For smooth, non-absorbing surfaces e.g. for glass, porcelain, metal
The adhesion of a smooth surface increases, if it is first sanded flat with fine sandpaper. Apply undercoat. Let dry for 24 hours if possible. Alternatively burn it in in an oven at 160°C for 30 minutes.
For absorptive, porous surfaces e.g. wood, canvas, cardboard, plaster, aerated concrete stone
The undercoat solidifies the surface. The absorptive ability is reduced to an equal measure over the entire area. Test the suitability of the undercoat in an inconspicuous place of the desired surface.