Which decorating technique involves writing on vellum paper or mylar plastic?

The technique that involves writing on vellum paper or mylar plastic is known as overlays. This method is characterized by the layering of materials to create depth and visual interest in calligraphic works. Overlays often allow for a unique interplay between the background and the written text, enhancing the overall aesthetics of the piece.

Vellum and mylar are both materials commonly used in overlays because they provide a smooth surface for writing and allow for transparency, which can be leveraged in creative designs. By layering text or decorative elements on these materials, artists can achieve effects that are not possible with traditional paper alone.

Calligraphy, while it encompasses the art of beautiful writing, is not specifically tied to the use of overlays or the materials mentioned. Illumination refers to the decoration of manuscripts with ornate designs, particularly gold or silver leaf, while engraving involves cutting into a hard surface, making those options less applicable to the question.