Re: Xenon Flashtube was Re: PPG Starphire Glass ( ?? Questioning My Data)

----- Original Message -----
From: "Marek Matusz" <marekmatusz@hotmail.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Friday, November 18, 2005 1:07 PM
Subject: RE: Xenon Flashtube was Re: PPG Starphire Glass (
?? Questioning My Data)

> Yves,
> I would say build or buy a reliable UV source to start
> with. A lot of people on this list use banks of BL tubes.
> The do not generate heat, have high UV intensity (short
> exposures!) and as Loris pointed out are inexpensive to
> build. I have been using them for several years now for a
> number of alt processes including gums.
> Second, sieze your paper with some hardened gelatine.
> After that you can use any middle of the road gum recipe
> and it will all work for you. You can even experiment to
> your heart's content to discover why we all agree to
> disagree about gum printing.
> Have fun at it.
> Marek, Houston
>
   A brief note about BL and BLB lamps. These are gaseous
discharge lamps similar to standard flourescent lamps
without the internal flourescent coating to produce visible
light. Lamps of this sort like to run hot. While they
generate a lot less heat than an incandescent lamp they
still get warm. The efficiency, and thus brightness, of the
lamp goes up with its temperature. Lamps of this type like
to be run continuously. Older lamps seem to have more
variation with temperature than new lamps. My point is that
for shortest exposure the lamp should be well warmed up
before starting. Some sort of cover can be used to begin the
exposure rather than just turning on the lamps. I may be
telling people here something they already know and practice
so I appologize if that is the case.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com