We have been picture framing for close to half a century and we have come across much disinformation and many fallacies where custom picture framing is concerned. Perhaps the most persistent fallacy is the widespread and popular misconception that glazing ( the covering of framed artwork with a transparent or see-though material ) with 'Plastic Glass', 'Perspex' , 'Plexiglass', a clear plastic, or an acrylic pane  is  a cheaper more convenient and better alternative than glazing  with clear float glass.  Alas, and in our lengthy and not inconsiderable  experience ...