An interesting contribution from an old RCA publication (once ensconced in a Westinghouse research facility library) adds insight to early television color picture tubes.
Here is an authentic picture of the developmental RCA 19-inch tricolor kinescope.
Officially labeled the C-73629 by RCA, it was never produced. The larger phosphor dot screen probably resulted in even greater manufacturing challenges than the 15GP22. During the evacuation phase of the process, heat could dissipate from the plate primarily by radiation, resulting in a propensity to crack because of great temperature gradients within the assembly as it gained and lost heat.
This C-73629 photo is from proceedings of the "Symposium On RCA Developmental Large-Picture (19") Tricolor Kinescope" dated January 21, 1954. Thanks to Steve Restelli, Webmaster, HistoryTV.net for this important photographic contribution.
Steve notes that "this book appears to have been Westinghouse's Library copy and was put together for licensees moving from the 15" version to the new 19" color tube. I have the card of the engineers who signed out this book in the 60's and the last date is from 1968. This was a well used reference book."