Hello again. Thanks for coming over – always, the extra time you put in … it will serve you well.
So, the benefits of painting an undercoat before you trace …
First, the undercoat gives you a lovely (slightly rough) surface on which to trace. It actually improves your brush-control.
Second, it helps you build up depth of colour, layer by layer, in a steady way. Indeed, dark paint can be difficult to control, but now you don’t need to risk overloading your brush with dark paint, because the undercoat itself gives body and depth to the lines you subsequently trace on top of it.
Third, the undercoat protects your glass from airborne grease; it keeps it clean (bare glass gets dirty, and you can’t paint on dirty glass).
Fourth, it reminds you to handle the glass carefully at all times so as not to make it dirty or damage the work you’ve done already.
And fifth – after you’ve finished tracing and shading, you can take a stick or scrub and make highlights by cutting through the undercoat to the bare glass underneath. Do you see how astonishing this is? Most books say to trace, then fire, then apply a matt in which you make your highlights, then fire a second time. But with an undercoat, you fire once.
Exactly: paint better, fire less.
Now I’ll tell you one more astonishing thing.
Most books say to trace and fire, then do your shading afterwards, and fire again. Yes? Most books say you need several firings to trace and shade.
But listen to me here. And listen carefully because it’s important.
“Trace then fire; shade then fire; and so forth …” This is not how the ancient glass painters did their work. Firing was far more complicated, hazardous and expensive than it is for you or me today. Which means the ancients didn’t fire their glass more times than they needed to. And here’s the point: I know for a fact it was by means of the undercoat the ancients could trace and shade and do all their painting in just one firing.
Why is this important?
Just look at ancient painted glass.
Isn’t it beautiful?
And wouldn’t you like to learn to paint that well?
Paint better, fire less – yes, you need a lump of glass paint (not a teaspoonful), and after that, you need … the … undercoat!
P.S. Next time I’ll tell you the technique.
P.P.S. With all of this, don’t wait for me to tell you everything you want to know: have a go. Your own experiments will give birth to useful questions in your mind.