Snail Scott on fri 23 jan 04
At 10:06 AM 1/23/04 -0500, you wrote:
>Is there a general rule of thumb for bringing a ^6 glaze recipe to something
>that works well at ^8?
Just reduce the flux(es) a bit, 'til you like the look.
>
>And how come, anyway, everyone is so keen on ^6?
It's a good compromise between the durability of a
higher-fired stoneware and the reduced demands of
lower firing temperatures. Below mid-range, you have
to be more finicky in glaze design and fewer materials
are naturally convenient, and clay bodies become
progressively less hard and vitreous. Above mid-range,
there is a sharp increase in wear and tear on a kiln.
If everyone fired with fuel, the difference would be
less apparent, but the lifespan of electric elements
makes the distinction clearer. The rising popularity
of mid-range stoneware, I think, is driven by the
electric-kiln branch of ceramics. (Also, it takes a
well-designed kiln with good-quality refractories to
make a good ^10 kiln, fuel OR electric. A ^6 kiln is
less demanding in design and construction. Excellence
is still desirable, but less essential.
Why ^6 as opposed to ^5 or some such? It's a pretty
narrow range, after all, and it seems like over the
last few years, the general '^4-^6' range has narrowed
to a distinct bias toward ^6 specifically. There is
a desire, I think, for standardization, which allows
for the popularization of specific commercial clay
bodies and for glaze-recipe swapping. Many people still
do ^4 or ^5 (just as some people prefer ^9 or ^11 to
the conventional ^10), and since practical firing
ranges of materials often will accomodate this, these
people also benefit from the general 'mid-range' trend,
but many people like the assurance and ease of being
able to pick from a selection of compatible, standard
clays and glazes. Just as VHS edged out Betamax, ^6 is
edging out the other mid-range temperatures mainly
by force of numbers: once one temperature has a large
enough following, its popularity will increase even
more rapidly.
After a stint in the (then-)semi-obligatory world of
academic ^10 reduction, I switched to ^4, for the
perceived advantages of less stress on the clay and
a wider color palette, as well as a reduced need to
optimize kiln design in order to reach the desired
temperature. Since every 'scratch' glaze recipe needs
some tweaking anyway, and since enough recipes were
at least 'in the ballpark' to start, (less bias
toward only ^6 back then), there was no strong reason
to go with a particular temperature within the mid-
fire range. I picked ^4 specifically because it was
the best firing temperature for a clay recipe I'd
developed, with proportions which were easy to measure
by volume (an advantage that would be lost if I had
tweaked it to another temperature), and it was suitable
to my work. I switched to ^6 later, when I switched to
oxidation firing - my high-iron body needed the extra
heat-work to vitrify without the fluxing action of a
reduction atmosphere, and I relied more on my clay than
my glazes to create my work. The fact that the rest of
the world has widely come around to that temperature
also is just a handy coincidence for me. ;)
-Snail
Nana Underhill on fri 23 jan 04
I apologize if this is in the archives already. I had no luck slogging
through it this morning.
Is there a general rule of thumb for bringing a ^6 glaze recipe to something
that works well at ^8? Is it just a matter, generally of giving it a higher
melting point, or are there other things to consider as well?
And how come, anyway, everyone is so keen on ^6? (Never having had control
of my own kiln, I haven't had a chance to experience it for myself.)
Thanks,
Nana
Ababi on sat 24 jan 04
Hello Nana
It is very simple yet very hard:
The simplest way is to add kaolin.
How much?
Test:
Will the glaze be the same- I doubt it- silica is needed too.
What kind of glaze you need?
If it would be that easy we could dump all the software we use I think
we should call them "smartware".
If there is a particular recipe you can send me and I can try - but the
tests you must do yourself.
About ^6:
This is the minimal ^ to have strong reliable wares. In this case you
save your money. Try to see how much energy you save in reducing the
heating time and the life of the spirals.
My kiln is made for 1300C ^10 I fire to ^6 lately two spirals passed
away after 5 years of using.
If I would fire higher must of happen earlier!
Another point: this ^6 become a language: It is very easy TO FIND ANY
RECIPE FOR ^6 YET IT IS HARDER TOD ONE FOR^8.
Keep glazing!
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://ababi.active.co.il
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
-----Original Message-----
From: Clayart [mailto:C
LAYART@LSV.CERAMICS.ORG] On Behalf Of Nana Underhill
Sent: Friday, January 23, 2004 5:07 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: ^6 to ^8
I apologize if this is in the archives already. I had no luck slogging
through it this morning.
Is there a general rule of thumb for bringing a ^6 glaze recipe to
something
that works well at ^8? Is it just a matter, generally of giving it a
higher
melting point, or are there other things to consider as well?
And how come, anyway, everyone is so keen on ^6? (Never having had
control
of my own kiln, I haven't had a chance to experience it for myself.)
Thanks,
Nana
________________________________________________________________________
______
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
logan johnson on sun 25 jan 04
Hi Nana,
I can' help you with the first part of your question BUT, I can tell you why I go to ^6
instead of going higher. $$$$$$$$ . It was easier to afford the kiln, Cone six is less expensive for ME to fire to than ^10
I fire in oxidation so the electric bill is a big concern. My hubby has built me a ^10 GAS
kiln but the shed to protect it isn't finished yet. So, since the kiln will be fired outside, it's still ^6ox indoors for me. Also it's less effort on my part to do the actual firing process.
No checking the cones, no messing withn reduction process ect. I will be doing all that soon (fingers crossed) but, when I FIRST started all that was too much for ME to have to remember when combined with just learning to make the clay do what I wanted it to do .
I wanted to focus on the clay. Then, I learned that many people made an acceptable & professional living from ^6 & that's all it took . Some people may say this was the lazy
way to go But I was not comfortable with gas at first. If I'm going to do something that makes my soul sing I can't see why I should make myself uncomfortable doing it.
HOPE THIS HELPS!!! Best of luck!!
Nana Underhill wrote:
And how come, anyway, everyone is so keen on ^6? (Never having had control
of my own kiln, I haven't had a chance to experience it for myself.)
Thanks,
Nana
______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Logan Johnson Audeo Studios
www.audeostudios.com
"Carpe Argillam!!"
Ron Roy on wed 28 jan 04
Hi Nana,
My rule is - add clay and silica - keeping the ratio of SiO2 to Al2O3 the
same - you should use calculation software to do this - or - if you have
the skill and time - calculate the Seger Unity Formula by hand.
If you do a line blend increasing Kaolin by 2% each time - adding 2.5% of
Silica to keep the ratio the same.
I can't give you numbers for ball clays because they differ so much.
The other part is to watch the calculated expansion as you do this - it
will go down - if it goes down too far then raise it back up by adding some
KNaO at the expence of some of the fluxing oxides that have lower expansion
rates.
If you don't want the surface to be as shiny then just add the clay - if
you want the surface to be more shiny add 3 or 4% of silica for every 2 of
Kaolin.
Just remember - adding silica is a recognized way to lower expansion - if
the expansion is already low you may get dunting and/or shivering so test
for that.
RR
>>I apologize if this is in the archives already. I had no luck slogging
>>through it this morning.
>>
>>Is there a general rule of thumb for bringing a ^6 glaze recipe to something
>>that works well at ^8? Is it just a matter, generally of giving it a higher
>>melting point, or are there other things to consider as well?
>>
>>And how come, anyway, everyone is so keen on ^6? (Never having had control
>>of my own kiln, I haven't had a chance to experience it for myself.)
>>
>>Thanks,
>>
>>Nana
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
| |
|
