I am currently developing tri-emulsions of wax, water and acrylics as topcoat over an undercoat of developmental oil pastels.. The tri-emulsion blends nicely and flow off the brush is excellent over the oil pastels. Once the water evaporates, the topcoat can be worked with fingers or bristle brush without disturbing the undercoat. i work on bristol paper.
The 'Turtle Wax" formula is green, but emulsified wax is rather inexpensive and white.
Use 5-10% (m/v) of the emulsified wax in acrylic paints you choose.