funky etching happened in the kiln

Beatrix92 · #1 2013-01-14, 1:07pm

I made a batch of beads, they were either grass green opaque or nile green opaque (the rods got mixed up) and when I took them out of the kiln they were etched. I had other beads in there that were fine. Just the green ones turned funky. Any ideas on what the heck I did?
Thanks!

Anne Londez · #2 2013-01-15, 4:03am

That sounds like reduction. What kind of kiln do you have ? It can happen with gas kilns but rarely with electrical kilns. Or it could be devitrification. Do you have pics ?

Beatrix92 · #3 2013-01-15, 12:48pm

I have a paragon caldera, and It isn't discolored at all just a matte surface. I will post pictures tomorrow.
THANK YOU!

Three Muses Glass · #4 2013-01-15, 1:50pm

Kind of sounds like reduction to me too. Like the silvery/grayness you can get on copper green, many of the effetre greens can be prone to it, same as if you hit them with a redux flame on purpose they can go red or livery.
A short soak in toilet bowl cleaner should be able to tell you if it's just surface schmutz. Sometimes the soak and a quick scrub with an old soft toothbrush will get it off if it is just surface.

lindag · #5 2013-01-15, 2:29pm

Do you use your kiln for other things than glass? I remember that many years ago there were some issues with annealing beads in kilns also used for PMC. Did you have any EDP or Sedona or such in the kiln a the same time? Something might share some devit?

Beatrix92 · #6 2013-01-16, 8:59am

I will try the toilet bowl cleaner tonight! Thanks!
Lindag, there was one bead with unencased Triton, but the only thing I use my kiln for is annealing the beads. I soaked them in vinegar and cleaned the bead holes befor the annealing process, could that have done anything?
I forgot to post the pictures, I will do that tonight!
Bea

DreamMuse · #7 2013-01-16, 11:11am

Were you batch annealing? I had a problem like that with pastel Cobalt a few years ago, when I used to batch anneal. There wasn't a solution, unfortunately.

Beatrix92 · #8 2013-01-18, 7:58am

I was batch annealing. I will try garageing them instead. The toilet bowl cleaner didn't work =( and I can't seem to get the pictures to load.
Bea

Alaska · #9 2013-01-18, 2:40pm

One could also try a few beads that were NOT soaked in vinegar as this is a mild acid. Perhaps there is a little residue remaining on the bead and that combined with heat accelerated the etching action. Just a guess on my part.....

Ravenesque · #10 2013-01-20, 3:08am

Yes could be the vinegar http://www.lampworketc.com/forums/sh...t=vinegar+etch

Anne Londez · #11 2013-01-22, 6:03am

Vinegar cannot etch glass but it could leave a residue that may solidify in the kiln I guess.

Eileen · #12 2013-01-22, 8:36am

Anne, it etched my goddess bead, but it was while I was soaking it in a vinegar/water mixture before cleaning. I ended up etching the whole thing because that was the only way to "save" it. None of the other beads soaking with that one had any ill effect.

Ravenesque · #13 2013-01-23, 12:24am

Yeah mine was post kiln, I was soaking like Eileen. I did this for years like that and it never happened before, I do not use vinegar anymore since my fusion comes off so easily.

Anne Londez · #14 2013-01-24, 1:46pm

There may be some sort of reaction between vinegar and the metals that come up to the surface of some colors but that is not the same as etching. Etching is the breaking of a silicon-silicon bond and only very strong acids can effect that from a chemical point of view.

Lyssa · #15 2013-01-24, 2:21pm

This has happened to me.

See here for a discussion of the problem.

And there's this one too, in case that relates.

allicat · #16 2013-01-25, 4:44am

Just want to share an observation; it may or may not help LOL

While taking last nite's beads out of the kiln, I noticed a bead sitting on the floor of it. Was one I did during a batch anneal and it must have fallen off. I have a Paragon, so it's fiber lined. The bottom of the bead, which was sitting on the fiber, is clearly etched; the top, which was in the air, is partially etched - just a little bit of shine left. It seems to me touching the fiber has had some kind of effect on the glass, and I wonder if that's what happened with yours?

Alli

bshelle · #17 2013-01-25, 7:13am

What temp are you annealing at?

Lyssa · #18 2013-01-25, 9:10am

In my case, I tried many variables. Laying them on the fire-brick floor of the kiln, laying them on fiber blanket, putting them on mandrels (touching other beads and not touching other beads). They always came out etched to some degree around the hole.

This was ONLY when I used to batch anneal, though. Now that I have my handy dandy Glass Hive kiln, I don't batch anneal, and this has NEVER happened to me when I batch anneal.

Quote:

Originally Posted by allicat

Just want to share an observation; it may or may not help LOL

While taking last nite's beads out of the kiln, I noticed a bead sitting on the floor of it. Was one I did during a batch anneal and it must have fallen off. I have a Paragon, so it's fiber lined. The bottom of the bead, which was sitting on the fiber, is clearly etched; the top, which was in the air, is partially etched - just a little bit of shine left. It seems to me touching the fiber has had some kind of effect on the glass, and I wonder if that's what happened with yours?

