The only advantage is the stability of the mask with respect to temperature and humidity variations. The standard Mylar artwork is very sensible to humidity and temperature, for example:
- Temperature effect 16µm/°C/m with very small hysteresis effect.
- Humidity effect 8µm/%RH/m with important hysteresis effect. For example if your artworks are manufactured and stabilized in a room at 20°C and 45% RH and you use them at 24°C, 53%RH, for a 700mm artwork the possible distorsion will be :
((24-20)*16+(53-45)*8)*0.7 = 128µm.
Glass artworks are less sensible to temperature, and humidity has no effect.
- Temperature effect is 4µm/°C/m The resulting effect for the same dimensions is : ((24-20)*4+(53-45)*0)*0.7 = 16µm.
This is the main reason to use glass artworks. On the other hand, the price of glass artworks is much higher. In most cases, working in a stable clean room, with good exposure units controlling glass temperature as the ones provided by ALTIX - Automa-Tech™, provides a good solution and prevents from using expensive glass artworks.