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crystals in the glaze buckets

updated thu 3 feb 05


Linda Ferzoco on mon 31 jan 05

Here are some images of lithium crystals

Lori Richter on mon 31 jan 05

This has been discussed a couple times before - however, we'd like to =
offer someone the opportunity to take some of the crystals found in our =
glaze buckets and see if they can figure out what's "making them tick" - =
a chemical analysis?

Mug shots of the offenders can be viewed here:

Please bear in mind that I'm slightly camera challenged - still haven't =
figured out how to use the Macro-Mode on this thing.

The story:

A couple years ago we noticed crystals in 2 of our glaze buckets (2 =
majolica glazes that contained Lithium Carb.) that had been stored in a =
colder part of the room. =20

Most of the crystals were melted in warm water and added back into the =
buckets. The remaining crystals were given to the Chemistry department =
to dissolve and analyze. Unfortunately, we still have no clue what's =
happening - they can't seem to get past the sodium. =20

We've now discovered crystals in 3 more of our glazes as seen in the =
gallery. All 3 of these glazes use the same base - different colorants.

After coming back from the holiday break, we were changing out the glaze =
buckets and found these beauties! The crystals from the Glossy White =
are so fragile, they will probably make it to their destination in =
powder form. The Black ones are like tiles - but, come apart so easily =
that I couldn't rinse them for their portraits. However, the Yellow =
Clear lovelies are just that - HUGE!!! and thick and incredible to look =
at close up.

The glazes have been sitting, unstirred, for approximately 2 months with =
the heat down, so that it's fairly cool in the room.

All the crystals pictured were found sitting on top of the settled =
glazes, under the water line. There were numerous smaller crystals =
throughout the settled glaze. The boss feels that they grew larger on =
top due to the exposure to the water. Oddly enough, no crystals were =
found in the Clear glaze used as the base for these 3. Or, if there =
were any, I didn't notice them. The only time we find the crystals is =
when it's cold.

If some adventurous soul would like to take a closer look, I'll mail =
them a sample of each of the 3 crystals pictured if you'll provide me =
with a mailing address.

Thanks much,

Freeport, IL

Still the Chief Gofer, full-time PITA and General Nuisance

John Britt on mon 31 jan 05


Nice Crystals! Looks like you have a crystal factory there.

I have an article on the subject in the Jan/Feb 2005 issue of Ceramics
Review which will tell you all you want to know. As you know this has been
discussed on Clayart many times and Tom Buck and Michael Banks have said
that they were Lithium Tetraborate crystals. I had my analyzed by X-ray
Diffraction (XRD) and found that some did contain a type of borax (Na2B4O5
(OH)4=958H2O), while others contained lithium borate hydrate (Li2B2O4=9516H2=
along with miscellaneous minerals like quartz, feldspars and trace

Hope it helps,

John Britt

John Britt on mon 31 jan 05

Another interesting thing about these crystals is that they dry out if
taken out of the glaze bucket and become brittle over time. When touched
they will just fall to dust. Seems that they need water to keep the
crystal intact. (I think I remember that opals also need to be kept wet?)

John Britt

Wes Rolley on tue 1 feb 05

Louis Katz wrote:

All of this talk of crystals in the glaze bucket reminds me of something
I read a long time ago, about the worlds largest crystal of spodumene.
I looked it up again and found a reference here ( ) but no

The single crystal was 12.7 x 1.7 meters and weighed 90 tons.

A bit too big for a glaze bucket.

Louis Katz on tue 1 feb 05

Hi Lori
My guess is the glaze has Lithium and Boron in it. Usually Gertsley B.,
or Cadycal. I would guess the lithium is the carbonate.
If these guesses are correct try recalculating the glaze with a frit,
and if possible Spodumene. If the boron is too high for this option,
try a different recipe.
Option 2 is to remix the glaze every few months and fill up the

If this is Lithium Borate (just a guess on my part) here is a link:

On Jan 31, 2005, at 6:40 PM, Lori Richter wrote:


Shawn McGuire on tue 1 feb 05

Funny, I too have had crystals appear in my glaze this past week. Little
hexigonal flakes. I have used this same glaze before and never had this happen,
I suspect that the temp. in my studio has something to do with it, it's damn
cold here in upstate NY. I actually proceeded to glaze about a half a kiln
load worth of pots with this glaze, partly because I wanted to see if something
interesting might happen and mostly because I was in a hurry. The kiln is
cooling now so I can report back tomorrow with results, although I suspect I
may be disappointed.