From: Richard Sullivan FRPS (richsul@earthlink.net)
Date: 06/19/01-12:09:17 PM Z
Fluorescents are acceptable for platinum and palladium type prints. However
it may not be the cheapest or the easiest way to go. For other print
processes like gum, I think a better way to go is with metal halide.
If you are building a fluorescent unit you should use solid state ballasts
and if actinic or aquarium bulbs are used, Icecap ballasts should be used.
This can be expensive! I think they start at around $150.00 per ballast and
you will need 4 of them to start plus bulbs.
An ordinary metal halide luminaire works fine for alt printing. A little
slower than the units made for commercial UV printing but at a fraction of
the cost. It is also semi-point source, a benefit, and we'll get to that in
a minute.
What's a luminaire? it is one of those big lights you see at in the new
supermarkets or Home Depot.
The MH (metal halide) units are big and do require some extra room. The
space is mostly up, meaning you need some distance between the light and
the print. FL (fluorescent) units don't use much vertical space.
MH units are more efficient than FL units per light output per watt. That's
why they're used in big buildings now instead of FL's. Serious marine
aquarium folks are all going with mini metal halide units -- i think they
are similar to the head lamps in the new luxury cars!
MH units safe as the UV produced is a spike just after the 350 nm glass
cut-off point. They're bright so direct looking at is frowned upon! You
don't stare at the sun either!
How to make:
Buy a luminaire unit from any wholesale electrical supplier. The 1000 watt
units are the most economical in the long run. Buy a bulb (lamp) reflector
and ballast. the ballast is the big thing the bulb screws into.
It's a two hammer project. Buy a ballast that is a 120 volt. They make a
multi-tap unit which is fine also. The wiring is simple but if it is a
mystery to you have your wholesale dealer show you how.
The bulb is a big monster and looks dangerous. It is not under pressure and
the glass envelope is there to filter out the harmful UV light.
They come with varying size reflectors. Most have a standard one which is
fine. If you are only printing 8x10 then get a small one as it will
concentrate the light. A large reflector on a 100 watt unit will cover
16x16 quite nicely.
You will need to figure out how to suspend the unit above the print. You
can hang it on a chain assembly of some sort. You can build a box to hold
it with a door to slip the print frame into. The only thing you need to do
is suspend it somehow above the print. The luminaire will weigh about 35
lbs so you might need help if not a body builder. You will probably want to
put some sort of shield around the unit to keep people from staring at the
lights.
If you are printing Ziatypes or enclosing the unit in a box you will
probably want to have some sort of fan to keep the frame cool. My first
unit I used a window fan from Target. Worked fine.
You can cover really big prints by suspending it higher. Of course less
light per unit so longer print times.
A 1000 watt unit will print at about 2 to 3 stops faster than a 40 inch FL
F40Bl unit. Only 3 wires to hook up. It will cost, including bulb, approx
300 dollars. Cheaper from some sources. Big city folks may shop and find
bargains wrecking companies may have used units for sale.
Screw on the bulb tightly. it is not as fragile as it looks and I had
problems with some of my first units because it arced inside the socket
because I did not screw it in tight enough.
Downside:
They don't turn on and off quickly so they are best used for attended
printing. Set a timer and when it buzzes remove the print. If you shit it
down it will take 4 to 6 mins to restart. Most serious printers are doing
attended printing. Once in a while I have a dense neg to print and I'll put
it on a timer and then leave the studio and go home. I process the print in
the morning.
In actuality a 1000 watt unit uses about 2/3's the power of a small space
heater so leaving it on is not as bad as it looks. They produce an awesome
amount of light for the power used.
There is a picture of my 42 x 54 inch print frame and a 1000 watt light at:
http://www.bostick-sullivan.com/dicksullivanPrint.htm
That's me 60 lbs ago!
I am putting up a 400 watt unit on either side of the big unit to get a bit
more coverage. The unit just sits on top of the two 2x6's with the bulb
going down between the boards. I've tied it on with straps being an old
earthquake country guy I still haven't got used to things staying put
overnight.
The whole point of this ramble is that the standard MH units work fine. The
installation requires a bit of ingenuity to fit into your environment.
I printed gum for many years using FL units. I did a couple of sample runs
using the MH and was astounded at the life in the prints.
Here's my take on point versus flat lighting (FL).
If you suspend your hand only an inch away from the print surface under a
FL unit you get a blurred hazy indistinct shadow. Not quite even a shadow.
Under a MH unit your hand makes a sharp distinct outline. If you imagine
your negative suspended one inch from the printing surface you can see how
you'd get no image, just a blur on the paper. Under a point MH if you hold
a neg up an inch away you can actually make out an image. No one prints
their negs (except in an enlarger) 1 inch away. But I think the theory hold
true all the way down to the paper and then some. If you don't get tight
contact between paper and neg under a FL unit you get a distinct blur.
under MH you don't as the neg is still imaging at 1/64 of an inch away from
the paper. Gum has thickness and film has thickness so none of the parts of
the neg image are in perfect contact with the paper and thus there is some
fuzziness to the image. Imperceptable maybe, but then maybe not. Pt
printing is a flat surface not a thick surface like gum so it is not as
affected by the flat versus point source light phenomenon.
Enough.
Any questions?
--Dick Sullivan
At 11:21 AM 6/19/2001 -0700, you wrote:
>Jeffrey wrote:
> >
> > Please do not be confused.
> >
> > Keep in mind that the bulbs labeled with a BL are not the black lights
> > referenced. Dick refers to the dark black lights commonly used in head
> > shops and popular in the '60s to illuminate fluorescent posters and the
> > like. The BL lamps produce a very bright white looking light that
> > contains a lot of UV (ultra violet light).
>
>Now I'm really confused. Should you buy black lights, like in head shops,
>or something else called BL? In Dick's book he says "BL (Black Light)" as
>if they are synonymous.
>
> >
> > Aquarium and plant lights give off a lot of UV, but the BL lamps are
> > usually available in much higher outputs. To compare the output of
> > typical fluorescent lamps, divide the listed wattage by the listed
> > length. It is the wattage per area that will represent the flux (light
> > intensity). Since the width (diameter) of the lamp is insignificant
> > relative to the length, the length can be used as area.
>
>This makes sense.
>
>--shannon
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