We find acrylic scratches easily and polycarbonate will yellow with time. A tower clock or street clock is meant to be a center of attention for decades if not centuries. Glass does not deteriorate with time. Tempered glass is relatively strong and will only break if hit with a sharp object. It then breaks into small pieces. This is the same material used in the side window in cars. If not properly installed acrylic and polycarbonate will warp. If required in areas prone to vandalism polycarbonate and/or special acrylics crystals are available.
Left – aged crystal removed during clock renovation. Right – warped & scratched crystal.
