This invention relates to the partial printing of a substrate with a plurality of layers to form a partially printed panel. Within each printed portion, at least one layer is applied to the substrate with inexact registration in relation to a second layer. A "control layer" comprising "edge sealing strips" is printed so that, within each printed portion, each edge of the at least two layers with inexact registration is located within the edges of an overlapping edge sealing strip. The edge sealing strips may provide a visual seal or mask at the edges of printed portions, for example to enable the each printed portion to have the desired color rendering within a one-way vision control panel. The invention can comprise the physical sealing of printed portions containing gaseous or liquid fluids or particles in suspension, such as fragrances, medication, environmentally reactive materials or security printing features.