From: Ed Stander (glassact@compuserve.com)
Date: 12/11/01-07:06:09 AM Z
Folks:
Glass tends to absorb UV. Plate glass lets nothing through below 330 nm.
On the other hand, Quartz glass (no soda-lime or lead) is virtually
transparent to UV. I imagine that, in their french way, the Fressons are
noting that their enlarging lens and film holders are made of quartz glass.
I have used an OLEC 1500 watt unit to make direct gum prints. I placed
the unit above the enlarger housing with a small fan in between and had no
problem. Light output was reduced, however, to 1/2 its expected value
(measured with a UV meter) due to absorption by the system. Cheers, Ed
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