On 21 Jan 2009, at 11:07, Jane McGary wrote: > Regarding cold frames, UIi mentioned "polycarbonate (Plexiglas)" but > I think these are two different things, at least as the terms are > used in North America. Plexiglas is polymethylmethacrylate, and is a fairly old product. Lexan is a polycarbonate and was first introduced in the early 1960s. -- Rodger Whitlock Victoria, British Columbia, Canada Maritime Zone 8, a cool Mediterranean climate on beautiful Vancouver Island http://maps.google.ca/maps/…