All material shapes have boundaries and how boundaries touch and change speed and direction alter sound . When you layer materials of different types you will alter shear speed and direction. I have done this with many different formula of paint and coatings.
Typically I lay down a layer of blue tape and paint the tape. Cure and listen..then remove and repeat with a different formula. The texture of the paint will also change the laminar flow at the surface. Stick slip on the surface the air will stick to the boundary as if it is wet. I also use magnets to alter material direction of the coating but this can only be done on some material combinations.Tom
Typically I lay down a layer of blue tape and paint the tape. Cure and listen..then remove and repeat with a different formula. The texture of the paint will also change the laminar flow at the surface. Stick slip on the surface the air will stick to the boundary as if it is wet. I also use magnets to alter material direction of the coating but this can only be done on some material combinations.Tom