Bisque

[Benhim]

Can anyone give me a good reason why they fire their bisque all the way up to cone 03? I've seen many posts referencing cone 03 as a bisque temperature. I was taught to fire to cone 08, and a few people I know fire to cone 010 because it works better with their glazes. I do cone 08 because anything less is very fragile. 03 however seems like over kill, am I missing something here?

[clay lover]

All I know is what I do, so take this with that in mind. When I was firing to ^06, the pots came out of the glaze firing with pin holes often and glaze runs and drip marks. After I increased to ^05, 1910*, that all stopped and the pots looked better.

I think the bisque temp has to do with how much glaze adhears to the pots, because when people have mistakenly fired a bisque load to their glaze temp, they say the glaze justs runs off the pots. The clay is so 'tight' it won't absord the glaze slurry. I don't know what temp that starts at,.

[Chris Campbell]

Bisque firing is so misunderstood and often badly taught by teachers who love to hand out RULES. From what I have read, bisque firing started out as a convenience thing to cut down on breakage ... ? .... Now it is thought to be a good way to out gas pots and get rid of impurities that could later affect glaze results.

There is no rule for temperature. It all depends on your clay and what you are going to do next.

The cooler the bisque firing the softer and more open your clay body will be. When I need to sand my pieces I bisque at cone 010. For things like raku and pit firing, a soft open clay body is wonderful for capturing all those colors so bisque tends to be low 08 - 06 ish. Most cone 6 clay bodies that are going to be glazed do well slow bisque fired anywhere between 08 - 06. Some people like 04 because not as much glaze gets absorbed ... others dont like it for the same reason and use 06. My porcelain gets bisque fired to cone 9.

So open yourself up to thinking about what you are going to do next ... what you want to happen not some rule someone told you.

I tend to speak up about this since my first teacher filled my head with all these rules that took me years and years to break.

Yes, you also don't have to fire all clays to maturity if you happen to want to do something other than functional wares and like the lower fired color.

[Benhim]

Instructors have different reasons for the things they do in a student studio. My instructor could not fire as low as he liked in the student studio because they would break pots. He found that cone 08 was as low as he could go and have students do well. I have chosen to do cone 08 because it's what I'm used to working with and it works for me. I have not seen a reason to increase that temperature or decrease that temperature.

 

How would bisque firing pots to or very near maturity help you?

[Chris Campbell]

How would bisque firing pots to or very near maturity help you?

 

I'm assuming you mean the Cone 9 firing ... I use porcelain which needs to be supported during high firing or it will collapse, warp or slump. The only way I can glaze the whole piece is to fire it to maturity first then glaze at a lower temp where it does not need support. If I am going to glaze at high temp I can only do the unsupported areas. This works well for functional since the available area is usually the eating surface.

[Guest JBaymore]

Chris is "dead on".

 

See the discussion under "Bone China" eslewhere in the forum too.

 

Bisquing has a couple of goals.... but they are not always the SAME goals. The goals can vary to fit the needs of the finished wares. One can bisque lower than the finish firing... or one can bisque higher. In fact, one could bisque to the SAME temperature as the finish firing. A bisque is a first, non-finish firing..... that is all. Too many people automatically append the words "low temperature" to that term.

 

For centuries and centuries and centuries , it was not done at all. The advent of bisquing came pertty much in tandem with the industrial revolution...... to allow less skilled employees to easily glaze wares, and to allow certain types of decoration practices to be more easily acomplished. The practice extended out to studio artists from there. It works well with students, because of the same considerations that appiled to those "less killed workers".

 

Eventually it becomes the "but that is the way we've always done it" thing.

 

There are almost no things that are "absolute" in ceramics. Anytime someone tells you you that you MUST do this or that or that this ALWAYS happens......... take it totally with a grain of salt. Likely there are other ways to do whatever you are discussuiong, and there are conditions under which that does not apply or does not happen. For every "common rule" in ceramics, there are people breaking that rule daily, whethere studio artists or industrial ceramists.

 

Chris is SO correct about too many people conveying what really are personal experiences and personal breadth of understanding as absolute "rules" for ceramics. When working with students, it certainly helps to limit the information that is shared at any given point in time to focus on the needs at hand. But to not then later open up that understanding to a far broader picture of the reality..... is a serious disservice as an educator.

 

best,

 

.......................john

[Pres]

Chris is "dead on".

 

See the discussion under "Bone China" eslewhere in the forum too.

 

Bisquing has a couple of goals.... but they are not always the SAME goals. The goals can vary to fit the needs of the finished wares. One can bisque lower than the finish firing... or one can bisque higher. In fact, one could bisque to the SAME temperature as the finish firing. A bisque is a first, non-finish firing..... that is all. Too many people automatically append the words "low temperature" to that term.

