Quote Originally Posted by Dan Fromm View Post
Steve, acrylic is hygroscopic, will take up water from the air. Probably not a problem with y'r camera because the relative humidity is the same on all sides of y'r bits of plastic, but the reason that acrylic sheet makes a very bad aquarium cover. The water side takes up more water than the air side and the sheet warps badly.

But acrylic is less impact resistant than polycarbonate. Have you considered using polycarbonate instead of acrylic? I mean, both are equally machinable ...
Thanks for the advice but the only information I’ve found regarding water absorption is on aquatic forums where acrylic has been used fully submerged in tank sumps 24x7. The manufacturer stats suggests very minimal absorption over the life of the material. Also, the Chroma is made using multiple layers bolted together rather than single large panels so again, I think it’s highly unlikely that any warping will occur. As above, I have an acrylic unit in my garden all year round that has very long flat panels and have seen no ill effects.

With regards to polycarbonate, I’ve never seen it in sheet form in anything other than transparent finish (as it generally replaces glass). As a result, it’s not suitable for a camera, hence the use of laminated coloured acrylic.