Slow drying medium will slow the drying time of acrylic paint. You can put as much of the slow drying medium into the paint as you want.
Warning: Last items in stock!
Slow drying medium:
You can thin the medium with water. Depending on how much you add to the paint the transparency and gloss will be affected. If you want to varnish over a painting where you have used slow drying medium you should wait at least a week before applying it over the top.