Carol Tripp on wed 11 may 05
'Morning,
I'm coming out of deep lurk mode here. I mix up all the glazes we use at
the Dubai Art Centre (unpaid labour in 100F/36C outside area) and I finished
up all the flint yesterday (don't ask, I've been pointing out this impending
lack of supply since Oct 04). The problem is, we are nearly out of a white
glossy glaze. Our students love to use glossy white and I know there will
be complaints heard if we don't have any. After all, one must have glossy
white to go with the shiny blue ;-)
We fire in an electric kiln at ^9-10. I went home and fiddled around with
GlazeMaster for a few hours and came up with the following glaze which I
think might be glossy white:
10 Neph Syn
29 Wollastonite
15 Petalite
33 Potash Felpspar
11 Zircopax
2 Bentonite
Tin Oxide 3%
I have no experience formulating glazes from this particular direction and
the above is just one of many guesses I arrived at. The Art Centre has
quite a good range of glaze chemicals but no strontium or spodumene.
Does anyone have any thoughts or pointers? I know that one must test test
test, but the term is running out soon and I need to get a move on. I am
willing to 'fly by the seat of my pants.' And, what is the worst that can
happen?
Thanks in advance for any help.
Best regards,
Carol
Dubai
_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today it's FREE!
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/
Lee Love on wed 11 may 05
Don't know if this helps, but..... My traditional glaze recipes from the
Tochigi Ceramics Institute do not use flint. They use Oyatsu sand. Got
any sand in Dubai? :-)
--
李 Lee Love 大
愛 鱗
in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft
John Hesselberth on wed 11 may 05
Hi Carol,
It is good to hear from you again. You have been pretty scarce recently.
Your glaze looks pretty good from the unity numbers standpoint, but you=20=
may have trouble with 1) crazing 2) hardpanning in the bucket, and 3)=20
it may be semimatte with that much opacifier (both tin and zirconium).
You probably don't need both the Zircopax and the tin oxide to get a=20
opaque white. I usually use 5-6% tin or 10-12% Zircopax, or lessor=20
quantities of both. I noticed you put the Zircopax "above the line". I=20=
assume this was so its silica would be included in the unity=20
calculations. Zircopax doesn't have much solubility in a glaze so even=20=
though you did it in the calculations that is probably not what will=20
happen. But even with Zircopax "below the line" as an additive you=20
still have enough silica to make a durable glaze for this purpose.
I would try to get a little clay into this glaze. Otherwise you may=20
have serious hardpanning in the bucket. While 2% bentonite will help,=20
I'd be a lot more comfortable if you had some ball clay also.
As to expansion, I would get rid of the neph sy and put in some talc.=20
That will help quite a bit.
I fiddled a bit more and came up with the recipe pasted below my=20
signature line. I wouldn't use this as a general purpose base glaze=20
(especially not with copper), but it should be fine durability-wise for=20=
your white glossy glaze. I would also point out there are several other=20=
ways one could approach this so you will probably get some responses=20
that look very different.
But now tell me again. You ran out of silica in the middle of the=20
desert???????
Regards,
John
--------------
Recipe Name: Carol's White
Cone: 9-10 Surface: Glossy Color:
Firing: Oxidation Surface: Glossy
Amount Ingredient
35 Feldspar--G-200
29 Wollastonite
15 Petalite
12 Ball Clay--Old Mine #4
9 Talc
100 Total
Additives
2 Bentonite
3 Tin Oxide
6 Zircopax
Unity Oxide
.054 Li2O
.05 Na2O
.104 K2O
.198 MgO
.594 CaO
1.000 Total
.319 Al2O3
.004 Fe2O3
2.573 SiO2
.005 TiO2
8.1 Ratio
70.8 Exp
Comments:
-----------------------------------
Calculations by GlazeMaster=99
www.masteringglazes.com
------------------------------------
On Tuesday, May 10, 2005, at 11:57 PM, Carol Tripp wrote:
> Does anyone have any thoughts or pointers? I know that one must test=20=
> test
> test, but the term is running out soon and I need to get a move on. I=20=
> am
> willing to 'fly by the seat of my pants.' And, what is the worst that=20=
> can
> happen?=
terryh on thu 12 may 05
>>Don't know if this helps, but..... Got any sand in Dubai?
>>But now tell me again. You ran out of silica in the middle
>>of the desert???????
a good idea, but not all sands are silicate/feldspar.
many of beach sands in tropical regions are carbonate.
dubai on the gulf coast. you'd better check.
a drop of HCl solution will help :)
terry
terry hagiwara
terryh@pdq.net
http://www.geocities.com/terry.hagiwara
| |
|
