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

Re: Lightsource for Gum Bichromates



Hi Loris,

You're right! It's even in the documentation pdf Iinked to. They indeed made both versions in 60cm.
Anyway I have a bank with the 20W 05 tubes and another one with 8x 40W CLEO's (UV solarium tubes). The 40 W bank I made with loose lamp fittings and ballasts and costed me a lot more than the 20W bank.

There is a noticable difference in printing time through a silver halide negative of about half a stop in favour of the 40W Cleo tubes. This is NOT the case with diginegs though. Here the difference in printing time is almost neglectable. Similar wavelength seems more important than power when spectral UV blocking is more important than physical blocking by silver particles. And electric wattage is not always directly related to actinic power I think. The discontinued HPR125, mercury vapour lamp is a good example - a lot of the 125 is warming the air instead of printing.

kees




On 25 jul 2008, at 10:17, Loris Medici wrote:

Hi Kees,

The tubes I use (TL'K 40W) are indeed 40W, and they're definitely 60cm
long and their diameter is definitely 38mm. I built the exposure unit
myself (pretty much as you describe) so I'm pretty sure about the specs.
The store I purchased them also was stocking the 20W version but I opted
for the considerably more powerful 40W version.

Bjorn, the average exposure time for my gum prints is between 3 - 5
minutes per layer (w/ 5% ammonium dichromate) -> far from being awfully
long ;) You're comparing apples to oranges I think... (The 125W you
mention is for Photoflood type lightsource I guess - right?)

Regards,
Loris.


25 Temmuz 2008, Cuma, 11:02 am tarihinde, Kees Brandenburg yazmış:
Hello Bjørn and others,

Loris is right on the wavelenght but not on the 40W. The 60cm 05
tubes are 20W and 38mm diameter, at least mine are. That fits them
nicely in cheap harwarestore 60cm 20W fittings.

Here's the (old) pdf with product information:
http://polychrome.nl/file_download/18/
9nice printing unit

If you skrew 8 to 10 cheap 60cm 20W fittings, the shallowest you can
get, close together on a piece of plywood you get a 50x60 UV unit.
Attach plywood back and sides of about 20 cm height for a self
standing UV unit . You can slide your printing frame under it from the
front.

The Philips 05 is now discontinued, the 03 still exists but is a 40W
60cm. There is a new series for (repro)graphic use.
This one (Actinic BL TL 20W/10 SLV) could be a replacement for the
05: http://tinyurl.com/5trwnm
There's also the Blacklight Blue (TL 20W BLB SLV):
http://tinyurl.com/666hdq

kees




On 25 jul 2008, at 08:00, Loris Medici wrote:

Erich, something must be wrong (either on my part, or yours), since
the
technical specs I got from Philips Turkey indicates that the peak is
around 360 - 365 nm., and therefore making the /05 series perfect
for most
alt processes.

Regards,
Loris.


24 Temmuz 2008, Per�embe, 9:38 pm tarihinde, Erich Camerling
yazmı�:
Bjørn,
Look in the archive.
Date: 20th of March 2002,Re:Light source for big prints.
correction:color 03 peak is 365 nm
          color 05 peak is 420 nm
          lenght must be length
addition  :peak CLEO is 350 nm

Erich Camerling


----- 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 go for the next best alternative for making my gum-prints.
But - ....I can't seem to find it........
Any ideas?


Bjørn Frostad, Norway



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