[alt-photo] Re: Alternative Exposure Unit (no pun intended)

[Marek Matusz]

I really could not believe that gum can be exposed with light containing no UV component, so I tried. My exposure was LED light, phillips 3500K (this is on the yellow side). I recently instaleed a few of these on my track. The are 8LED's in a PAR 30 enclosure. DIstance from a single lamp was 14 inches. 6 minute exposure gave density of the gum print equivalent to 1 minute of the BL unit. Phillips explicitly states that the LED's do not emit any UV. It seems that a cooler light (6500K or so) would emit more blue component and make exposures shortes.
WOW, this is impressive.

Marek 
> From: zphoto at montana.net
> Date: Thu, 11 Mar 2010 15:14:53 -0700
> To: alt-photo-process-list at lists.altphotolist.org
> Subject: [alt-photo] Re: Alternative Exposure Unit (no pun intended)
> 
> Wow, Carole, GREAT idea! Thanks
> Chris
> 
> Christina Z. Anderson
> christinaZanderson.com
> 
> On Mar 11, 2010, at 2:58 PM, Gumprint wrote:
> 
> > Christine, Group:
> > 
> > I had been using a custom made BLB set up with 8-24" bulbs for over 15
> > years. The bulbs are very expensive to replace and my exposures were 90
> > seconds to 7 minutes. Last month Barry Schmetter brought in a Fotodiox unit
> > for me to use for a gumprint demo at the Large Format and Alternative
> > Photography Gathering (Metro Wash DC). Using my gum/pigment mix 1:1 with 15%
> > ammonium dichromate sensitizer I was able to reduce my first emulsion from 7
> > minutes to 70 seconds. It was perfect. The second emulsion was correct in 30
> > seconds. This unit has completely changed the way I print.
> > 
> > http://www.fotodiox.com/catalog/product_info.php?products_id=78 fitted it
> > with 16 Bright Effects (swirly type; 26 watts daylight or 6000K from Lowes).
> > The unit is intended to sit on a lighting tripod but I added a clamp and
> > attach it to a heavily loaded bookcase. The unit is currently going for $135
> > + shipping. Add $30 for a clamp if you can't rig up something, a builder
> > pack of the bulbs, and you have a very fast, compact, and portable exposure
> > device.
> > 
> > Best,
> > Carole
> > 
> > 
> > 
> > On Thu, Mar 11, 2010 at 4:18 PM, Christina Anderson <zphoto at montana.net>wrote:
> > 
> >> Has anyone bought one of these and used for alt or gum?
> >> And what is the best URL for a plan to build one's own? Apparently the
> >> plan I hand out to students out of Nadeau's is incomplete, but since I am a
> >> building failure, I can't explain why it is incomplete. I wouldn't know a
> >> magnetic ballast from a martini frankly.
> >> Chris
> >> 
> >> 
> >> http://www.silkscreeningsupplies.com/site/799934/product/RXP2024
> >> 
> >> Christina Z. Anderson
> >> christinaZanderson.com
> >> 
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