my paint too thick or too runny?

Mm… must investigate that.