Alli

Beatrix92 · #19 2013-01-25, 1:19pm

I anneal at 950 and I have a caldera kiln and the beads were on a kiln washed ceramic shelf. I believe that at least partially has something to do with the vinegar. I did a test. made 20 spacer beads from the same rod. Some I cleaned in vinegar, some I didn't. Ran them through the annealing cycle, and all the vinegar beads were that partially etched surface, and the others were not. They weren't as shiny as they were before, though, so maybe it is partially devit and partially vinegar?

*Naos* · #20 2013-01-25, 1:25pm

Remember, when using silver glass, anneal at 920, sometimes lower...

castaway · #21 2013-01-25, 3:37pm

good heavens do people anneal effetre above 900 F ????

eregel · #22 2013-01-25, 3:40pm

I anneal at 940.

castaway · #23 2013-01-25, 3:43pm

interesting, the Italians anneal at 480 C why would you do it so high?

eregel · #24 2013-01-25, 4:45pm

Because everything I've ever read anywhere suggests 920 - 980.

Lyssa · #25 2013-01-29, 7:13pm

You're supposed to garage at 920F to 980F, for the sole purpose of having some wiggle room in your temp when you open your kiln to put new beads in.

The actual temp where you're "annealing" (releasing the stress in a bead) is 840F. That's the temp where the microscopic crystals of 104 glass are still moving enough to align themselves to each other and release their stress but is solid on a macroscopic level.

That is what every reputable source I've read has said, not just the never-ending game of telephone we get here on LE.

Hope that last doesn't piss anyone off.

Judith Billig · #26 2013-01-29, 7:36pm

Me thinks there is some confusion happening between Celsius and Fahrenheit.
Italy uses Celsius.
480 Celsius = 896 Farenheit.

Lyssa · #27 2013-01-29, 9:54pm

Quote:

Originally Posted by Judith Billig

Me thinks there is some confusion happening between Celsius and Fahrenheit.
Italy uses Celsius.
480 Celsius = 896 Farenheit.

LOL

Frit Diva · #28 2013-01-29, 10:33pm

I think we may also be having some vocabulary confusion on the subject of annealing.

840F is the lower strain point for most 104 coe glass, not the annealing point. This means that any internal stress in the glass cannot be relieved until the glass reaches at least this temperature. The upper strain point is the temperature at which the glass will begin to deform. Temperatures between the lower and upper strain points are all potential annealing temps, depending on a multitude of factors. Due to the differing mineral composition of the different colors and the base glass made by different manufacturers, the process of relieving molecular strain occurs at different temps for different glass colors, and has a variety of trade-offs.

Higher temperatures that are still below the upper strain point (the temperature at which the glass would be begin to change shape) will relieve the internal strain much more quickly than lower temps, but may also cause color changes and run the risk of the glass shifting or sticking. On the other hand, if you tried to anneal at 840 F, you would need to let your kiln soak at that temp for at least 5 or 6 hours to relieve the stress that can be relieved in a few minutes at 940 F. Other factors also help determine the optimal annealing cycle for any particular glass.

Once the glass has had time to soak at whatever temp you decide is best to anneal your glass, it can be cooled to the lower strain point and then allowed to rest there for some period of time before the controlled cooling to room temperature is begun. I personally like to let the kiln rest at 840 for an hour to be sure all the molecules are done rearranging themselves, but other people may choose differently. As the temperature falls below 840 F, you are no longer annealing, you are now doing a controlled cooling to avoid adding in more strain.

Hope some of that info is helpful to somebody ~ this is why discussions of annealing are so complex!

Jo

Lyssa · #29 2013-01-30, 10:33am

Jo, this is definitely helpful! I actually remember reading that in my sources, but (due to lack of memory in my ol' noggin) I distilled and stored the information down to the simple "840 is the annealing point as long as you soak it long enough". I remember now that my sources pointed out that you can anneal in a range of temps, from 840 up to when the glass starts to move. Thank you for the reminder!

The trick is to ramp down below 840 slowly enough not to reintroduce strain.

Quote:

Originally Posted by Frit Diva

I think we may also be having some vocabulary confusion on the subject of annealing.

840F is the lower strain point for most 104 coe glass, not the annealing point. This means that any internal stress in the glass cannot be relieved until the glass reaches at least this temperature. The upper strain point is the temperature at which the glass will begin to deform. Temperatures between the lower and upper strain points are all potential annealing temps, depending on a multitude of factors. Due to the differing mineral composition of the different colors and the base glass made by different manufacturers, the process of relieving molecular strain occurs at different temps for different glass colors, and has a variety of trade-offs.

Higher temperatures that are still below the upper strain point (the temperature at which the glass would be begin to change shape) will relieve the internal strain much more quickly than lower temps, but may also cause color changes and run the risk of the glass shifting or sticking. On the other hand, if you tried to anneal at 840 F, you would need to let your kiln soak at that temp for at least 5 or 6 hours to relieve the stress that can be relieved in a few minutes at 940 F. Other factors also help determine the optimal annealing cycle for any particular glass.

Once the glass has had time to soak at whatever temp you decide is best to anneal your glass, it can be cooled to the lower strain point and then allowed to rest there for some period of time before the controlled cooling to room temperature is begun. I personally like to let the kiln rest at 840 for an hour to be sure all the molecules are done rearranging themselves, but other people may choose differently. As the temperature falls below 840 F, you are no longer annealing, you are now doing a controlled cooling to avoid adding in more strain.

Hope some of that info is helpful to somebody ~ this is why discussions of annealing are so complex!

Jo