Question Time

An email from Tom M.

“My question concerns both tools and technique.

It seems you usually paint on the light table.

So how do you ensure continuity of technique, with adjacent panels being neither too dark nor too light, without waxing up your glass?”

Tom is right.

We usually paint on the light table

Yes, we usually work flat as here with silver stain:


There are key stages however when we attach the many bits of coloured glass to big sheets of 6 mm strengthened glass.

For instance, we’ve finished cutting and want to see how the unpainted colours work together:

Or near the end of painting, we want to see how legible our lines and shadows are:

These are times when we want to put as much glass as possible in a similar light to how it will be seen.

Other times – it’s just the way we work, the way which works for us – we use the light table to go as far as we can.

And Tom’s question is:

Working on the light table, what keeps us consistent from one piece to the next, from one panel to the next?

Ingredient number #1: imagination

We’ll begin with “imagination” because, when I started learning, I mistakenly sought proof.

A guarantee.

I wanted to be sure.

Which now I understand just isn’t possible.

And “imagination” draws attention to this fact.

Because waxed up or flat, we’re always forced to make a guess:

  1. The window isn’t leaded.
  2. The quality of light is different.
  3. The angle also.

Not to mention how some projects will be too big to display them as they’ll eventually be seen.

That’s why, whether flat or vertical, in natural light or artificial, it’s always just a test.

Only your finished, fitted piece is the real performance.

You cannot know. You must imagine.

And if this seems bleak, just be assured how imagining the outcome is not the same as guessing: there’s a lot you can do to feed your imagination and give it foresight.

For instance:

Ingredient number #2: test pieces

So for instance, before we choose the colours and cut the glass, we might paint 5 or 50 test pieces which reveal the effect of layering techniques in different ways.

E.g. undercoat, light trace, flood, strengthen, highlight, fire, enamel, and fire again.

Or: light trace, wash, reinstate, strengthen, highlight, glycol shadows, glycol details, fire, stain and fire again.

And so on.

At the end of this Beauty Show, we’ll pick one or several of our test pieces to go forward to the next round.

So now we’ll start to have a sense of purpose.

Yes, it’s true: before we started testing, our imagination was too blind for comfort.

Which may surprise you since people often write and ask us, “How do I paint a face like this?” – and the amazing thing is, they believe we already know the answer.

And I sense they get frustrated when I write back, “It might be this way, or it might be this way, or it might be this way, or …”


Yes, because they say, “Yes but which way?!?!?” – and all I can reply is, “I don’t know, I haven’t done my 5 or 50 tests …”

Till we’ve done our 5 or 50 tests, our imagination is blind.

And I don’t want you to think it’s inexperience if you discover it’s the same for you.

Ingredient number #3: prototypes

But even with these test pieces we trust, we still don’t know enough to risk cutting 20 sheets of glass:

That’s where a prototype can help.

That is, a painted, fired, leaded, cemented, polished section of a window.

We make prototypes if the window’s big or its light conditions are peculiar.

This way we can take the prototype to our client’s building and look at it in situ. We can check a purple or a blue or red etc. is reacting as we believed it would.

Or that our shadows and highlights are strong enough.

But just as when you wax your glass against an easel to see it vertically in daylight, so also with the prototype: it’s always just a test.

The responsibility is still ours to interpret the result.

We must still use our imagination and experience.

Again we must embrace the risk of failure here: it’s not possible to know.

This risk might stop us sleeping well.

But the sense of danger also helps us find the strength to concentrate for many months.

Ingredient number #4: batch-processing

Now we cut the glass.

And like you saw earlier, we’ll probably attach it all unpainted to a sheet of strengthened glass to verify our choice of colour.

All being well – it never is though: we always replace this piece and that – next comes painting.

The first method we use to keep everything consistent is batch-processing.

So we undercoat a lot of glass at once, say 30 pieces.

Then copy-trace them all:

Then flood and strengthen them etc.

This means you focus on one brush, one consistency of paint, one sequence of actions: far easier than jumping around from undercoat, to trace, to flood, and back to wash again, endlessly repeated.

Of course, by consistently repeating a process, we could consistently go wrong.

I admit, the risk is there.

And nothing will make it go away.

Same answer as before: there is no proof, which makes us pay attention.

Ingredient number #5: the companion piece

But you don’t like mistakes and nor do we.

That’s why, before we start each stage – e.g. before we move from tracing to strengthening – we paint a “companion piece”:

  1. It helps us confirm our paint is the right consistency and density of pigment.
  2. It validates our choice of brush.
  3. And it gives us time to practise the pace this particular technique requires e.g. flooding is faster than tracing.

