The stained glass easel; why?

In the process of making stained glass there are two stages where the glass is easeled up against the daylight. First, when selecting glass, then later, when glasspainting. Easeling glass is time-consuming and thus expensive, so why do this?

Here’s my current work for All Saints Chapel at Carroll College in Helena Montana. Note how the opalescent glasses change at night/dusk. This is an effect that can only be estimated, whether on light table or easel, because my north-facing easel does not precisely mimic the light in Montana. The easel does, however, take out a lot of the guesswork.

 

 

Check a few older posts if you want to find out more about how and why glass is fixed to the easel, and watch the embedded video links. Stage one, selecting glass for colour, transparency/opacity and texture the English way, by fixing it to the clear glass easel plate with Plasticene; about choosing colour for a landscape window with figures; using beeswax and rosin (which fires off later in the kiln) in the process of  waxing up (fixing painted, fired  glass onto the easel for further layers of glasspaint); and details of a specific wet-matte technique that may be achieved with my https://coombscriddle.wordpress.com/2015/06/22/spreading-the-word-worldwide/proprietory propylene glycol mixture.