Add a few drops of silicone oil in the preparation (1/2 cup of DEMCO EnCouleurs casting medium + a few drops of fluid acrylic + 3-4 drops of silicone) and pour the mix on the surface to be painted. To see the cells appear, gently scrape the surface with a paint knife. It will be necessary to wipe, with a cloth, the excess silicone accumulated on the surface, once dry.