The heat from a 5000 watt mercury lamp is basically not a factor on a short
exposure. I would imagine (even though I haven't contact printed yet), that
your exposures would be under a minute with a 5k lamp. I have been in the
silk screen industry for 20 years, the shop I work in now has a 5k unit. Our
exposures are from 2 minutes up. The distance is approximately 4 feet to the
vertical table. Back in the old days we used a carbon arc lamp, love that
old ozone smell!!!
 There are many companies making fast emulsions. The problem is the type.
There are diazo and photopolymer emulsions. The latter needs a different
spectrum lamp or it will never expose.
The cameras you mentioned?? We use Barco laser created positives on acetate,
taped to a screen and exposed in the vacuum frame.
 I tried coating some paper at work with emulsion and exposing it. The
screen emulsion doesn't work unless the substrate is porous. Uncoated paper
worked the best. I was using a 135 line Offset negative for the contact
printing.... Meant to try more but...................
----- Original Message -----
From: "John Cremati" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, February 02, 2003 9:30 AM
Subject: Re: [Cameramakers] Light source for enlarging onto
platinum-paladium and Kodak Azo papers


>
> Hi Donald ,
>        I also  know in the silk screen industry that they have projection
> systems where they eliminate the large negatives used to contact print ,
> and enlarge right on the coated silk screen.......I have seen just one of
> these cameras in a old silk screen catalog but have never tried to
research
> it any further.. The silk screen process requires a great deal of UV light
> as well .. I know that Ulano ( a mfg of silk screen emulsions )  sell a
> faster emulsion for the sole  purpose of silk screen projection systems
> ....I do not know if the lenses used on these cameras are quartz or EL
> Nikkors... I have heard ( not verified ) that these cameras sell for
$50,000
> ..
>        I have several high output UV lights intended for the silk screen
> industry.... . One at 1000 watts, 2000watts, 5000 watts and then the
> 10,500watt pulsed xenon ... I was intending to experiment on temperatures
at
> the film plane as well as the enlargement plane  once I got the camera set
> up as I feel this is going to be my biggest obstacle ..
>           The process I am most interested in is Carbon Printing which I
> believe possibly exceeds  platinum as the most beautiful process there is
> ( only does not have the expense of platinum plus offers a noticeable
high
> relief quality that is found in no other process)The Fresson Process ,
> although secret , is believed to be a  form of a carbon  printing
> process.....  The problem with Carbon is that it will be very temperature
> sensitive due to the large amount of gelatin used ...  .  I was thinking
of
> rigging   a series of water cooled tubing to the vacuum frame on the
> enlarger and piping it to a  photographic chiller that I have.. ...
Another
> idea is that   I would also wash the vacuum frame with the  breeze of a
> small air conditioner.. And refrigerate the blower air that cools the film
> in the light head...
>     I will photograph the light head  on the camera and send pictures off
> list  if you want me to ..
> Regards,
> John Cremati
>
>
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