From: Judy Seigel (jseigel@panix.com)
Date: 05/18/01-10:46:56 AM Z
On Fri, 18 May 2001, Jeffrey D. Mathias wrote:
> 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
Reading these instructions for custom building a contact frame for that
size, I wonder if it's better, or even as good as simply laying glass on
glass. Last P-F showed Kent Rush making a giant cyanotype with a patio
door as top glass (on cart on wheels, rolled out of garage into sun).
Upcoming P-F shows a couple of other strategies for large prints without
carpentry on scale of Metropolitan Opera House -- for instance my own
glass on glass -- works very well, tho only about 1 meter by 1 meter.
In any event, short of heavy carpentry on this order, the best contact
(IME) is gained by having weights right over the image, not clamps.
Glass on glass facing down (suspended over lights, shown P-F #6) permits
that. It sounds (from here) like just opening and closing such big device
would be major act of muscle, even were it to appear fully built in yr
xmas stocking.
Judy
> 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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