From: Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Date: 05/18/01-06:10:32 AM Z
nze christian wrote:
> ...I am interesting in making some 2 squares meters platinum palladium print..
> I am looking for info about paper or tissue (silk or others)of this size and
> also negative.
> I will do my neg via both way silver neg and computer one.
>
> I will first make cyanotype test but I will be pleased to know if any one
> ever do some.
Cyanotype may work different from Pt/Pd on various materials.
Silk will not work well for Pt/Pd. (for fabric check in my guide under
substrates.)
That large of a negative (in both directions) may have to be a composite
(several negatives trimmed and placed side by side). A good rotary
trimmer should make a clean cut. I have done this on some folding
screens (several 8x10s) with a good clean butt joint needing very little
touch up (spotting).
When contact printing such a large coating, it will be best to custom
build a printing frame. For the back build a slightly larger than 2x2
meter structure with 2x4 inch lumber studs 8 inches on center to two end
pieces and with blocks every 8 inches similar to a small wall. Then
attach 3/4 inch plywood glued and screwed to all studs. Note that the
plywood must be larger in length and width than the wood structure and
the screws flush flat head. The plywood will have to be in several
sections as the standard size is usually less than 2 meters. It would
be best to have the plywood tongue and grooved or attach extra pieces of
plywood to the back at the joints so as to keep the front surface
flush. Smooth and flush is important for good contact, sand carefully
if necessary.
Over the wood place a black vinyl sheet, then the coated substrate and
negative(s), then a THICK glass, and fasten secure with many spring
clamps around the perimeter. Do not use any tape to hold the negatives
as this will prevent good contact. If the glass is too thin, the center
of the glass will loose contact as the clamps are applied. Something
that may help prevent this is to add a perimeter of vinyl/paper/negative
so as to maintain the same thickness where clamped.
If using the sun, it would also be a good idea to attach a set of wheels
to one side so as to roll around and attach two support sticks to the
ends of the side opposite the wheels that can be adjusted to aim (angle)
the frame at the sun. A dowel or pencil held perpendicular to the front
of the glass will show no shadow when aimed at the sun. The exposure
should not be long enough to have concern about moving the frame, but if
it is, it is simple to adjust position manually.
I guess I have considered doing large prints myself. Also, one nice
thin about fabric is that it can be loosely folded up and processed in
buckets. Also do take the time to make small test prints using the
frame and all as the cost of a print should be substantial. (I have
achieved fairly good consistency with the sun between 10am and 2pm.) If
using artificial lamps, uniformity across that large an area can be a
challenge.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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