I've been reading into how CRTs were assembled and how they work, but I can't seem to find any concise information behind how the coloured phosphors inside the inner glass tube were applied. There is a bit of a write-up here that explains some techniques but it's hard to visualise without having a background in CRT manufacturing.
Are there any resources available that show this process of the red, green and blue phosphors being applied to the inside glass?
A CRT consists of three parts
Phosphors are applied to the inside of the screen before the screen and funnel are joined.
The main issue with a colour CRT is getting the phosphor dots to line up with the electron beams that will be sent through the mask. This was originally a triad-type shadowmask, but was later improved to a slotmask or aperture grille. To this end they are applied photolithographically, using the mask itself to define the exposure.
Photolithography consists of applying a thin film of active ingredient, mixed with some sort of photosensitive binder, to the inside of the screen. This is then selectively cured with an appropriately patterned light source.
For each colour phosphor, first a thin film of phosphor+binder is applied to the screen, and dried. Then the mask is fitted temporarily, and the screen is exposed using a point light source in the position of the electron gun that will be illuminating that particular colour. The light hardens the binder, and then all of the non-exposed phosphor is removed, with a rinse or an etch depending on the chemistries used, leaving the hardened dots in the correct positions. This is repeated for the other two colours. A final application of a light-proof layer may be added to prevent light bleeding between the phosphor dots.
Now the mask is permanently attached to the screen. Then it is fitted to the funnel, then the electron gun assembly added. Finally the tube is purged, evacuated and sealed.
