Corinne Null on wed 20 nov 96
Thought I'd seen some posts alluding to how the bisquing might later affect
the glaze firing. Could someone illuminate this area for me? I'm not sure
I "get it".
I do get that the glaze has to match in expansion to the clay, whether its a
single fire, or bisque fired piece. Think I've been hearing other affects
though, or am I just halucinating? :)
Corinne Null
Bedford, NH
cnull@mv.mv.com
Bob Hanlin on thu 21 nov 96
Corrine:
If the bisque is too hard (fired too high" it won't absorb enough water from
the glaze to make a thick enough coating for the glaze to do what you want
it to.
>----------------------------Original message----------------------------
>Thought I'd seen some posts alluding to how the bisquing might later affect
>the glaze firing. Could someone illuminate this area for me? I'm not sure
>I "get it".
>
>I do get that the glaze has to match in expansion to the clay, whether its a
>single fire, or bisque fired piece. Think I've been hearing other affects
>though, or am I just halucinating? :)
>
>Corinne Null
>Bedford, NH
>
>cnull@mv.mv.com
>
>
Bob Hanlin
3504 N. Tulsa
Oklahoma City, OK 73112
e-mail bhanlin@ionet.net
Bugash@aol.com on thu 21 nov 96
I'm a new potter so am no expert by any means but one thing I just discovered
is that the temperature you bisque at can effect whether or not you get
blisters. A test I just did had blisters all over it which were caused by
out-gasing. I was told that if I had bisqued at a higher temp. this wouldn't
have happened. I'm re-bisquing my tiles to check this out.
Tony Hansen on sat 23 nov 96
> I just discovered that the temperature you bisque at can effect whether or not
> blisters. A test I just did had blisters all over it which were caused by
> out-gasing.
It is not how high you bisque but how slow the firing is through the
700-900C range where volatiles are burned away. It is also dependent on
whether the kiln atmosphere is clean and oxidizing and whether each
piece is getting good ventilation and air flow.
--
Tony Hansen, IMC - Pulishers of INSIGHT, FORESIGHT, Magic of Fire
134 Upland Dr., Medicine Hat, Alta T1A 3N7 Canada
Phone:403-527-2826 FAX:527-7441 email: thansen@mlc.awinc.com
web: http://digitalfire.com/imc.html
Richard Burkett on sun 24 nov 96
Tony Hansen says:
>It is not how high you bisque but how slow the firing is through the
>700-900C range where volatiles are burned away. It is also dependent on
>whether the kiln atmosphere is clean and oxidizing and whether each
>piece is getting good ventilation and air flow.
While this is good advice, it may not result in all the sulfur compounds
being burned out, and these are often the cause of glaze defects. Bisque
firing to the cone 05 or above range will greatly aid removal of sulfur
compounds. Many of these compounds do not burn out completely at cone 07-06
or lower bisque temperatures. Care must be taken not to bisque too high so as
to make the ware too dense and glazing difficult.
To complicate this further, some sulfur compounds do not easily volatilize
early in the firing until they are first reduced, then reoxidized. While
reducing bisqueware is not generally recommended, if you are firing the ware
in a gas reduction firing you may want to do the so called "body reduction"
followed by a period of oxidation before beginning reduction for the glazes
at about cone 06-05.
If you're firing in oxidation, your best bet may be to switch to low-sulfur
clays. This may also be a good idea from an environmental standpoint no
matter how you fire your ware, as sulfur dioxide is a highly noxious gas.
Richard Burkett - School of Art, Design, & A.H, SDSU, San Diego, CA 92182-4805
E-mail: richard.burkett@sdsu.edu <-> Voice mail: (619) 594-6201
Home Page: http://rohan.sdsu.edu/dept/rburkett/www/burkett.html
CeramicsWeb: http://apple.sdsu.edu/ceramicsweb/index.html
Edgeworth Barnes on sun 24 nov 96
Bob Hanlin wrote:
>
> ----------------------------Original message----------------------------
> Corrine:
> If the bisque is too hard (fired too high" it won't absorb enough water from
> the glaze to make a thick enough coating for the glaze to do what you want
> it to.
>
> >----------------------------Original message----------------------------
> >Thought I'd seen some posts alluding to how the bisquing might later affect
> >the glaze firing. Could someone illuminate this area for me? I'm not sure
> >I "get it".
> >
> >I do get that the glaze has to match in expansion to the clay, whether its a
> >single fire, or bisque fired piece. Think I've been hearing other affects
> >though, or am I just halucinating? :)
> >
> >Corinne Null
> >Bedford, NH
> >
> >cnull@mv.mv.com
> >
> >
> Bob Hanlin
> 3504 N. Tulsa
> Oklahoma City, OK 73112
>
> e-mail bhanlin@ionet.netYou will find that bisquing too high will inhibit the
(smoke) the pots will take on in post-firing reduction on raku.
Also, if you are burnishing pieces to be bisqued and later pit or smoke
fired, bisquing should be 08 or lower to maintain the sheen of
burnishing. Firing higher will result in loss of sheen.
Jean Lehman on mon 25 nov 96
If you are using a commercial clay, will a clay manufacturer (such as
Standard Ceramics) give us that information???
Jean
j_lehman@acad.FandM.EDU (that's an _underscore_ not a hyphen)
>----------------------------Original message----------------------------
>
>If you're firing in oxidation, your best bet may be to switch to low-sulfur
>clays. This may also be a good idea from an environmental standpoint no
>matter how you fire your ware, as sulfur dioxide is a highly noxious gas.
>
>Richard Burkett - School of Art, Design, & A.H, SDSU, San Diego, CA 92182-4805
>E-mail: richard.burkett@sdsu.edu <-> Voice mail: (619) 594-6201
>Home Page: http://rohan.sdsu.edu/dept/rburkett/www/burkett.html
>CeramicsWeb: http://apple.sdsu.edu/ceramicsweb/index.html
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