Two summers ago I made some large cyanotypes as follows. Covered the windows
and plugged holes in my garage so it was dark enough. Attached large sheets of
paper to plywood with masking tape. Under a small wattage (15 watt) bulb
coated useing a large foam brush. Let dry in dark. Under a small red party
bulb, arranged various objects on surface (in Rayograph fashion). I remember
using various weeds and leaves etc. Opened garage door and had my wife help me
carry the whole mess outside to a pair of sawhorses in the driveway in the sun
for exposure. Exposure was fairly rapid. After exposure, it was returned to
the garage. The print was removed from the plywood a developed in the bathtub.
Hung up to dry in the laundry room.
I have heard of people using a garden hose to develop large cyanotypes.
Terry has mentioned using a mercury vapor bulb (like a street light?)
overhead in a dark studio and making an "overnight" exposure.
Those long wallpaper paste trays you can find in hardware stores can also be
used. (Does anyone remember developing ortho roll film in a tray?) If you
used the trays you could also do large VDBs if you could afford the silver
nitrate. ;-)
Bob Schramm