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What Is The Most Incorrect "rule" You Ever Heard For Pottery?

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#21 TJR

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Posted 16 July 2013 - 08:26 AM

 

I think Mark and Jim should meet in a neutral point-say Canada. Mark can try cone 6 clay to see if it is stong enough. Jim can use a splash pan. Later, they can drink some stong Canadian beer, and laugh about their differences. Leave your guns at the border.

TJR.

I support this idea.  Though, to be fair, isn't saying "Strong" Canadian beer a bit redudant?

 

Made me laugh! Clever and witty at the same time.

T.



#22 OffCenter

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Posted 16 July 2013 - 08:38 AM

The most contentious one discussed on this forum is splash pans which are reported to not be needed. As the car guys say BOOGUSSSSSSS- Each to thier own I say-some like them so do not.  Just another tool to be used or not.

People do use them to collect great slip for additives to clay or slip and also for keeping an area clean.

 

You're confused again, Mark. There has never been a RULE that you can't use a splash pan. I'm flattered that you think I can make rules, but I can't. I just make fun of splash pans because for me personally they are unnecessary, in the way, something else to clean, and add to the cost of a wheel. I do have to admit that I do use them when my roof is leaking. Splash pans, Griffin Grips, and the Quick Centering Tool are just tools that anyone is free to use or ridicule.

 

Jim


E pur si muove.

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

#23 Claypple

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Posted 16 July 2013 - 09:54 AM

The most prevalent one is that ... clay fired to higher cones is stronger than clay fired to lower cones.

 

Jim

 

Does the higher cone do a better vitrification? Any other benefits of the higher cone at all?



#24 timbo_heff

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Posted 16 July 2013 - 10:23 AM

The most egregiously wrong thing I've seen: "expert" wood fire team telling students to BISQUE THE CONE PACKS before loading .

 

WOW !!!



#25 Chris Campbell

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Posted 16 July 2013 - 10:31 AM

The most egregiously wrong thing I've seen: "expert" wood fire team telling students to BISQUE THE CONE PACKS before loading .

 

WOW !!!

 

You win for now timbo_heff ... that is one I have never heard before ... I cannot stop laughing.


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#26 OffCenter

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Posted 16 July 2013 - 11:12 AM

 

The most prevalent one is that ... clay fired to higher cones is stronger than clay fired to lower cones.

 

Jim

 

Does the higher cone do a better vitrification? Any other benefits of the higher cone at all?

 

 

Absolutely not and no. Firing to the maturity point of the clay and the composition of the clay determine the strength of clay. I really don't want to get into it again because it has been debated here to exhaustion, but Pete Pinnell published the results of the testing he and his university ceramics classes did a few years ago. The test used to determine the fired strength of clay is called a MOR (Modulus of Rupture) test. After a lot of testing the results were what they were expecting in that some mid-range clays were stronger than some higher fired clays and vice versa. What surprised them was that one of the earthenware clays fired to cone 03 or 04 or something like that was the strongest clay tested. Pinnell's tests weren't the only MOR test to prove that but was the most recent. You don't have to do MOR test to see the obvious; you just have to use a lot of different clays. For example, there is no doubt in my mind that my cone 6 porcelain is stronger than my cone 13 woodfire clay and just as strong as my cone 10 porcelain.

 

Jim


E pur si muove.

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

#27 Benzine

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Posted 16 July 2013 - 11:53 AM

"The test used to determine the fired strength of clay is called a MOR (Modulus of Rupture) test."

 

It's also the name of my upcoming concept album.


"Anything worth believing, is worth questioning"

#28 OffCenter

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Posted 16 July 2013 - 12:02 PM

"The test used to determine the fired strength of clay is called a MOR (Modulus of Rupture) test."

 

It's also the name of my upcoming concept album.

 

Figures! Are you still using a sofa to sit on when you throw?


E pur si muove.

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

#29 Benzine

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Posted 16 July 2013 - 12:31 PM

 

"The test used to determine the fired strength of clay is called a MOR (Modulus of Rupture) test."

 

It's also the name of my upcoming concept album.

 

Figures! Are you still using a sofa to sit on when you throw?

 

Naw, I've moved on to a padded desk chair.....I'm serious.


"Anything worth believing, is worth questioning"

#30 mregecko

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Posted 16 July 2013 - 12:50 PM

1. Never trim the inside of a bowl. I don't do this often but recently tried it after watching the video of the potter trimming the large, porcelain bowl. It works.

2. Never throw down. If a cylinder gets off-kilter or torqued, throwing down toward the wheel will often correct the problem.

 

#2 is my favorite! I just found this out a few months ago, when I was throwing some thin spouts for ring holders. Throwing down helped even out when I had weird torsion!



#31 oldlady

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Posted 16 July 2013 - 01:00 PM

you cannot EVER put greenware and bisque in the same glaze firing.


"putting you down does not raise me up."

#32 trina

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Posted 16 July 2013 - 02:13 PM

It has been proven so please stop saying it can't be done, Sea monkeys CAN live in the washup barrel!

T



#33 ayjay

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Posted 16 July 2013 - 02:25 PM


My first pottery teacher was just a treasure trove of false information and iron clad rules that were her opinion only and nowhere close to the truth. She proudly claimed to be totally self taught ... or not.

 

I'm not very good at listening to rules, so can't claim to remember any bunkum ones - but...........

 

I often work with another carpenter who claims to be self-taught.................... I  usually retort that I don't think he was paying enough attention.



#34 Mark C.

