16 May
2005
16 May
'05
12:21 p.m.
On Sun, 15 May 2005, Billy Pettit wrote:
3M used to make a product that was a thin alunimum
with a photo emulsion on
it. It worked like a blue print. Make your master on vellim, print it using
a blue print machine and develop it with ammonia.
THat reminded me of stuff I've used from 3M, it was called
COLORKEY, then COLORKEY II.
The old stuff (1970's) was great -- adhesive aluminum, plastic,
clear, non-adhesives, etc in various simple colors, with a
light-sensitive layer in a contrasting color; white on red, black
on aluminum, black on clear, white on blue, etc.
We used it for PCB masks and front panels both.
Exposures with 100% contrast negative, photoflood light about 3?
minutes, a fairly non-toxic developer w/cotton ball. Rinse dry
use. Cheap too!
About 1996 I hunted it down again, was still around as COLORKEY
II, but I could only find clear substrate.
The litho industry used a lot of the clear stuff, I don't know
what happened to the rest.