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First bisque / glaze firing questions


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#1 NancyA

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Posted 25 January 2013 - 12:52 PM

Hello, I'm a newbie to both the ceramics world and to the forums and would truly appreciate the help of the wonderful folks here...
I'm interested in making tile. I've just purchased an electric Olympic doll/test kiln and will be attempting my first bisque firing within the next couple of days.

My only question about the bisque firing is how long should I prop the lid (I don't have a vent): until it reaches 800 degrees, when it is no longer steaming up a mirror, or some other way of knowing?

My questions in regards to the glaze firing:
1) Do I need to stilt the tile when using low fire commercial (06) glazes? The tiles will be small and unglazed on sides/bottom. I've read to use silica sand on the shelf beneath the tile. Is this necessary with a small 4" tile? I remember seeing a post here that using silica sand could be damaging to the elements/other wares.
2) As it is a very small kiln, should I enter a 'User Program' in the V6-F controller in order to allow for slower cooling of the glaze, or will the preset 'Slow' or 'Fast' settings be adequate? I realize that experimenting will probably be my only answer here, but I'd like the opinion of more experienced users on these controllers and what type of schedules they use in a test kiln to avoid glaze defects.

I apologize if these topics have been addressed, I have searched but was unable to come to a definitive answer on these. Many thanks to the fine experts here, I am so grateful for your responses on these forums. Don't know what I'd do without you!

#2 neilestrick

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Posted 25 January 2013 - 01:48 PM

Propping the lid won't be necessary if you leave the peep hole open. You should stilt the tiles if there's anything on the bottom of the tile. Even underglaze can stick a bit. But if the bottom is raw you don't need to stilt. With a small 4" tile at low fire you shouldn't need silica sand or anything like that iether. Slow cooling, hold times, etc aren't necessary. Use 'Fast Bisque' and 'Slow Glaze' and it'll work great. If you want to slow down the cooling, you could use a custom program, but try it without first and see if you like the results.

Neil Estrick
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Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com


#3 OffCenter

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Posted 25 January 2013 - 01:50 PM

Hello, I'm a newbie to both the ceramics world and to the forums and would truly appreciate the help of the wonderful folks here...
I'm interested in making tile. I've just purchased an electric Olympic doll/test kiln and will be attempting my first bisque firing within the next couple of days.

My only question about the bisque firing is how long should I prop the lid (I don't have a vent): until it reaches 800 degrees, when it is no longer steaming up a mirror, or some other way of knowing?

My questions in regards to the glaze firing:
1) Do I need to stilt the tile when using low fire commercial (06) glazes? The tiles will be small and unglazed on sides/bottom. I've read to use silica sand on the shelf beneath the tile. Is this necessary with a small 4" tile? I remember seeing a post here that using silica sand could be damaging to the elements/other wares.
2) As it is a very small kiln, should I enter a 'User Program' in the V6-F controller in order to allow for slower cooling of the glaze, or will the preset 'Slow' or 'Fast' settings be adequate? I realize that experimenting will probably be my only answer here, but I'd like the opinion of more experienced users on these controllers and what type of schedules they use in a test kiln to avoid glaze defects.

I apologize if these topics have been addressed, I have searched but was unable to come to a definitive answer on these. Many thanks to the fine experts here, I am so grateful for your responses on these forums. Don't know what I'd do without you!


This is what Olympia recommends:
If kiln has a vent, skip numbers 1& 4.
1. If the kiln has a lid wedge, prop the lid after loading the kiln.
2. Plug all observation holes except the top, which should remain unplugged throughout the
firing to allow a vent for fumes and vapors.
3. Key in the cone fire method you wish to fire.
4. After approximately 1 hour 45 minutes remove lid wedge and close the lid.
5. Allow kiln to fire until it shuts off.
A partially loaded kiln fires faster than a full one, so when firing partial loads, increase the length on LOW and MEDIUM to extend firing time.

I suggest leaving out the top plug and the lid propped only an inch or so until 250 degrees. The main danger of blowing up is at the boiling point (so just to be sure go 30 or 40 degrees past it) Close the lid at 250. Don't worry about venting for chemical water. Maybe when you get a little more confident with firings you will realize that you are just wasting electricity by venting at all.

