For example it is often used to mask off areas of a design when using a photoresist to produce printing plates for offset lithography or gravure.

Ulano also produced a yellow-(amber-)coloured masking film called Amberlith that was light-safe only for blue-sensitive emulsions.

[2] Rubylith was used in the early days of semiconductors and integrated circuits manufacturing as stencils to make photomasks (reticles).

A technician would then use a coordinatograph to precisely cut the rubylith (laminated onto a transparent plastic such as mylar) and a knife (X-Acto) to peel the appropriate sections away while it was resting on the light table.

The finished Rubylith mechanical masters were then photo reduced (onto a photographic film) up to 100 times and then step and repeated on to glass plates for production use.