Stained Glass Painting: “What if I Make a Mistake …?”

A question from the postbag

A colleague from the Netherlands asks us something really useful:

As a novice, I have a burning question.

Say I experiment with your technique: so I paint an undercoat and then copy-trace the main lines from the design.

Now what if I make a mistake during tracing. What is the best procedure for correcting this mistake without ruining the work I’ve already done?”

This is such an excellent question, we’ll approach the answer from several different directions.

First, though, let’s step back a bit and give some context to the question.

All your tracing and shading, front and back, in a single firing

Yes, we discuss and demonstrate this a lot. Not because it’s the only way to paint stained glass. Rather because when you master this technique, many other techniques are easy by comparison.

And also because so many people have been told, “It’s impossible!”.

Well it isn’t.

Here’s what we mean:

  1. Paint an undercoat which primes the surface of the glass
  2. With the design on top of the glass, lightly trace the main lines
  3. With the design on one side where you can see it, strengthen the main lines as needed
  4. When these are dry, cover the whole surface of the glass with a light overcoat of paint
  5. While this overcoat is wet, take your badger blender and turn these precise lines into blurred lines and shadows
  6. Now with your tracing brush again, reinstate precise lines where needed and also add fine details
  7. Make highlights as needed
  8. Paint on the back as needed
  9. Use oil-based paint on the front as needed
  10. Make new highlights as needed
  11. Fire your glass

So right until step 9, you’re using water-based glass paint.

And the glass is only fired once.


As I mentioned earlier, if you learn this approach, you’ll find most other things easy by comparison.

More to the point, you’ll do those other things with greater confidence and skill.

So when you decide that a particular design doesn’t need an undercoat but just needs really exact and bold copy-tracing, you’ll do this much better because of what else you also know.

See what you’ve done by learning “our” approach is you’ve learned how to observe and concentrate better, and these qualities are really essential for glass painting.

But there’s more to it than even this.

And it’s not even that this once-firing technique can save you time and money. Of course it can and will. But these are small benefits by comparison.

Yes, the really big benefit is that, when you only fire at the end, you’re able to continue responding to and adjusting all the different values of light and dark which are on your glass – whereas if you fire your trace lines and then do the shading, well, you’re stuck with them, aren’t you?

Sometimes that’s a good thing. Say when geometry and intense symmetry are involved. Yes? This is where the “trace/fire” approach (as we call it) – i.e. where you trace the lines then fire them in the kiln – is excellent.

But what about more fluid things with texture like clouds, fields, petals, hands, eyes … the list is endless. What about them, and the gentle fluidity they often want?

Ancient knowledge and the Industrial Revolution

Most likely the “trace/fire” approach became dominant during the Industrial Revolution.

Imagine all the activity in those big 19th century studios … all those church windows which had to be produced incredibly quickly and almost as if they were on a conveyor belt in order for the studio to return a profit.

Here’s where the temptation arose to abandon ancient knowledge in order to “simplify” the means of production.

Another casualty was oil-based painting. You see, if you’re just using water-based trace lines with the right amount of gum Arabic, then you can afford a certain amount of rough handling of the pieces without risking any damage to them. You can even pile them up on top of one another on the way to the kiln. Believe me, I’ve worked in a big studio – not a nineteenth century one of course – and that’s exactly what happens. So we weren’t allowed to use oil …

Because the moment you add oil (which doesn’t dry, and doesn’t contain gum), then you’ve got to slow down and pay attention.

Which we think is usually a very good thing.

I mean, are we painting glass or are we trying to imitate a machine that prints paint on glass?

You decide that question and its consequences for yourself.

So anyone who’s interested in the idea of painting on glass (as opposed to behaving like a mechanical printer) can find loads of information right here on this web site. Just browse, read, experiment and enjoy.

And now to return to the excellent question …

Mistakes happen – but are they really unacceptable?

We’ve already mentioned an important part of the answer. You see if you’re not painting something that requires mechanical precision, the first thing is, it’s essential to be realistic about what is acceptable and what isn’t.

