1. 
   Rubylith
   Red-masking material opaque to light, which is used to mask out areas that need to remain, unexposed to light.
   Found op http://www.encyclo.co.uk/local/20829
   
   
2. 
   Rubylith
   Rubylith is a brand of masking film, invented and trademarked by the Ulano Corporation. Today the brand has become genericized to the point that it has become synonymous with all coloured masking films. Rubylith consists of two films sandwiched together. The bottom layer is a clear polyester backin...
   Found op http://en.wikipedia.org/wiki/Rubylith
   
   
3. 
   Rubylith
   Ulano trade name for red masking film.
   Found op http://www.e-printing.co.uk/glossary.htm
   
   

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