Protector scopes

[Douglas Greville]

Gina

The ongoing problem with the prisms always appears to be the glue
either shrinking or yellowing.

This is something that has plagued US military periscopes and episcopes and
still does. I have seen NOS ones still sealed in their hermetic packets that the glue had started debonding or/and yellowing. Most seem to go no more than 2 years out of the wrapper before they go yellow.

However, I note that I have seen Churchill, Ferret, Saracen and Centurion scopes that were as perfect optically as the day they were made. Most had been in a vehicle or sitting unwrapped on a shelf all that time. So whatever it is that the British are doing and have always done works.
I would like to find out what it is?

The ultimate test of your acrylic glue will be how it withstands normal daylight. This is also the reason why the normal UV setting glues cannot be used for optics. They are fine for home craft work for something that spends its life indoors.

Regards
Doug

Originally Posted by Gina Vampire

What I am able to say is that using acrylic sheet , acrylic mirrors and acrylifix produces very clear scopes and that if clear casting resins are used the same results are obtainable so long as all surfaces are sanded/ground dead flat.