Say there’s some variation in the darkness or the thickness of a particular line.

  • Think hard: does this really matter?

Imagine the window in context: this piece will be surrounded by many others, and you have to consider whether it will be seen from close-up or from a distance – this too makes an important difference.

Here’s what I mean. When you next can, go into a church, find some painted stained glass, and choose some pieces to look at ruthlessly and analytically. I’ll bet you start to see flaws.

But the point is, it’s oten wrong to call them flaws. These variations are part of their humanity. Think of silhouetted letters where some parts of the script are lighter than others. Close-up, this is a flaw. At a distance, there’s a gentle undulation.

Now believe me here, David and I are the last people on earth to tolerate anything that’s careless or messy.

But we know very well that, when you’re staring hard at a piece on a light box, your eyes and your mind will tend to pick up on all kinds of small things which aren’t really important.

So of course be critical but don’t let yourself be distracted by over-criticism. There comes a point at which finding fault with oneself is actually the lazy thing to do. Sometimes better to pay attention and advance and see how well – from a “mistake” – it’s possible to finish.

Mistakes happen – so keep your copy-tracing light

And here’s another benefit of our approach: copy-trace lightly and when you come to reinforce, chances are the mistake won’t show. In fact chances are it’s no more a “mistake” than the light sketch marks we make in pencil when preparing to draw or practice a line on paper.

But you must keep your copy-tracing light and dry (not too much water in the brush).

Contrast this with the tradional “trace/fire” apprach. Here you’re meant to do your stroke in one go, without going over it again (“because that’s what causes blistering” – what rubbish!). So there you are, with the glass on top of your design, painting dark traced lines (and probably feeling quite anxious because you’vegot to get it right in one go).

Now ask yourself this: done this way, isn’t pretty much every stroke a mistake?

Here’s why: because, with your glass on top of the design, it’s nearly impossible to assess correctly your density and thickness of line.

With our approach by contrast, you first “sketch” the main lines. Then you put the design on one side. And then you build up the main lines as required.

And here you’re focussing on the line on top of the glass.

So you’re paying attention to what’s really important.

You’re much less likely to make mistakes. If you do, consider this next point here …

Mistakes happen – so consider what you’ll do next

Here you are, copy-tracing a line, and something has gone wrong. Another thing to consider is this:

  • Now you need to think through everything else you will do with this piece of glass.

So suppose you’re planning on going right through to step 10 above – that is, you’ll be softening, reinforcing, painting on the back, and painting with oil …

You have to ask yourself: will anyone know about what’s just gone wrong, or is it rather like a footprint on the sand that the incoming tide will wash away?

Only you can decide.

Decide wrongly, and everyone will be required to live with your error for 100 years or more.

Decide correctly, and your painted stained glass window will possess some individual life of its own.

Mistakes happen – and what can you learn from them?

Say it’s genuinely something unacceptable: a blob of paint drips onto a painted nose.

Maybe you do need to start again. It happens. It happens to all of us.

The thing is, that blob is actually information, and the question is, What is it telling you?

Figure that out, and you’ll paint better next time.

So what might it be telling you?

Probably, something went wrong on your palette:

  • Did you load too much paint onto your brush?
  • Is the paint too wet?
  • Is the paint badly mixed?

You see, it’s no use deciding to rub out your work and start again unless you also figure out what went wrong.

See, rubbing things out sometimes becomes a distraction from not thinking.

People often think just because they’ve started again, they somehow deserve things to go right next time.

But life’s not like that. And glass painting isn’t either. You must change something.

And no, there isn’t a magic formula, a silver bullet: you must observe with your own eyes and think for yourself. That is one of the many joys of glass painting: it demands such focus from you. And once you start to give it that focus, you’ll see improvements every time you paint.

So don’t be too rough on yourself when serious mistakes occur. Remember you’re a glass painter (not a mechanical printing-device). Thank goodness.