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Posted 16 July 2013 - 02:29 PM

I knew that splash pans would draw a response

Hey for some reason my pit fired dinnerware is not holding up ?? Any ideas why?I know its vitrified

 

 

Real Myths I have heard

Pots need to breath  leave  lots of space between them (when loading into a kiln)

Cones go bad (only when they get wet)

Pottery cannot be thrown and fired same day-(drop by some sunny day and see how this is done)

Mark


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#35 OffCenter

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Posted 16 July 2013 - 03:28 PM

I knew that splash pans would draw a response

Hey for some reason my pit fired dinnerware is not holding up ?? Any ideas why?I know its vitrified

 

 

Real Myths I have heard

Pots need to breath (when loading into a kiln)

Cones go bad (only when they get wet)

Pottery cannot be thrown and fired same day-(drop by some sunny day and see how this is done)

Mark

 

The reason your pit fired dinnerware is not holding up is because it is not vitrified (and because it doesn't exist). Drop by on a cloudy day and see how I can throw a pot and fire it the same day. (Pretend I inserted a smilely face here.)

 

Jim


E pur si muove.

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

#36 Claypple

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Posted 16 July 2013 - 07:32 PM

 

 

The most prevalent one is that ... clay fired to higher cones is stronger than clay fired to lower cones.

 

Jim

 

Does the higher cone do a better vitrification? Any other benefits of the higher cone at all?

 

 

Absolutely not and no. Firing to the maturity point of the clay and the composition of the clay determine the strength of clay. I really don't want to get into it again because it has been debated here to exhaustion, but Pete Pinnell published the results of the testing he and his university ceramics classes did a few years ago. The test used to determine the fired strength of clay is called a MOR (Modulus of Rupture) test. After a lot of testing the results were what they were expecting in that some mid-range clays were stronger than some higher fired clays and vice versa. What surprised them was that one of the earthenware clays fired to cone 03 or 04 or something like that was the strongest clay tested. Pinnell's tests weren't the only MOR test to prove that but was the most recent. You don't have to do MOR test to see the obvious; you just have to use a lot of different clays. For example, there is no doubt in my mind that my cone 6 porcelain is stronger than my cone 13 woodfire clay and just as strong as my cone 10 porcelain.

 

Jim

 

Thanx Jim! I thought at first that you were saying that you do not have to fire clay up to the maturity temperature.



#37 Pugaboo

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Posted 16 July 2013 - 09:50 PM

Okay so the rule about air bubbles isn't true? I live in terror of air bubbles exploding my ware! In fact I was at the group studio the other day and someone else's piece was laying on the kiln room table in what was shards basically. I asked what happened, thinking maybe the clay had not been dry enough to bisque since it was quite a thick piece. I was told that no most likely they had used reclaimed clay and not properly wedged it so it had air bubbles and that's why it exploded.

So ARE air bubbles a major issue? Or am I wasting my time wedging my clay until my arms are numb? I should also state in full honestly that I am also terrified of firing possibly damp pieces so often keep them for weeks before firing just to be sure they are dry. The "it will feel cool if damp test" doesn't work when it's been raining for so long I am considering purchasing an ark.

Can you tell by looking at an exploded piece what caused it?

Love this topic by the way I am learning a lot.

Terry
The world is but a canvas to the imagination - Henry David Thoreau

#38 oldlady

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Posted 16 July 2013 - 10:33 PM

no, air doesn't do it.  water does.  water expands as it heats.  if you are in doubt about the dryness of a piece, just put it in your kiln and set the controls to preheat.  you can choose the length of time to preheat but my kiln rep says that the speed of getting it up to boiling, 212 degrees is so slow that the hold time of 15 minutes is enough.  i assume you are not trying to fire a brick thick item or a bowling ball.

 

if you really worry about that piece that exploded, look at closely and see if you can see how thick it was.  new throwers make very thick bottoms without realizing it.  when you start throwing, cut the pots in half downward and check the thickness.  remember that when you are starting out you are learning a skill, not making a product.  cut down ten or so and get familiar with the feeling of the thickness.  don't get hung up on making something until you can do it well.


"putting you down does not raise me up."

#39 Min

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Posted 16 July 2013 - 10:58 PM

Okay so the rule about air bubbles isn't true? I live in terror of air bubbles exploding my ware! In fact I was at the group studio the other day and someone else's piece was laying on the kiln room table in what was shards basically. I asked what happened, thinking maybe the clay had not been dry enough to bisque since it was quite a thick piece. I was told that no most likely they had used reclaimed clay and not properly wedged it so it had air bubbles and that's why it exploded.

So ARE air bubbles a major issue? Or am I wasting my time wedging my clay until my arms are numb? I should also state in full honestly that I am also terrified of firing possibly damp pieces so often keep them for weeks before firing just to be sure they are dry. The "it will feel cool if damp test" doesn't work when it's been raining for so long I am considering purchasing an ark.

Can you tell by looking at an exploded piece what caused it?

Love this topic by the way I am learning a lot.

Terry

 

Air bubbles don't cause pots to explode but they do have a nasty habit of showing up in the finished ware. Pots with rolled rims have a lot of air trapped but don't explode (if dry when fired).

 

If you put a greenware piece against your cheek it should not feel cold, but cool is okay if the pots are drying in a cool room. If in doubt candle the pieces overnight with the lid propped open a couple inches. I know it's unorthodox but I have also dried pots in the kitchen oven, 175F with the door propped slightly open with a knife blade.  

 

What kind of wedging do you do to make your arms numb? Do you have your wedging table at the correct height? I'm 5' nothing and use a horizontal filing cabinet to wedge on that's about hip height. 



#40 Claypple

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Posted 16 July 2013 - 11:05 PM

 

 

 

Figures! Are you still using a sofa to sit on when you throw?

 

Naw, I've moved on to a padded desk chair.....I'm serious.

 

 

What is next? A rolling chair?  :)






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