Making two new windows – left and right – to go each side of the existing image of Saint Chad in the middle (who was made some 30 years ago):
Left and right, you could just use unpainted glass.
But this wouldn’t really work, because the light would be uneven.
Horribly uneven …
Do a face on white glass in strong outline only: step back, and the face goes to nothing; strengthen the outline till the forms are quite monstrous – the outline of the nose as broad as the bridge of it – still, at a given distance, it goes to nothing; the expression varies every step back you take. But now, take a matting brush, with a film so thin that it is hardly more than dirty water; put it on the back of the glass (so as not to wash up your outline); badger it flat, so as just to dim the glass less than “ground glass” is dimmed; – and you will find your outline looks almost the same at each distance. It is the pure light that plays tricks, and it will play them through a pinhole.”
Stained Glass Work by C.W. Whall - Chapter VI
(London: John Hogg of Paternoster Row, 1905)
There are various reasons you must consider if your glass will benefit from an undercoat before you start to trace.
Do you remember what these reasons are?
We’ll cover them in just a moment.
And – looking ahead – will it surprise you when I tell you how the undercoat also helps your viewers’ eyes?
Therefore, unless you are painting only for yourself – which might sound luxurious to start with, but actually it’s a mixed blessing because a demanding client can improve your work no end – this is something you definitely must know.