I am about to replace my small window`s glass and have been offered perspex or polycarbonate (as in bus shelters as I was told)> Which would be better to resist crazing and marks??
Perspex is more flexible, but not so UV resistant. Polycarb is strong, but the strength comes with brittleness. If you can get glass cut to size and then toughened. Most glaziers can do this for you.
All acrylates (ICI Perspex included) are subject to ultra-violet degradation. There`s plenty of uv where boats float! Yellowing is the most obvious sign but embrittlement isn`t so easily seen. Poly carbonate is considerably better in all respectd except cost. Crazing, uv and chemical resistance are a class apart.Hang the cost- safety and security is what counts. If you can find the repairers for seriously damaged bus shelters- do a deal. I picked-up a load of manufacturers discontinued (hatch) transparencies some while ago from Aladdins Cave barge chandlery at the top of the Hamble. (no connection). GL
I've had 3mm Polycarbonate for 30 years, it's still good only problem has been that the surface has been pitted by salt so it lets in light but you cant see out unless it's wet.
As a comment, Perspex (acrylic) is harder and wont scratch so easily, but will break on impact. Polycarb is softer and scratches easier but won't break.
