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sodium silicate over engobe

updated fri 14 oct 05

 

Paula Mann on wed 15 jun 05


After having taken a sphere throwing workshop and seeing what sodium =
silicate did when painted lightly on Soldate 80 before shaping, I had to =
try some of my own experiments.

The spheres we prepared in the workshop were intended to be saggar =
fired.

I have many questions now. The instructor mentioned that the SS could =
be painted over engobe. I envisioned a nice, white porcelain with black =
engobe and the SS creating those beautiful crevices and fissures with =
black and white.

Well, after throwing, the cracks are quite amazing, but the SS seems to =
"slide" down the porcelain body and stiffen up. That wasn't the case on =
the Soldate, the SS stayed where it was put.

I have the pieces covered with plastic but I'm afraid there's no way =
I'll be able to trim them (unfortunately I didn't throw them to be =
untrimmed).

I'm also wondering if firing to cone 5 will cause some wretched reaction =
between the clay and the SS. Isn't saggar firing generally at fairly =
low temperatures?

I always hesitate to post my questions because they seem so stupid but =
it never fails that I get 4 or 5 great answers that really help.

Clayart is great!!!

Paula
Ft. Collins, Co

Eric Serritella on thu 13 oct 05


I've used SS on stoneware and porcelain with thick and thin slips from cone
6 oxidation to cone 10+ wood firing. I do find that it will run on
porcelain, especially if I've first cleaned the outside of the pot with a
metal rib. I apply it thin in that case to avoid drips. Have never had
cracks exaggerate during firing. Pretty much what I see is what I get.
Hopefully that will give you confidence to try to fire to cone 5.

As far as the bottom goes, I find that most of the cracking as at the
surface unless I really push the clay to expand after applying (which is
really cool to do). So you might be able to just trim away where it has run
and cracked the bottom. In other words, trim away the cracked area down to
solid clay.

Good luck.
Eric


Muddy Paws Pottery
528 Sebring Road
Newfield, NY 14867
607.564.7810
www.muddypawspottery.com

----- Original Message -----
From: "Ama Menec"
To:
Sent: Wednesday, October 12, 2005 8:08 PM
Subject: Re: Sodium Silicate Over Engobe


> Hi Paula,
>
> Did you get any useful replies to this question? I've never heard of this
> technique before. Please do share what you came up with. Best wishes,
>
> Ama Menec, Totnes, Devon, UK.
> Email: amamenec@lineone.net
>
> ----- Original Message -----
> From: "Paula Mann"
> To:
> Sent: Thursday, June 16, 2005 12:06 AM
> Subject: Sodium Silicate Over Engobe
>
>
> After having taken a sphere throwing workshop and seeing what sodium
> silicate did when painted lightly on Soldate 80 before shaping, I had to
try
> some of my own experiments.
>
> The spheres we prepared in the workshop were intended to be saggar fired.
>
> I have many questions now. The instructor mentioned that the SS could be
> painted over engobe. I envisioned a nice, white porcelain with black
engobe
> and the SS creating those beautiful crevices and fissures with black and
> white.
>
> Well, after throwing, the cracks are quite amazing, but the SS seems to
> "slide" down the porcelain body and stiffen up. That wasn't the case on
the
> Soldate, the SS stayed where it was put.
>
> I have the pieces covered with plastic but I'm afraid there's no way I'll
be
> able to trim them (unfortunately I didn't throw them to be untrimmed).
>
> I'm also wondering if firing to cone 5 will cause some wretched reaction
> between the clay and the SS. Isn't saggar firing generally at fairly low
> temperatures?
>
> I always hesitate to post my questions because they seem so stupid but it
> never fails that I get 4 or 5 great answers that really help.
>
> Clayart is great!!!
>
> Paula
> Ft. Collins, Co
>
>
____________________________________________________________________________
> __
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>
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> melpots@pclink.com.
>
>
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____________________________________________________________________________
__
> 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.
>

Paula Mann on thu 13 oct 05


It was a surprise to get a response to my question (posted in June) about
sodium silicate but since I did (my apologies, Ama, for not responding to
you, I didn't see your post) I thought I'd send a follow up.

I did get the porcelain pieces off the bat and trimmed. It wasn't as tough
as I thought it would be. I fired to cone 5, as planned. The black engobe
turned a sort of deep greenish color but I attribute that to the clay (Frost
porcelain) which seems to change the color of engobes as well as glazes.
Still, the effect was very cool with deep white fissures in the black.

I find that stretching the clay considerably while shaping gives some great
texture, but not as dramatic as adding sodium silicate.

Paula Mann
Fort Collins, CO

Ama Menec on thu 13 oct 05


Hi Paula,

Did you get any useful replies to this question? I've never heard of this
technique before. Please do share what you came up with. Best wishes,

Ama Menec, Totnes, Devon, UK.
Email: amamenec@lineone.net

----- Original Message -----
From: "Paula Mann"
To:
Sent: Thursday, June 16, 2005 12:06 AM
Subject: Sodium Silicate Over Engobe


After having taken a sphere throwing workshop and seeing what sodium
silicate did when painted lightly on Soldate 80 before shaping, I had to try
some of my own experiments.

The spheres we prepared in the workshop were intended to be saggar fired.

I have many questions now. The instructor mentioned that the SS could be
painted over engobe. I envisioned a nice, white porcelain with black engobe
and the SS creating those beautiful crevices and fissures with black and
white.

Well, after throwing, the cracks are quite amazing, but the SS seems to
"slide" down the porcelain body and stiffen up. That wasn't the case on the
Soldate, the SS stayed where it was put.

I have the pieces covered with plastic but I'm afraid there's no way I'll be
able to trim them (unfortunately I didn't throw them to be untrimmed).

I'm also wondering if firing to cone 5 will cause some wretched reaction
between the clay and the SS. Isn't saggar firing generally at fairly low
temperatures?

I always hesitate to post my questions because they seem so stupid but it
never fails that I get 4 or 5 great answers that really help.

Clayart is great!!!

Paula
Ft. Collins, Co

____________________________________________________________________________
__
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.


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Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.14/131 - Release Date: 12/10/05