My poster colors (& some gouache) are getting a bit thick and I know not to over-thin with water. Should I thin with gum arabic and water or ox gall or a mixture?
Since gum arabic is the binder, I would think it would be used at least in small quantities but I also want a bit of the qualities that ox gall would give. Should I get a small bottle of each and mix them?
It’s okay to use water for those. Where you want to be careful is with acrylics because that will reduce adhesion. If you add water to your poster paints or gouache you’re just replacing what has evaporated. I like to use distilled water and put in several drops, then cover and let it soak in for a while. Repeat and stir until you get the consistency you want.
We had a gouache illustrator at a watercolor society meeting who used jars and they would get quite dried out. He just wet them before use.