Another Westinghouse H840CK15

[old_tv_nut]

"merely silk screened" doesn't quite describe it.

Zworykin and Morton describe the process in "Television" 2nd Ed. 1954. The description seems to be adapted from a 1951 paper by Barnes and Faulkner, but I believe it is the same as in the 15GP22.

Summary:
Produce the original image for etching the mask by exposing a photographic plate to a fine wire grill twice, with a rotation of 60 degrees between exposures.
Careful processing and copying reproduces a negative optical mask with round dots instead of diamond-shaped.
Expose a thin super-nickel sheet coated with photengraving enamel through the negative.
Wash away the unexposed enamel and etch the exposed metal to form the apertures with sharp feather edges.
Heat this mask and attach to the support frame while hot, so it becomes under tension.
For phosphor patterning, prepare a stencil from the mask:
[One stencil will be used for all three phosphors, with a precision displacement between applications.]
Place a Kodalith plate at the screen position with respect to the mask, and expose with a point-source carbon arc lamp placed at one gun position.
Develop the Kodalith plate.
Sueegee a protective coat of lacquer and wax onto the developed plate.
Coat with photosensitive gelatin emulsion, and expose through the plate onto the emulsion with a carbon arc lamp.
Wash away the unexposed gelatin.
Transfer the wet stencil from the plate to printing mesh and dry it.
Squeegee the phosphor suspension (phosphor powder in ethyl cellulose and amyl alcohol) onto the flat CRT glass screen.
Remove the stencil and clean it.
Allow the CRT screen to dry.
Bake the plate to remove the ethyl cellulose.
Repeat for the other two phosphors, with the stencil precisely positioned.
Bond the phosphors to the plate by misting with potassium silicate solution.
Float a nitrocellulose "blanket" onto the plate and evaporate an aluminum layer onto it.
Finally, bake to remove the nitrocellulose.

The thing to note is that the shadow mask was used as a negative, but with the intermediate stage of producing a silk screen instead of direct deposit of the phosphors.