1) Don't stilt and don't use sand. If the tiles were large (say over 15-inches) it might be helpful to use a little sand. Sand will not hurt the elements unless it gets on them. Obviously, putting sand on a shelf calls for great care not to let it fall on pots or any part of the kiln under the shelf (especially when unloading).

2) The firing schedule depends on the glaze and you're absolutely right in thinking that "that experimenting will probably be my only answer here". If your glazes are glossy then don't slow cool (Btw, if the program you're referring to is "Fast Glaze" or "Slow Glaze" that has no effect on the cooling speed after the firing cone has been reached.), if matt they may or may not benefit from a programed cooling.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#4 NancyA

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Posted 25 January 2013 - 02:02 PM

Thanks for the quick replies, your answers have given me the confidence to go forward now. I guess my husband was right when he said I was over-thinking things (I'm not going to tell him that, though) ;)

#5 Lucille Oka

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Posted 25 January 2013 - 11:41 PM

I recently purchased the very same test kiln. It is not a bad little machine. I have made 33 test fires so far. Overall it has not disappointed me. I have found that the programs I write as well as the cone fire programs are consistent from firing to firing.

For bisque firing I use my own written program based on information gleaned from several sources: The Orton Foundation, makers of the self supporting pyrometric cones that I use, Bartlett Instrument Company, the maker of the controller, Olympic Kilns, the maker of the kiln, Amaco, the manufacturer of the glazes I wanted to test, and the Skutt Manual, the best kiln manual I have ever seen.

The bisque cone fire programs have a pre-heat mode that is 3 hours long. I find this to be much too long for such a small kiln but there still needs to be a relatively slow heat rise. So I wrote my program to allow for this.

In bisque, I keep the wedge in from the beginning of the firing until the temperature reaches 1,000°F. The top peep remains open all through the bisque fire and cool down. I close the top peep only at the end of a glaze firing. The kiln cools down so quickly that I don’t wish to shock the glaze. The kiln can lose 600°F in 25 minutes.

Between 277°F and 896°F the fumes are strong. I don’t have a vent either but be sure to open all of the windows and doors and get a good fan that can move that air out it can be fierce. This goes for the bisque as well as the glaze fire; if you must, remove yourself to fresher air. You can set the alarm to sound so that you will know when to remove the wedge. I use Orton’s heat resistant gloves to do that.

This little kiln fires fast and cools down fast if you set it to do that. The offset feature takes a little bit of calculation to get it right; if you use it you’ll know what I mean.

One more tip the kiln is sensitive to static electricity so I never touch the panel with my fingers to program or to stop the alarm. I use an eraser at the end of a wooden pencil for all contact with the panel.

I hope this has been helpful. If you have any more questions do not hesitate to ask.




John 3:16
"For God so loved the world that He gave His only begotten Son, that whosoever believeth in Him should not perish but have everlasting life".

#6 Mart

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Posted 26 January 2013 - 10:48 AM

Nnormacluster, congratulations must be in order Posted Image
I am waiting for my own kiln too and waiting must be the hardest part. It will be here in a month or so.

BTW, I know this is completely off-topic and directed to Lucille only. Lucille, why are your post always with this huge font?
If you copy your stuff from word processing software like OpenOffice or LibreOffice etc, please remove the formatting. Posted Image
Thank you

#7 Mart

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Posted 26 January 2013 - 10:52 AM

The kiln cools down so quickly that I don’t wish to shock the glaze. The kiln can lose 600°F in 25 minutes.


Why are you not using slower cool down program? I still understand very lite of the whole process but isn't slower cooling good for most of the glazes?



#8 OffCenter

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Posted 26 January 2013 - 01:38 PM


The kiln cools down so quickly that I don’t wish to shock the glaze. The kiln can lose 600°F in 25 minutes.


Why are you not using slower cool down program? I still understand very lite of the whole process but isn't slower cooling good for most of the glazes?



Depends on the glaze. Some glazes look better with a fast cool down. Some look the same fast or slow. Some look better with a slow cool down. Matte glazes that need to form tiny crystals are noted for needing a slow cool down (but even those work better if some ramps of the cool down are fast and others slow and sometimes the extra heat work of firing those glazes one cone higher makes a controlled or slow cool down unnecessary). As with everything in pottery, it is all about observation and testing, not following rules.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.




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