This means, right at the start, we get our undercoat the way we want it – and just repeat.

Then we get our trace-lines as dark or light as they should be – and just repeat.

It’s one of those situations where, by saying to yourself “It doesn’t matter if my companion piece goes wrong”, you usually paint it right, and then you’re confident enough to do the other 29.

Not just “paint” – also highlights.

Here’s a short video where you see “softening” the companion piece, then “softening” the main piece.

It all goes well – thanks to the opportunity you have of practising beforehand:

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Ingredient number #1 again: imagination

But another point to bear in mind is: don’t you feel that some variation is good and human?

After all, this isn’t printing.

Yes, you might trace 30 pieces one after the other (and then move on to flooding 30 pieces) all in the name of efficiency.

But yet it’s not mechanical.

Which means that sometimes you compare your glass with your test piece and notice a darkening of the lines and say: “This is fine – yes: my imagination tells me this will be fine”.

And anyway the glass is often different

Now I don’t know which country you’re in, but here in England we can still buy good quantities of antique mouth-blown glass.

And this glass varies in density of colour from one side to another.

So the glass itself brings variation, which we don’t try to conquer.

Rather, we value the way neighbouring pieces of the ‘same’ blue will differ slightly from one another, depending on where we cut them in the sheet.

For us, chance differences like this are fine.

We’re relaxed about them.

And the reason we’re relaxed is, we know how there are places we’re in charge.

As in life, so with glass: control what you can and relax about the rest.

That’s what works for us. That’s what we do to get the continuity we want from one panel to the next.

And that’s enough from me.
If you have methods you want to share or questions you wish to ask, please use the box below.

P.S. Our foundation course Illuminate will soon open for the final time this year. If you want to join us for this training and get confident with the key techniques, then say so here.

Have a question? Ask it here!

Prince Neli -

Great ideas for glass painters. I do same. Thanks for the work. Stay creative!

Sister Marie Tatina, Oblate OSB -

Stephen your answer is exactly what is required for success in our glass world. You're right there are no guarantees or simple formulas. In our studios we cant replicate the ambient light we encounter especially in a church. There are so many variables to consider but imagination and the "mental road map" I refer to are key. I too prep and paint adjoining pieces at the same time. Especially background mats. There was one job I did for my former monastery where I matted all of the background pieces at the same time not cutting them to the finished size. I made allowances for the different sizes and after firing as I assembled or laid out for leading I wheeled by mobile cutting light box next to the window. I removed each cut paper cut pattern from the window. I traced and cut and placed it on the window to be leaded. That takes time but that way I can control the results. Like anything else in life you've got to practice, imagine, (& I pray) and then don't be afraid....Go do it. A long time ago when I was newer at painting and my imagination not yet developed, I installed 12 windows each containing a different saint. I just was not happy with the face of St. Anne so I went back to the studio realizing the light behind that window was slightly different. I cut a new piece of glass and redid the face. I was so much happier with the results. I went back to the church removed the window and did a proper replacement of the previous face. I never take short cuts for over the years of restoration I've seen garbage and poor workmanship has done to windows.

Sister Marie Tatina, Oblate OSB -

An addition to my previous reply. In order to be consistent with results I make my original drawing with every detail that I want my finished window to contain. Even if I'm going to silk screen some of the borders I draw everything out. I mark the grain direction, show the lead sizes usually with red or another color. I indicate lights and darks for shading etc. I don't wax up except rarely for a special project. I don't need to do so, for my mental road map for everything is on this drawing. I then make a copy of this drawing using the usual carbon paper. Only this time, since this is my building pattern I just make necessary reference marks. Then using 3 prong glass scissors I cut out my original drawing which I use to draw my glass pieces before painting. All of this takes time but in the long run I have less glass waste, I control the grain and thickness and shades. Actually it makes painting a much more relaxed event and leading goes a lot quicker. I actually draw and shade the faces, hands etc on the original as I want them to be after painting. I want my painting time to be enjoyable and successful. In today's I want it now world I caution people who ask me about glass asa way of living. If you want to make a quick million or have an easy carefree job don't do glass. For me the reward for all of the long hours and hard work is NOT the money it's the finished job. To stand in a church and look at the completion of that work is satisfying but also very humbling. I'm barely 5'tall now that my legs are crippled and to stand before a 34' tall finished window is awesome. I feel kind of small and I look up and say "Thank you, Lord"

Caroline Perrington -

Wow, I have so enjoyed reading your comments, Sister Marie, thanks for sharing. And your instructions Stephen are always generous and insightful.