Steve Slatin on sun 2 mar 08
Heidy --
Why you are trying to sub for a glaze,
if you can get unity to match, you've already
matched Si/Al ratio, so that's not actually
much of an issue.
The rest is my opinion, others may differ --
In terms of getting things to melt well and
form a reliable, durable glaze, I find that
getting the Na plus K to match is important,
but whether you match by being high on one
and low on the other doesn't seem to be too
much of an issue as regards making glass.
It will be an issue in terms of expansion
(crazing, etc.) and color effect -- sodium
seems to give brighter colors than potassium,
generally speaking. So if you're concerned
with getting exactly a particular effect, get
unity right -- and use the same source
materials if possible, remembering that
particle size and every other darn thing
can make a difference -- and use the same
clay as was used in the model you're
trying to replicate, same firing etc.
Good luck -- Steve Slatin
Heidy Freyre wrote:
I tried to adapt the recipe to the materials I have available in Glaze
Master and got the following:
Feldspat Potash 35.3
Whiting 11.2
Frit F90167 7.8
Talc 9.7
Kaolin 11.1
Silica 24.9
Steve Slatin --
History teaches us that there have been but few infringements of personal liberty by the state which have not been justified ...
in the name of righteousness and the public good, and few which
have not been directed ... at politically helpless minorities.
-- Harlan Fiske Stone
---------------------------------
Never miss a thing. Make Yahoo your homepage.
Heidy Freyre on sun 2 mar 08
I tried to adapt the recipe to the materials I have available in Glaze
Master and got the following:
Feldspat Potash 35.3
Whiting 11.2
Frit F90167 7.8
Talc 9.7
Kaolin 11.1
Silica 24.9
Unity formula:
Na2O 0.084
K2O 0.163
MgO 0.195
CaO 0.558
Subtot alkalis 0.247
Al2O3 0.325
B2O3 0.051
Fe2O3 0.006
SiO2 2.778
TiO2 0.000
Si:Al 8.56 (exactly the same)
Exp. Coeff. 7.60
This did not withstand the simple lemon slice test and also run badly.
I then did a second version increasing alumina and silica:
Feldspat Potash 34.1
Whiting 10.8
Frit F90167 7.5
Talc 9.3
Kaolin 12.2
Silica 26.1
Unity formula:
Na2O 0.084
K2O 0.164
MgO 0.194
CaO 0.558
Subtot alkalis 0.248
Al2O3 0.340
B2O3 0.051
Fe2O3 0.007
SiO2 2.908
TiO2 0.000
Si:Al 8.56
Exp. Coeff. 7.48
I don=92t have the LOI for all my materials, so I don=92t mention it.
Firing schedule in electric kiln was:
60-120 C, 180-1094 C, 66-1215 C, 15 min hold, 260-1038 C, 66-820 C, end
The second recipe didn=92t run but pinholed, lemon test isn=92t done yet (j=
ust
out of the kiln)
So I would like to know which is more important:
To match as exactly as possible all the Unity figures or to match exactly
the Si:Al figure? (which I did in both cases) How much difference in the
alkali subtotal is acceptable?
I often have trouble to match the K2O and sometimes it just doesn=92t seem
possible even if I source from two different spars and frits at the same
time.
test tile pictures:
http://picasaweb.google.com/amapolablau/GlazeTestsMidfireGREENS
heidy
http://www.flickr.com/photos/amapolablau/sets
Donna Kat on sun 2 mar 08
You might consider Ron Roy's revision of that glaze. It is really lovely.
http://www.frogpondpottery.com/glazestability/glaze0024.html
Donna
John Post on sun 2 mar 08
Heidy,
I was looking at the glaze tiles you have posted on Picasa. Do you
have the recipes for these posted anywhere? It would be interesting
to see what ingredients you used to achieve some of the colors and
textures I see on your tiles.
John Post
Sterling Heights, Michigan
http://www.johnpost.us :: cone 6 glaze website ::
http://www.wemakeart.org :: elementary art website ::
Heidy Freyre on mon 3 mar 08
John,
Yes I have everything in my Glaze Master. Just tell me which ones you would
like to know about and I will be glad to mail you recipes, analysis and
material analysis.
Most recipes are from Clayart or the Bailey book. But I often have trouble
with my materials in getting to the unity formula given. But then I am just
a newbie trying to learn glaze formulation on my own.
heidy
On Sun, 2 Mar 2008 18:40:47 -0500, John Post
wrote:
>Heidy,
>I was looking at the glaze tiles you have posted on Picasa. Do you
>have the recipes for these posted anywhere? It would be interesting
>to see what ingredients you used to achieve some of the colors and
>textures I see on your tiles.
>
>
>John Post
>Sterling Heights, Michigan
>http://www.johnpost.us :: cone 6 glaze website ::
>http://www.wemakeart.org :: elementary art website ::
>
>___________________________________________________________________________
___
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here:
http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
melpots2@visi.com
Heidy Freyre on tue 4 mar 08
Thank you Donna, I hadn't seen this one.
heidy
On Sun, 2 Mar 2008 18:09:42 -0500, Donna Kat wrote:
>You might consider Ron Roy's revision of that glaze. It is really lovely.
>
>http://www.frogpondpottery.com/glazestability/glaze0024.html
>
>Donna
>
>___________________________________________________________________________
___
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here:
http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
melpots2@visi.com
| |
|