I hope this all helps.

All the best,Stephen ByrneP.S. Remember the only way you can be sure of getting all the tips we publish is for you to join our free email newsletter. If you don’t, you’re missing out. Now more than ever it’s a good idea to improve your glass painting technique and keep it at its best. It’s quick, easy and free to join. We never share your details with anyone else. Start here today.

15 thoughts on “Stained Glass Painting: “What if I Make a Mistake …?”

  1. Very interesting! Now, being a novice, I feel like I started watching a movie in the middle.

    Where would you suggest a true novice with several years of leaded glass experience start?

    Thanks for the opportunity to learn.

    • Hello Michael,
      I’m glad you signed up for the free e-mail newsletter.

      It’s early days – you found us just 4 days ago. And now, every 5 days or so, you’ll get tips, ideas, photos plus online video.

      Little by little, a pattern will emerge. A body of knowledge will take shape.

      I know you’ll already know so much from your several years of leaded glass experience. I don’t mean you’ll know about stained glass painting. I mean you’ll know about concentration and having the correct attitude e.g. to bending the lead around the glass, and to soldering. These things will stand you in good stead.

      Myself, I’d also consider what kind of use I’d want to make of glass painting. So think that one through. By all means write us an e-mail and talk it over. The thing is, a destination in mind nearly always sparks the energy to set out and enjoy the journey.

      All the best,

  2. At risk of sounding smarmy, you are SO right about this.

    Firstly the series of mistakes which shape your understanding and knowledge allow you to create effectively. It is all very well wanting to get it perfect from go, but this is an imperfect world and we are imperfect people. The cumulative effect of all the little things which didn’t go quite right allows you, after these experiences, to navigate the the best truest path to the desired effect apparently effortlessly. You know the sequence of cause and effect on a base level as so skirt these things before they beome a problem. Rather like beginner soldering when you keep hammering away at a tricky joint with the effect that you cause more and more damage as the whole thing (literally) heats up to reflect your frustration.

    With experience, you stop, move on, and come back to it afresh – and with cooler head (and lead), it is done in a jiffy.

    Secondly, the minute flaws and faults which appear so obvious and glaring up close become a part of a whole when scaled up to an entire piece, and YES they do add humanity to the design. I remember a programme I watched years ago (and I don’t think I remember this in error) about rug weavers in India. One thing that caught my attention was that although the weavers were amazingly skilled they incorporated a small deliberate mistake into each rug because only God/Allah is perfect so to claim perfection is a form of blasphamy. Worth thinking about, religious connotations aside.

    • Such useful thoughts here e.g. about knowing when to leave a problem and return to it later; and also about the carpet weavers and their understanding that some measure of imperfection is actually part of human perfection. Thank you!

  3. Stephen,

    The question was very good but your answer is so explicit! Even I could follow it! The fantastic and priceless information from you is such a blessing to receive! Please keep up the lessons even though they are taking your time – so many others are learning an art form that we don’t want to die from lack of passing it on to others. You’re the best!


  4. Hi Guys!

    Even though I don’t do glass painting, I REALLY love reading your stuff, and I wish I COULD! But I just do normal stained glass work (leaded – very new – and copper foiling), and I love it.

    I hope to see you again soon!

  5. Greetings from Janae!

    I love getting all your updates with very useful information.

    One problem I’ve had is painting on both sides of the glass and trying to fire it as I normally do.

    What happens is that the top side fires fine but the bottom doesn’t fire and will wipe off.

    Any suggestions?

    Should I be firing at a higher temperature or longer when I do this?


    • Hello Janae,

      Thanks for your question.

      So, when you paint back and front and want to fire them in a single firing, the top side fires fine but the bottom side wipes off.

      One or more of three things are going wrong here.

      First, as you say, you need to increase the temperature, and maybe also the “soak” time at the top – this increased soak time will allow the heat to permeate down to the underside of the glass and so fuse the paint which lies beneath. This is the most likely solution.

