James Bledsoe on mon 17 jul 00
Richard, thanks for the info
We are using the local clay that can be wash out of the soil in Hesperia.
It is said to be an accent sea bed and as such i suspect there is a fair
amount of calcium and sodium mixed in with the clay. The soil color is
red/brown and what we suspect is was a fusion test [a dry tablespoon on a
flat tile fired to 2300f] melted it into a beautiful chocolate brown
semi-gloss and not runny. This is the base of the glaze/mortar. After
saying all that, How can we further analysis the soil base that our glaze
is being made from.
thanks
Jim
----- Original Message -----
From:
To:
Sent: Monday, July 17, 2000 1:01 PM
Subject: Hello, Fired structure in Hesperia and Local materials
> Hello Jim,
>
> Thank you for the address, those structures are exciting organic shapes.
> And thanks for the additional explanation of your dome.
>
> Raw borax can be used in waterproof glazes but high percentages may
> cause the following problems:
>
> 1. Borax can migrate to the surface of the ware creating a hard borax
> rich crust that can over flux and cause the glaze to run. Fast drying of
> the ware can help prevent this.
>
> 2. Borax can migrate into the clay body and cause over fluxing leading
> to black coring, slumping and bloating. On a thick brick this should be
> minimized. Again fast drying is helpful.
>
> 3. Borax releases gases as it melts causing the glaze surface to foam up
> increasing the glaze thickness by a considerable amount. This happens
> very early in the firing process and subsides after the gas is released.
>
> Fritting the borax by melting it with another glass or silica and clay
> can eliminate these problems in pottery.
>
> However clay bodies with high alkaline minerals like borax have been
> created on purpose because the glaze is built in to the body. Here slow
> drying causes the pot or brick to develop a thin glaze on the surface
> naturally. Soluble colorants, mostly metallic sulfates can be used in
> the body as well. An example of this is Egyptian Paste.
>
> http://ceramics.about.com/hobbies/ceramics/library/weekly/aa060198.htm
>
>
> Good luck,
> Keep us up to date.
>
> Richard Gilbert
> Cherryville North Carolina
>
>
____________________________________________________________________________
__
> 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.
>
rg42@BELLSOUTH.NET on mon 17 jul 00
Hello Jim,
Thank you for the address, those structures are exciting organic shapes.
And thanks for the additional explanation of your dome.
Raw borax can be used in waterproof glazes but high percentages may
cause the following problems:
1. Borax can migrate to the surface of the ware creating a hard borax
rich crust that can over flux and cause the glaze to run. Fast drying of
the ware can help prevent this.
2. Borax can migrate into the clay body and cause over fluxing leading
to black coring, slumping and bloating. On a thick brick this should be
minimized. Again fast drying is helpful.
3. Borax releases gases as it melts causing the glaze surface to foam up
increasing the glaze thickness by a considerable amount. This happens
very early in the firing process and subsides after the gas is released.
Fritting the borax by melting it with another glass or silica and clay
can eliminate these problems in pottery.
However clay bodies with high alkaline minerals like borax have been
created on purpose because the glaze is built in to the body. Here slow
drying causes the pot or brick to develop a thin glaze on the surface
naturally. Soluble colorants, mostly metallic sulfates can be used in
the body as well. An example of this is Egyptian Paste.
http://ceramics.about.com/hobbies/ceramics/library/weekly/aa060198.htm
Good luck,
Keep us up to date.
Richard Gilbert
Cherryville North Carolina
| |
|
