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soda ash question

updated fri 26 nov 04

 

John Palmquist on tue 23 nov 04


Hi experts!
I have put a soda wash on a few my pots and fired them in my =
electric kiln. I was told by another potter that it would ruin my kiln =
elements. Any thoughts on this?
Thanks for the response.Hope everyone has a great Thanksgiving.
Diane

Marcia Selsor on tue 23 nov 04


Dannon Rhudy had a nice wash for electric kiln...soda ash with 5%
rutile. I don't think it destroyed anything.
Marcia Selsor
On Nov 23, 2004, at 7:51 AM, John Palmquist wrote:

> Hi experts!
> I have put a soda wash on a few my pots and fired them in my
> electric kiln. I was told by another potter that it would ruin my kiln
> elements. Any thoughts on this?
> Thanks for the response.Hope everyone has a great Thanksgiving.
> Diane
>

Diane Palmquist on tue 23 nov 04


Thanks for the response dabao. I am firing to cone six in my
electric -so I am assuming that this is a high enough temp. to decompose?
Diane
----- Original Message -----
From: "Bao Da"
To:
Sent: Tuesday, November 23, 2004 1:39 PM
Subject: Re: soda ash question


> I think I can give an answer to your question. Soda can decompose to
carbon dioxide and sodium oxide at higher temperatures. If the temperature
in the kiln is higher enough, sodium oxide can even decompose to sodium
vapor and oxygen. As we all know that sodium vapor can react with so many
substances, which also include some elements in you kiln.
>
> best regards
>
> dabao
>
> John Palmquist wrote:
> Hi experts!
> I have put a soda wash on a few my pots and fired them in my electric
kiln. I was told by another potter that it would ruin my kiln elements. Any
thoughts on this?
> Thanks for the response.Hope everyone has a great Thanksgiving.
> Diane
>
>
____________________________________________________________________________
__
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melpots@pclink.com.
>
>
>
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Eva Gallagher on tue 23 nov 04


Hi John,
I have used soda ash to darken any unglazed parts of my brown clay - it
gives it a warm toasty colour. I sometimes use the clear water on settled
ash glases as well as it does the same thing but better. Some glazes contain
soda ash - and ash glazes would contain soda ash naturally (I think.)
Settlers would use ashes to leach out the soda ash (or something chemically
very similar I think) and use it for soap making.
So far have not seen any detrimental effects - perhaps if you use a thick
coating it might vaporise and damage elements?
Regards,
Eva Gallagher
Deep River, Ontario


----- Original Message -----
From: "John Palmquist"
To:
Sent: Tuesday, November 23, 2004 9:51 AM
Subject: soda ash question


Hi experts!
I have put a soda wash on a few my pots and fired them in my electric
kiln. I was told by another potter that it would ruin my kiln elements. Any
thoughts on this?
Thanks for the response.Hope everyone has a great Thanksgiving.
Diane

____________________________________________________________________________
__
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.

Kate Johnson on tue 23 nov 04


> Settlers would use ashes to leach out the soda ash (or something
> chemically
> very similar I think) and use it for soap making.

I know that as lye...is soda ash the same thing? I've actually made soap
that way, what a mess! (These old back-to-the-land types are likely to have
tried EVERYTHING, I'm surprised I wasn't into pottery then. Would have been
a great place for a big old raku firing or saggar or something...)

Best--
Kate

Eva Gallagher on tue 23 nov 04


Hi Kathy -
Sorry to mislead everyone - I should check my facts and not just my memory.
Soda ash is sodium carbonate and lye is sodium hydroxide - not same thing.
So soda ash does not come from wood ashes, but it is called that as one time
it was produced from seaweed ashes. It is still used in making soap, I guess
as a substitute in part for lye.
Eva
Deep River, Ontario

----- Original Message -----
From: "Kate Johnson"
To:
Sent: Tuesday, November 23, 2004 8:13 PM
Subject: Re: soda ash question


> > Settlers would use ashes to leach out the soda ash (or something
> > chemically
> > very similar I think) and use it for soap making.
>
> I know that as lye...is soda ash the same thing? I've actually made soap
> that way, what a mess! (These old back-to-the-land types are likely to
have
> tried EVERYTHING, I'm surprised I wasn't into pottery then. Would have
been
> a great place for a big old raku firing or saggar or something...)
>
> Best--
> Kate
>
>
____________________________________________________________________________
__
> 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.

Louis Katz on tue 23 nov 04


Lye-Sodium Hydroxide
Soda Ash- Sodium Carbonate
To make soap oil and fat is heated with sodium hyroxide or pottasium
hydroxide or a mixture. Sodium Oleates and Stearates result. (Maybe
someone has more details here). These compounds are what we call soap.
On the same sort of topic
Sodium oleates and stearates are miscible (mixable) with water.
When you apply mold soap to a mold, calcium replaces the sodium. The
compounds become calcium stearates and oleates. These do not mix with
water. They act as a separator and sealant on the mold. They are know
to the non-clayer world (muggles) as soap scum.

