Numo Jaeger and Michael Miller on tue 24 feb 98
Hello ClayArt Folks,
I have a student who has a slip glaze which she made from clay she got in
the midwest.
The consistancy of the slip glaze is very much like a terra sig. It worked
fairly well on greenware. It is a soft brownish, rust color after it is
fired. We do not know the actually composition of the clay though.
Recently she tried to put this slip glaze on several pieces of bisque ware.
She dipped the pieces in the slip but even though the application was
rather thin it cracked off. (This made sense to me since it is a clay.)
My question is:
Does anyone have any suggestions for application of this slip glaze so it
doesn't peal off?
Numo Jaeger
Studio One Art Center
365 45th Street
Oakland, CA 94606
E-mail:jaegmil@wenet.net
McCoy, Jack Eugene on wed 25 feb 98
To keep slip glazes from peeling off you might try:
1) Applying the slip to greenware. This way the clay body and the
clay-based glaze shrinks at simliar rates while drying.
2) Calcinating the clay in the slip. This reduces the size of the clay
particles, and thus reduces the shrinkage in the glaze while drying.
I've done number 1, but haven't gone through the trouble of firing
containers of powdered clay as in number 2. Perhaps some of the
experts on the list can shed more light on the problem.
Jack
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=-=-=-=-=
Jack McCoy
Systems Programmer
East Carolina University
Voice: (919) 328-6855
Fax: (919) 328-4258
email: mccoyj@mail.ecu.edu
> ----------
> From: Numo Jaeger and Michael Miller[SMTP:jaegmil@wenet.net]
> Reply To: Ceramic Arts Discussion List
> Sent: Tuesday, February 24, 1998 7:51 AM
> To: Multiple recipients of list CLAYART
> Subject: Re: Slip glaze that slipped off
>
> ----------------------------Original
> message----------------------------
> Hello ClayArt Folks,
>
> I have a student who has a slip glaze which she made from clay she got
> in
> the midwest.
>
> The consistancy of the slip glaze is very much like a terra sig. It
> worked
> fairly well on greenware. It is a soft brownish, rust color after it
> is
> fired. We do not know the actually composition of the clay though.
>
> Recently she tried to put this slip glaze on several pieces of bisque
> ware.
> She dipped the pieces in the slip but even though the application was
> rather thin it cracked off. (This made sense to me since it is a
> clay.)
>
> My question is:
>
> Does anyone have any suggestions for application of this slip glaze so
> it
> doesn't peal off?
>
> Numo Jaeger
> > Studio One Art Center
> 365 45th Street
> Oakland, CA 94606
>
> E-mail:jaegmil@wenet.net
>
paul wilmoth on wed 25 feb 98
Numo,
When you use clay as a glaze ingredient shrinkage can be a
problem.
It is easy to fix. You need to calcine a portion of the clay and that
will reduce the shrinkage. Many times as little as 5 to 10 % is all that
is needed from the total clay content in the glaze. I have placed the dry
powdered clay into a bisqued bowl and fired it in another bisque firing.
This process will drive off water that is physically and chemically
combined with the clay and will stop the shrinkage during drying. If you
calcine too much the glaze may be difficult to keep in suspension.
Because you are driving off water (that is part of what you are
weighing when you mix the glaze) you may need to reduce the total content
of the clay to get the same finished results. Weigh the dry clay that you
put into the kiln before and after calcining. This will tell you the
weight of water that has been driven off. If you put 10 lbs of dry clay
into the kiln and after calcining it weighs 8 lbs then you have reduced
the weight by 20%. Therefore decrease the amount of calcined clay 20%
and you should get the same final fired result.
good luck - Paul
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rballou@mnsinc.com on wed 25 feb 98
Also try applying to leather hard, as you would a slip. You may want to
thicken the glaze for this. Usually an addition of 4 - 8% bentonite will
solve any application problems for leather hard.
>----------------------------Original message----------------------------
>To keep slip glazes from peeling off you might try:
>
>1) Applying the slip to greenware. This way the clay body and the
>clay-based glaze shrinks at simliar rates while drying.
>
>2) Calcinating the clay in the slip. This reduces the size of the clay
>particles, and thus reduces the shrinkage in the glaze while drying.
>
>I've done number 1, but haven't gone through the trouble of firing
>containers of powdered clay as in number 2. Perhaps some of the
>experts on the list can shed more light on the problem.
>
>Jack
>
>
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>=-=-=-=-=
>Jack McCoy
>Systems Programmer
>East Carolina University
>Voice: (919) 328-6855
>Fax: (919) 328-4258
>email: mccoyj@mail.ecu.edu
>
>
>> ----------
>> From: Numo Jaeger and Michael Miller[SMTP:jaegmil@wenet.net]
>> Reply To: Ceramic Arts Discussion List
>> Sent: Tuesday, February 24, 1998 7:51 AM
>> To: Multiple recipients of list CLAYART
>> Subject: Re: Slip glaze that slipped off
>>
>> ----------------------------Original
>> message----------------------------
>> Hello ClayArt Folks,
>>
>> I have a student who has a slip glaze which she made from clay she got
>> in
>> the midwest.
>>
>> The consistancy of the slip glaze is very much like a terra sig. It
>> worked
>> fairly well on greenware. It is a soft brownish, rust color after it
>> is
>> fired. We do not know the actually composition of the clay though.
>>
>> Recently she tried to put this slip glaze on several pieces of bisque
>> ware.
>> She dipped the pieces in the slip but even though the application was
>> rather thin it cracked off. (This made sense to me since it is a
>> clay.)
>>
>> My question is:
>>
>> Does anyone have any suggestions for application of this slip glaze so
>> it
>> doesn't peal off?
>>
>> Numo Jaeger
>> >> Studio One Art Center
>> 365 45th Street
>> Oakland, CA 94606
>>
>> E-mail:jaegmil@wenet.net
>>
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