Here’s a link to a YouTube video about the manufacturing of CRT of color picture tube. Some audio near the end is missing but than returns at the end. No date that I could fine but since it includes rectangular CRT’s I’m guess it’s vintage is very early sixties. Enjoy

https://youtu.be/7IrSLPVkxCo

I see Penthode already has this as a thread. Since this is a duplicate any moderator feel free to delete this duplicate.