Know how! [The way you treat Marwitz frames made of the new optyl]

Historical Significance: This booklet probably dates from the 1970s when 'optyl' began to be used for 'plastic' spectacle frames. Cellulose acetate was the most common plastic used for 'plastic' spectacle frames prior to 1975. It is often called zylonite, zylo or zyl in the USA or less commonly xylonite in the UK. Cellulose nitrate was used in earlier times (and also confusingly sometimes called zyl) but is highly flammable and has not been not used for many years. Polymethyl methacrylate (Acrylic, PMMA, Perspex) was used in the 1950s and 1960s but was never a common frame material. Epoxy resins began to be used in the 1970s under the name of 'Optyl' and it was claimed to be hypoallergenic and also less likely to distort CR39 lenses, which had beome to replace glass for spectacle lenses from the 1970s, into a bitoric shape. See: Dowaliby M, Nichols E, Bailey ME.Comparative study involving bitoric effect of hard resin lenses mounted in optyl frames, zylonite frames, and metal frames. Am J Optom Physiol Opt. 1980 Feb;57(2):109-12. and Herzberg J. [Studies on a new epoxy plastic "Optyl" for the manufacture of spectacle frames]. Berufsdermatosen. 1973 Feb;21(1):1-6.