Glass Paint – How Long Can You Keep It For?

A good question from a colleague in Maryland, USA:

I am an experimental physicist in mid-career and very busy with work – so my time spent on stained glass and glass painting is very sporadic – it has been 8 or 10 months since my last project.

Is it OK to make the lump of paint (as you teach) and leave it for 6 months to a year?

Should it be tended to periodically over that time?

Will it “come back” and be usable after a very long time?

And the answers are …

1: Yes. 2: Not necessarily. And 3: Yes, indeed.

Now David is pestering me to get on with my painting, so I must fly.Stephen ByrneP.S. Oh I’m too thorough for my own good – those columns will have to wait a bit longer …

As always, we can only ever tell you straight what works for us. Now maybe it’ll all work the same for you. Or maybe you’ll need some fine-tuning. But if at least you know it’s possible – whatever “it” is – that will give you confidence you’re not stumbling in the dark. And you’ll then be able to figure out your own way.

Which is how we like to teach – because it’s best for you.

Here in the studio we often mix large quantities of paint. Say a good six ounces (170 g). Maybe more. Because it’s useful to have it ready for when we need it. See here our studio “tub” of tracing black and tracing red:

The studio tub of ready-to-go glass paint

The studio tub of ready-to-go glass paint

This tub contains paint we prepared at least six months ago (though I added more black in February). And we’ve “raided” it many, many times, so it’s much, much smaller than it was. (There’s maybe “just” enough paint for two more full-sized lumps – still a good amount – and then we’ll make another batch.)

You can see how the paint itself has fallen to the bottom but still remains sticky. And you can also see how the fallen paint has displaced the water to the surface which it keeps wet.

Now this is also important: just as David or I will help ourselves to a spoonful or two from time to time, and mix it in with the paint on our palette (which doesn’t take long at all), so we might also scrape our palette clean and mix it all in with the paint in the studio tub. Because that’s the best place for it if we don’t plan to use our lump again this week.

Does it need looking after? Not especially – that’s our experience. Obviously keep it cool. In summer we might sprinkle a few extra drops of water on the top. And of course it’s always sealed. In our case with a thick piece of heavy glass (which we wet with water so it dries and sticks):

Just be sure to seal the tub

And yes I know we’d be better off with an airtight lunchbox but I guess that’s maybe a bit too modern for us!

One last point: we’re a busy, working studio, and the question came from a colleague who doesn’t get much time to paint, which is a very different situation, maybe more like yours.

And here’s what I’d suggest. Get yourself a medium-sized (airtight!) lunchbox. And prepare a larger lump than usual – say, twice the normal size. Keep half in the lunchbox. And spend whatever time you have, painting with the other half. When you’ve finished – and know you won’t be painting for some time – add it to the lunchbox where the quantity of paint will keep it all in a good condition.

I hope this all helps.

Now back to those columns …Stephen Byrne

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5 thoughts on “Glass Paint – How Long Can You Keep It For?

  1. Hello Stephen,

    Thank you again sharing your knowledge with us. I learned a good lesson from you and David about painting with a lump (not a teaspoonful) of paint. But to start with, I didn’t think how dusty my workplace was (dust from glass and also from old lead because I also do restoration). This was a good (hard) lesson for me because I had to start all over again. Now I always keep my lump covered under an old cup.


  2. Hello Stephen, hello David,

    It is always good luck to open my mail box and find one of your posts.

    As for this one, it happened that I just starting to paint one of your e-books designs, but I had redrawn it to larger scale … I therefore needed to mix a large amount of tracing paint, so I went and mixed a full 2 ounces of black and bister brown like you suggested in your e-book. And it was a good thing I did so, because usually after doing some tracing, I find myself needing to mix more paint which sometimes doesn’t behave the same like the previous batch. And so I need to add more paint or more water etc. etc. to try and make it the same.

    But this time mixing a larger amount did help me to have the same grade of paint right through all my tracing. And also what’s leftover can be saved for later projects!

    So thanks again for your help. It really came in good time 🙂

    Hassan (in Kuwait City)

  3. Hi Stephen,
    Have you and David been really busy? I haven’t received any emails lately. I miss them!

    • Hi Sue,

      Yes, very busy – I’ll write start again soon with lots of new and useful things. I hope all’s well with you.


      P.S. I’m glad you miss hearing from me …

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