Film and Halos around painted lines

[TiffGeorge]

So I’m struggling with what I can only think to call “halos” around my painted lines. This is to say that I’m experiencing a strange film on my glass after it has been fired, but this film is conspicuously absent in the form of a halo around each line. If this were happening on purpose it might be neat, but unfortunately it’s just very very frustrating. A second layer of paint will hide it, but in some cases the effect is so striking that a secind layer only makes it more noticeable. (Such as in the blue hydrangea flowers below.)

It happens on almost all types of glass - from all manufacturers. (With the exception of some float glass.) It happens regardless of my painting medium. (Glycol or water with gun arabic.) I’ve tried different temps, different glass (so much glass), different paint, different brushes, different cleaners/glass prep, different cleaner/prep applicators, different glycol, different water, different hold times… and the only change is that now it seems to happen to every single piece. If anything it seems I’ve somehow made it worse.

It has happened in numerous different kilns at my local studio. It has however never happened to me in any gas fired kiln. I don’t believe it is the fault of the electric kilns - otherwise wouldn’t this be happening to more glass painters? I’m running out of variables that I can think of.

My last idea is to try a fiber shelf, as someone mentioned it may be a reaction between the kiln paper and the paint. But I’ll need to find some advice on that as I don’t know what’s appropriate and I don’t currently have the budget to buy many different shelf options. I am trying to save up to rewire my house so I can run my own kiln, but for now I’m stuck paying for each test firing - and that’s not helping me save.

Has anyone seen this phenomenon before? I’ve reached out the the SGAA, Deb Coombes, and a few other friends - but we’re all puzzled.

[Barry Kaiser]

Instead of glycol and water based mediums, use A-14 or pine oil.
Your problem is probably the medium

[Brad Walker]

Instead of glycol and water based mediums, use A-14 or pine oil.
Your problem is probably the medium

Agree.

[TiffGeorge]

Instead of glycol and water based mediums, use A-14 or pine oil.
Your problem is probably the medium

But why would that be? If it’s a medium issue, then wouldn’t I see the same results in either kiln?

[Brad Walker]

Instead of glycol and water based mediums, use A-14 or pine oil.
Your problem is probably the medium

But why would that be? If it’s a medium issue, then wouldn’t I see the same results in either kiln?

If I've read your post correctly, the problem occurs in electric kilns, but not gas kilns.

The binder suggestion is easy to test, just try with a different medium.

I don't think it's the shelf, and even if it was, a fiber shelf is more likely to cause trouble than a clay shelf.

[TiffGeorge]

Instead of glycol and water based mediums, use A-14 or pine oil.
Your problem is probably the medium

But why would that be? If it’s a medium issue, then wouldn’t I see the same results in either kiln?

If I've read your post correctly, the problem occurs in electric kilns, but not gas kilns.

The binder suggestion is easy to test, just try with a different medium.

I don't think it's the shelf, and even if it was, a fiber shelf is more likely to cause trouble than a clay shelf.

If I've read your post correctly, the problem occurs in electric kilns, but not gas kilns.

—-Correct. I don’t have the wiring capacity at my home for a kiln, so I’ve used other kilns when I can. Some gas - no problems. (Other than my own accidental over-firing once.) But all three electric kilns I’ve tried at the local glass shop have had the issue. I believed at first it was the operator changing my firing schedule. (She is very hesitant to fire the way I have asked. Her background is in fusing, and she wants to go painfully slow, and has at least a few times decreased my ramp speed to 250 an hour and tried to add hour long hold times at multiple steps. I only discovered this when she fried my silver stain.)

—-Eventually we came to an understanding on the firing schedule, but that didn’t really improve the halo issues. I’ve tried 4 different mediums. I guess now I’ll try a 5th.

—-But this issue didn’t occur in any of the classes I took, using the same paint or medium - even from the same batches. And in at least two of those classes the kilns were also electric. So it just doesn’t make sense to me that I would have this problem only when firing at the local glass shop with her kilns.



The binder suggestion is easy to test, just try with a different medium.

I don't think it's the shelf, and even if it was, a fiber shelf is more likely to cause trouble than a clay shelf.


—-I wondered if it was perhaps the paper she uses on the shelf. That isn’t something I’ve seen any of the other painters I’ve learned from use. They all seemed to prefer fiber shelves or whiting trays. I believe one even used uncoated 1/4 float glass as the shelf. I’m not brave enough to try that necessarily, but maybe once I’ve got my own kiln to experiment with.

[Brad Walker]

—-I wondered if it was perhaps the paper she uses on the shelf.

Another possibility that makes sense. The paper, perhaps combined with the type of kiln.

[Buttercup]

I won't wade into the 'halo' discussion as I've not experienced it.I'd like to make a suggestion about your house wiring in preparation for a kiln.

Disclaimer: I am not an electrician. This is about my personal experience.

Unless your house is really old with dodgy wiring that should be replaced anyway, you might already have a less expensive option than a complete rewire. Do you have an electric oven or an electric dryer? If so, look for the specs. on the appliances. I'd be surprised if they are not 220-240V and either one could share a circuit with a kiln. You'd just have to remember you can't use them simultaneously.

I haven't lived in North America for a long time but for many years my kiln and dryer shared a circuit with no problems. Speak to a qualified electrician. You could save a lot of money.

Good luck with both your issues. (I've never had the halo effect. I fire painted glass on alumina Hydrate in an electric kiln).

EDIT: 1. Just noticed that the problem only happens wit the one set of kilns. Is it possiblle that those kilns are all contaminated? You said that your silver stain was over-fired there. Maybe something else was.
2. Does anyone else who uses those kilns have the problem?

Over to someone who might know..........

[TiffGeorge]

So far only I have had this issue… but I’m also the only one trying to paint at the studio. All the other users slump and fuse. I’m a bit of a novelty here.

[TiffGeorge]

I

EDIT: 1. Just noticed that the problem only happens wit the one set of kilns. Is it possiblle that those kilns are all contaminated? You said that your silver stain was over-fired there. Maybe something else was.
2. Does anyone else who uses those kilns have the problem?

Over to someone who might know..........

So far only I have had this issue… but I’m also the only one trying to paint at the studio. All the other users slump and fuse. I’m a bit of a novelty here.

[Buttercup]

Just came across this older thread where one of the contributors mentions a film on the glass. I don't know if it's the same problem as yours but the answers that follow may help you:

viewtopic.php?p=363859&sid=5b17e9dc7625 ... e0#p363859

[TiffGeorge]

So after a dozen more tests, it appears it may have been a reaction between the black and the bullseye thin fire paper. Once I convinced the kiln operator to fire without the paper the problem seems to have resolved. We ran a few more loads just to make sure it wasn’t a fluke… and so far so good. Now if I only understood enough about the chemistry to know why this happens.

[David P]

Did the original poster find out why the Thin fire paper was creating a halo effect with the black paints?

[Don Burt]

I'm not happy with the conclusions. I use shelf paper a lot and trace with black paint. I do get fogging in certain situations: on float tin side when it is fired above 1300F, and when I'm using copper stain. I want to see what happens if you go to Ms. Rent-a-Kiln's place, distract her or lock her in a utility room, do a firing with a square of glass on her shelf paper with no paint. and one with tracing paint placed far away in the kiln, on no shelf paper. Program the kiln yourself and don't let her out of the closet until she swears not to change the program. I think her kilns might have some atmosphere contaminations, and the paint is protecting the immediate area, or there's an unconventional thermal adventure that the glass is being subjected to.

[Buttercup]

Maybe the contamination has burned off now?

There's a proper scientific term for that, I'm sure, but it's late.