UG-1 in Church Window?

[Kai]

On vacation in France I took a UV photo of a church window (approx. 360-400 nm, color enhanced). For comparison, I took a VIS image with my smartphone.
Much is not surprising. Only the visually achromatic, dark glasses unexpectedly show quite good UV transmission. One glass seems to let through shorter-wave light and appears somewhat yellowish, the other dark glass only lets long-wave UV light through.
Judging by the motifs of the other pictures (not shown here), the pictures are 80-100 years old.
 

Does anyone here know anything about church windows/ stained glass?
 

 

UV picture: 2022-07-06, 13-26-34, Canon 6D-FS, ZWB2 plus TSN575, Canon EF 2.8 28 mm, f 4.0, 1-8 s, 3200 ASA, DxO development

[Nate]

Very interesting for sure. At first glance, it seems the lighter glass goes dark, and the darker glass goes lighter, and the white stays white. 

[Dmitry]

Found this wiki article

https://en.wikipedia.org/wiki/Stained_glass

[Kai]

1 hour ago, Dmitry said:

Found this wiki article

https://en.wikipedia.org/wiki/Stained_glass

Thank you for the advice, Dmitry! The English article is much more detailed than the German one.

The notes "The most common method of adding the black linear painting necessary to define stained glass images is the use of what is variously called "glass paint", "vitreous paint", or "grisaille paint". This was applied as a mixture of powdered glass, iron or rust filings to give a black colour, clay, and oil, vinegar or water for a brushable texture, with a binder such as gum arabic." are interesting. You could start there...

[colinbm]

The stained glass windows are fantastic & a very technical history back into the dark ages.
These people were very clever.
'Structural Colour' is a name for it.
On example that I have read is the rich colour of red, it is made from nano particles of a particular size of gold powder.
 

[OlDoinyo]

FWIW, I posted this last year.