> I acquired a "platemaker" recently, but haven't had a chance to figure out
> how it works, if it works, and/or what to do with it. What I have is a
> machine originally designed for making blueprint copies. Unfortunately, I
> don't remember the brand name or model. It looks like a roller mechanism
> takes the copy and sensitized paper past a lamp, and then runs the exposed
> paper through a developing solution (ammonia?).
It used to be that when architects made blueprints they really were
cyanotypes. Local history tells us that the original Northern Pacific
Railroad's headquarters building in Tacoma, Washington had apparatus on
the roof which was precisely for that purpose -- huge cyanotype prints of
railroad project plans. Old photographs show it. I would love to see
some of the prints, but never have. Supposedly, there was a very large
glass drum which turned for solar exposures. If you have ever been to
Tacoma in the winter time, you have to wonder what those people were
thinking about. Exposures must have been forever.
The name "blueprint" stuck, but the diazo process is not the same. One
problem with the process is that instead of the dye compound being formed
through the action of uv light, the light destroys or prevents formation
of the dye. Hence, impermanent.
As I understand, the process began to supplant cyanotype in the 1920's.
Too bad the machines aren't more useful for our purposes (don't know if
you can recover the light) because there are lots of them around.
"Ozalid" is a common manufacturer.
Larry Bullis