Lye is very nasty stuff. Watch out for it. It will eat your skin,
quickly destroy your eyes, don't get it in your mouth. Goggles,
appropriate gloves rubber apron etc. if it is concentrated or dry.
Anyone thinking of using lye powdered in glazes should think again. A
wood ash glaze that has dried to mud may have a serious concentration
of lye in it.

To extract lye from wood ash, burn the ash in a cool fire (not your
stoneware kiln, the soda all volitalizes)
place it in an old close woven sack
lit water drip onto the ash one drop at a time and collect the
concentrated solution when it starts to emerge from the bottom of the
bag.
Get it in your eye and your sight is probably history. It will burn
your skin.

I believe that soda ash is a byproduct of chlorine production from
salt, but am not sure.
Louis

On Nov 23, 2004, at 7:13 PM, Kate Johnson wrote:

>> Settlers would use ashes to leach out the soda ash (or something
>> chemically
>> very similar I think) and use it for soap making.
>
> I know that as lye...is soda ash the same thing? I've actually made
> soap
> that way, what a mess! (These old back-to-the-land types are likely
> to have
> tried EVERYTHING, I'm surprised I wasn't into pottery then. Would
> have been
> a great place for a big old raku firing or saggar or something...)
>
> Best--
> Kate
>
> _______________________________________________________________________
> _______
> 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.
>
>
Louis Katz
WIKI site http://www.tamucc.edu/wiki/Katz/HomePage

Ivor and Olive Lewis on wed 24 nov 04


Dear Diane,
When someone puts a negative spin like that on something you intend
doing you might ask them to give the origin of their assertion and
explain the science that underpins their objections.
Given the chemical reaction between Sodium carbonate and Silica
releases Carbon dioxide, a gas that is relatively inert towards
metallic oxides and knowing the quantity involved is very low I can
see no reason for curtailing trials of your work in this way.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.

Ivor and Olive Lewis on wed 24 nov 04


Dear Bao Da,
Perhaps you can tell us the temperature at which each of these
substances (Sodium Carbonate and Sodium Oxide ) decompose ?.
It is said Sodium chloride decomposes during the salt glaze reaction,
yet the chemical tables give the melting point of that compound as
801=BA C and the boiling point as 1413=BA C. My calculation of the
dissociation temperature was over 2500=BA C (or if you wish ~4500=BA F.),
a little bit above the usual firing temperature in this process
Durrant explains the reaction between Sodium Carbonate and Silica with
the formation of Sodium Silicate once the alkali has melted.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.

daniel on wed 24 nov 04


Hi Ivor,

I've been reading on the melting of glazes lately, and came aross the
following in Parmelee and Harman. In the discussion of dissociation, early
in Ch 6 Conversion of the Batch to the Glaze, they state that decomposition
temperatures can be altered significantly by the presence of impurities. The
example they quote relates to pure dolomite which they say decomposes in two
steps :

CaCO3.MgCO3 -> CaCO3 + MgO + CO2 at 780C
CaCO3 -> CaO + CO2 at 900C

Aparently the first reaction may occur 630C if 5% Na2CO3 or K2CO3 is
present.

I do not, in the case of sodium carb, or salt), know whether similar things
might also occur ?

Just tossing it out there to see if it helps.

> It is said Sodium chloride decomposes during the salt glaze reaction,
> yet the chemical tables give the melting point of that compound as
> 801锟 C and the boiling point as 1413锟 C. My calculation of the
> dissociation temperature was over 2500锟 C (or if you wish ~4500锟 F.),
> a little bit above the usual firing temperature in this process

Thanx
D

Belmont, California, USA
(ex terra australis)

Bao Da on wed 24 nov 04


I think I can give an answer to your question. Soda can decompose to carbon dioxide and sodium oxide at higher temperatures. If the temperature in the kiln is higher enough, sodium oxide can even decompose to sodium vapor and oxygen. As we all know that sodium vapor can react with so many substances, which also include some elements in you kiln.

best regards

dabao

John Palmquist wrote:
Hi experts!
I have put a soda wash on a few my pots and fired them in my electric kiln. I was told by another potter that it would ruin my kiln elements. Any thoughts on this?
Thanks for the response.Hope everyone has a great Thanksgiving.
Diane

______________________________________________________________________________
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.



---------------------------------
Do You Yahoo!?
150万曲MP3疯狂搜,带您闯入音乐殿堂
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1G就是1000兆,雅虎电邮自助扩容!

Ivor and Olive Lewis on thu 25 nov 04


Dear Daniel,
I would suggest that, in the case of the low decomposition temperature
of Dolomite, the Alkali metal carbonates may be having a catalytic
effect.
I would agree with Parmellee and Harman that small concentrations of
impurities can have remarkable effects in some systems. In particular,
the effect of interstitial inclusions existing in solid solutions is
well known and documented by Kingery et al.
Kay and Laby give 350=C2=BA C as the decomposition temperature of Magnesi=
um
Carbonate and for one form of Calcium Carbonate, 825=C2=BA C.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.