      Second, it’s possible – just possible – there may be a complication caused by the surface on which you’re firing. We ourselves mainly use whiting (calcium carbonate). It’s also possible to use plaster of Paris, and kiln paper, and kiln wash and so forth. Clearly, different firing surfaces can interfere in different ways with the way in which your glass paints fuses to the glass.

      Third, less likely still, it’s the glass. (I say “less likely still” because we’re talking here about glass paint, not silver stain.)

      I’d say, try the first hypothesis first: that is, increase the temperature and/or the soak time, and then let us know how things are.

      All the best,

  6. Thanks for the comments about correcting errors. They reminded me of an old tip from a model railways enthusiast: he called it the “2-foot rule”.

    Essentially, it’s pointless putting in every rivet on a 1:76 scale model because it’s going to be seen moving past at speed, and the viewer is almost never going to see the model closer than a yard away. Sure it’s a mighty achievement to build a model train with individually upholstered seats and a flushing lavatory, but if it can’t be seen, why go to the bother?

    And thus with a stained glass piece that’s possibly going to be many metres up in the air, or a piece with a small flaw that will end up in the middle of a large panel surrounded by many others pieces of an overall design.

    Try propping the piece in question up a few feet away and ask yourself honestly if you can still see the glitch. Ask someone else to have a look at it and see if they can see anything wrong. I’d suggest that mostly, the only person who will pick the mistake will be the artist who made it, and nobody else.

    And if it is something like a blot on an eyeball or something hideously noticeable, do what you do when you lose a piece you’re cutting: mutter to yourself “oh dear, you naughty piece of glass”, think about what went wrong and how not to do it again, and then cheerfully get on and redo the thing.

  7. I really like the “2-foot rule”.

    All the same, a mistake is just that and nothing else.

    Generally, therefore, I myself would not take any comfort from something’s being a mistake that “couldn’t be noticed”.

    It’s still a mistake.

    But, when you’re painting one of the bird roundels, for instance, and, during copy-tracing, part of the beak is thicker than you’d intended, you have to ask yourself: does this really matter?

    The answer is, Probably not – precisely because you’re going to strengthen it, block it in, and then shade with oil.

    Another example – one which is directly relevant to R-tist-Dug’s example of the model railway.

    Speaking to you as someone who spent the best part of 4 years restoring and conserving 19th century glass from all over the world, I had the daily opportunity to examine closely hand-painted bits of glass which were meant to be seen from afar.

    And let me say this: they did not work.

    Not close up they didn’t.

    Thing is, if they had worked from close, they would have failed when seen from afar.

    So I have seen my fair share of crude thick lips and bulbous insensitive eyes.

    What I mean is that I’ve seen enough to know how these lips and eyes became obects of breath-taking delicacy when placed 20 feet up in the east window of some historic English church.

    And if they had struck me as delicate from close-up, I am sure they’d have been unnoticeable from afar.

    Which would have been a mistake – and ruined the window.

  8. Hi, David and Stephen!

    Making mistakes, as you rightly suggest, is the perhaps the best way of learning and how taking a back step to see what went wrong should ensure that basic errors don’t occur again.

    Perfection is in the eye of the beholder and we are perhaps our own worst enemy in looking at our work with the keenest of criticism. In my former life, I was in PR and looking back, I spent most of my time writing copy, then editing, rewriting etc. Funnily enough, I almost always ended up with the original copy and a few educated tweaks, as the copy came from the heart. And perhaps that is where the best, fresh looking and original stained glass painting comes from!

    Keep up the great work and thanks for your continued inspiration to us all.

  9. Hi Eileen,

    I think you’re “spot on” with your comment about coming from the heart.

    It’s definitely possible to tell the difference between a brush-stroke with life and a sterile one …

    Which is why using a stick to re-shape a dried traced line easily destroys the grace it once had.

    Indeed it’s often better to have a slightly uneven and graceful line than a line that’s been carved and corrected out of existence.

    All the best,

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