 

For centuries and centuries and centuries , it was not done at all. The advent of bisquing came pertty much in tandem with the industrial revolution...... to allow less skilled employees to easily glaze wares, and to allow certain types of decoration practices to be more easily acomplished. The practice extended out to studio artists from there. It works well with students, because of the same considerations that appiled to those "less killed workers".

 

Eventually it becomes the "but that is the way we've always done it" thing.

 

There are almost no things that are "absolute" in ceramics. Anytime someone tells you you that you MUST do this or that or that this ALWAYS happens......... take it totally with a grain of salt. Likely there are other ways to do whatever you are discussuiong, and there are conditions under which that does not apply or does not happen. For every "common rule" in ceramics, there are people breaking that rule daily, whethere studio artists or industrial ceramists.

 

Chris is SO correct about too many people conveying what really are personal experiences and personal breadth of understanding as absolute "rules" for ceramics. When working with students, it certainly helps to limit the information that is shared at any given point in time to focus on the needs at hand. But to not then later open up that understanding to a far broader picture of the reality..... is a serious disservice as an educator.

 

best,

 

.......................john

 

 

When I was teaching I made certain to do the common kiln loading, unloading thing with the HS kids. My demonstrations always included a discussion of this is how we do it, and that some people don't do it, others do it at different temperatures, and in different types of kilns. It would usually bring on a discussion of why we do it this way. I would have a series of thrown mugs often that were fired do different bisque temperatures, and one greenware mug. In a class of 20 kids, pass them around and see how many would survive. Invariably all of them understood that the bisque fire mugs were easier to handle without breaking especially when some would want to pick it up by the handle, or the rim. Some lessons in life are easier learned in that way.

[Benhim]

I use commercially made porcelain which does get translucent, but I never make pots that will collapse. I've made some little porcelain cups that were translucent with shino on them, you could see light through the shino. These pots were just simple cylinders though that were self supporting.

 

I can imagine thin slip cast porcelain pots would fail in shallow forms like plates or shallow bowls. Is this a recipe you've made yourself or a commercial clay?

[Chris Campbell]

I use Southern Ice porcelain from Australia ... the problems in high firing come with most porcelains once you take the form past the self supporting stage. Also I work very thin which brings in other challenges. And I work with color ...

[Lucille Oka]

If you are new to ceramics and the clay supplier gives you a firing range for their clay use it until you feel it is time to deviate from it and you can.

You have to consider the "rules" as guidelines or suggestions so that you can have early success with the clay work.

Once you start to question the 'whys and wherefores' it maybe time to experiment with the different temperatures, techniques, clays, textures, and see what you get and see if you like it.

[Benhim]

I've heard good things about the southern ice, don't they make a cone 6 version now as well? It's a high silica clay body though if I'm not mistaken, which is why I've not gotten into it much. A lot of the clays we experimented with in college were high alumina porcelains. These had no problems standing up to high temperatures in pretty much any shape. Bowls do warp, but that was taken into account. We primarily experimented with a high alumina body covered in a multitude of flashing slips, fired in environmental kilns. Cone 10 reduction was our primary focus, although we also began to oxidize the flashing reds towards the end of the firing and slow cooling which promotes crystallization. It was a lot of fun, but nothing like the kind of porcelain you're doing.

[Marcia Selsor]

One reason to bisque to ^03 for majolica firings is it helps reduce crazing after the glaze firing. It bumps up the maturity of the earthenware as well.

I have seen this recommended by majolica artists like Linda Arbuckle and Rosie Wynkoop. Martha Grover recommended bisque firing porcelain to ^04 for a more hardy porcelain bisque to handle. Her pieces are very delicate. I bisque my terra sig pieces for potential saggar firing to ^09..so I don't lose the shine of the burnished surface. I bisque my paper clay slabs for raku to ^04. There are reasons for various temperatures.

 

Marcia

[Marcia Selsor]

I've heard good things about the southern ice, don't they make a cone 6 version now as well? It's a high silica clay body though if I'm not mistaken, which is why I've not gotten into it much. A lot of the clays we experimented with in college were high alumina porcelains. These had no problems standing up to high temperatures in pretty much any shape. Bowls do warp, but that was taken into account. We primarily experimented with a high alumina body covered in a multitude of flashing slips, fired in environmental kilns. Cone 10 reduction was our primary focus, although we also began to oxidize the flashing reds towards the end of the firing and slow cooling which promotes crystallization. It was a lot of fun, but nothing like the kind of porcelain you're doing.

 

 

Laguna Frost is manufactured in the US in Indiana. It is ^6 porcelain and will go translucent.

Marcia

[Benhim]

I fire my earthenware to cone 08 for bisque and then cone 1 for maturity in a glaze firing. I've been firing my cone 6 porcelain to cone 08 and then to cone 6 for maturity in a glaze firing. So one of the advantages of firing porcelain to maturity in bisque is to fire stuff on it's rim or prop it so that it does not sag. I can't seem to figure out how you're avoiding shivering when doing this type of work.