U of S | Mailing List Archive | alt-photo-process-l | Re: Lightsource for Gum Bichromates

Re: Lightsource for Gum Bichromates

Hi Bjørn,

The UV tubes print much faster! Gum under 125 W HPR' needs 6 to 10 minute exposure compared to 2-5 minutes under a UV 20W unit. There are some more differences because the TL is diffuse lightsource compared to the more point source nature of the mercury vapor lamps. you have to adjust your curves when usig diginegs.


On 25 jul 2008, at 09:56, Bjørn Frostad wrote:

Thanks Loris!

I've noticed these 40W's myself - but won't the exposure time be awfully long compared to a 125W bulb...?


----- Original Message ----- From: "Loris Medici" <mail@loris.medici.name >
To: <alt-photo-process-l@usask.ca>
Sent: Friday, July 25, 2008 7:55 AM
Subject: Re: Lightsource for Gum Bichromates

My bulbs also are Philips brand. I use 24" (60cm) 40W UBVL tubes. The bulb
number was TLK40W/05 or something like that (/05 is the suffix for actinic


24 Temmuz 2008, Perşembe, 6:17 pm tarihinde, Christina Z. Anderson yazmış:
I use Phillips UVBL tubes for all my gum prints. If I was at home I could
look at the bulb number, but they are blue lights, not the deep Jimmy
Hendrix purple but pale blue/lavender.

----- Original Message -----
From: Bjørn Frostad
To: alt-photo-process-l@usask.ca
Sent: Wednesday, July 23, 2008 4:23 PM
Subject: Lightsource for Gum Bichromates

Since the Phillips HPR 125 apparently has been discontinued, I'll have to
for the next best alternative for making my gum-prints.
But - ....I can't seem to find it........
Any ideas?

Bjørn Frostad, Norway