I use many different things to impress textures into the plaster. As long as I get an object dripping wet, I have no problem with plaster sticking to it.
The photo below shows the textured plaster after it has dried for 48 hours. Now the plaster is ready to be sanded (to eliminate sharp edges) and painted twice with polymer gloss medium to waterproof the surface and to make it stronger.
Below, the sheen from the coatings of polymer can be seen.
Below, you can see that the first color has been added. The paint was added by (1.) rubbing watered-down (thick, creamy consistency) yellow oxide acrylic paint into the textures, (2.) smoothing the paint with paper towels and (3.) erasing areas with a clean, cotton cloth (old tee shirts). When the yellow paint dries, it is necessary to paint another coat of polymer to seal the yellow in place. In the next photograph, I've added a second color (a mixture two differnt hues of acrylic red) and I've painted yet another coat of polymer gloss medium. You can see where I erased the red color and exposed either yellow or white. You can also detect two different red colors (barely - most of the red is quite orange because of the yellow under it) depending on if there is white or yellow under the red coating. I am now ready for a final color and a final coating of polymer medium which I generally change by adding mat medium so that the final work has a satin finish. I work most often with just three colors going from lighter shades to darker ones. I would have this painting done except for the flooding of my studio/basement last night. A transformer blew at 12:30 am and my sump pump quit. I had six inches of water this morning before electricity was restored.