Lou Roess on mon 31 jan 05
I have some lepidolite at the school studio that no one is using
because we have no recipes that use it. I understand it's no longer
produced, but does anyone have any recipes that would use it up? What
qualities does it give to a glaze? Are there current ingredients that
do as well or better and should I just forget about it?
TIA
Regards.
Lou in Colorado
Daniel Semler on wed 2 feb 05
Hi Lou,
I have not used lepidolite but I did a quick search (googled I guess would be
the "new" verb). There are some recipes out there. Lepidolite is a lithium
containing feldspathoid. It seems to be able to supply about half the lithia of
spodumene, a lower silica content and more alkali. It would probably help keep
expansion under control pretty well. With some recalculation you could sub it
into a spod glaze and see what gives.
Hamer and Hamer note that it can be subbed for other spars, giving earlier
fusion and increased shine. It contains flourine which can cause some pitting
in the surface if you have too much of it. Interestingly it does not contain
lithia, but rather contains LiF and must draw in oxygen to form lithia. Ditto
with the K. (see http://ceramic-materials.com/cermat/area.php?area=1&id=963&)
What an interesting material !
Certainly worth experimenting with if you have a bunch, I'd say.
Thanx
D
Carolynn Palmer on wed 2 feb 05
I do not know anything about lepidolite, but ran across this glaze in an old
book.
In my 1980 edition of "The Potters Book of Glaze Recipes" by Emmanuel Cooper:
Glaze for cone 7, 8 & 9
50 Lepidolite
20 Barium Carbonate
5 Whiting
10 Ball Clay
15 Flint
A matt, decorative glaze, best fired in oxidation.
Smoothest on porcelain with a tendency to bubble on stoneware.
Variations:
Add 1% nickel oxide for a pale grey pink
Add 1% copper oxide for a rich pale turquoise
Add 1% manganese oxide for a pale pink
Ben Shelton on thu 3 feb 05
"Here are a couple of links"
http://www.mindat.org/min-2380.html
http://mineral.galleries.com/minerals/silicate/lepidoli/lepidoli.htm
Source of lithium.
If you have any glazes that use lithium, you could easily compute to
substitute lepidolite.
Hope it helps, Ben
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