A measuring method includes: illuminating a silicone-coated layer using a light source; and imaging light from the light source that is specularly reflected from the silicone-coated layer to form an image of a surface of the silicone-coated layer. The method further includes detecting pores and/or voids in a silicone coating of the silicone-coated layer from the image; determining a silicone coverage of the silicone-coated layer based on the detected pores and/or voids; and determining a release force of the silicone-coated layer based on the silicone coverage.