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Hello! 

New to the ceramic world and I am very interested in delving into Porcelain (cone 6) clay. I'm interested in designing  very contemporary and minimal jewelry, however I understand that porcelain shrinks significantly during the firing process. My question is: how would I go about firing Specifically rings? are there certain metal rods that I could use in the kiln, similar to a bead rack that can keep the ring smooth and even during the process and POSSIBLY true to the size once finished? I've seen many of these beautiful rings online and I'm very unsure how to fire them. Also, is it possible to use PMC shrinkage stoppers like they use in metal clay ring design? PLEASE help as I'm very stumped on approaching this.. it would be very much appreciated! 

 

lost,

Megan

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Because the shrinkage is the result of the evacuation of moisture from the clay on a molecular level, I don't believe you can do anything to mitigate the change other than calculating the shrinkage of your clay body and oversizing each piece as necessary. You can hang them from high-temperature wire, but if you fill the void in the center with no room to shrink, they will break.

As a jeweler who specializes in carving stones which are as hard or harder than porcelain, I do not suggest making rings from hard materials. Metals bend upon impact and even just from pressure - most thinner bands will actually go oval over time just from daily wear. Hard materials are also brittle and very susceptible to fracture from even small impacts because they are unable to absorb that energy. I have made rings in a variety of styles from quartz, agate/jasper, and jades and they've all broken eventually.

 

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Yeah imagine a porcelain ring breaking and cutting into your hand. Ouchie!  I cut myself over the weekend when I tossed some rejects against a tree, one didn't break so I bent over to pick it up and got myself in the finger.  

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Hi Megan:  welcome to the Forum.

you need to do some research on cone 6 porcelain. While it is true that many bodies run 13-16% shrinkage! there are also select ones that run 10.5 to 12. If you fire these bodies correctly: they will do just fine without the need for support. Warping and other distortions, generally do not occur unless you grossly over fire the recommended cone value.

i make my own bodies, so others will have to chime in availability. Most suppliers have charts that show shrinkage, some do not.

Tom

 

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1 hour ago, glazenerd said:

Hi Megan:  welcome to the Forum.

you need to do some research on cone 6 porcelain. While it is true that many bodies run 13-16% shrinkage! there are also select ones that run 10.5 to 12. If you fire these bodies correctly: they will do just fine without the need for support. Warping and other distortions, generally do not occur unless you grossly over fire the recommended cone value.

i make my own bodies, so others will have to chime in availability. Most suppliers have charts that show shrinkage, some do not.

Tom

 

Okay, thanks! That is very helpful! is there any additional advice you can offer for firing circular structures similar to these? 

 

3868ADAD-8127-4D3E-9C11-D5BEEF443054.jpeg

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What I would do is make a number of samples of different size rings larger than the final size desired after firing, measuring them bone dry and after the final glaze firing to see how much they actually shrink. Do this a few times to ascertain consistency. Keep a number of samples to refer to later.

JohnnyK

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7 minutes ago, JohnnyK said:

What I would do is make a number of samples of different size rings larger than the final size desired after firing, measuring them bone dry and after the final glaze firing to see how much they actually shrink. Do this a few times to ascertain consistency. Keep a number of samples to refer to later.

JohnnyK

Hi! Thanks!

I’m a little stumped because I’m confused as to how I should go about firing them.. I wonder if I need a structure to use to keep it perfectly circular while in the kiln. 

For instance, do I need to use rods, or some kind of structure, etc..

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For a cone 6 max firing I would use an alumina dowel or a silicon carbide dowel mounted horizontal for support.  Bisque fire to clay maturity; then apply very low fire glazes such as China paint.  Do not glaze the inside of the ring. 

Edited by Magnolia Mud Research

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Megan: the advice Johnny and LT gave is sound. After seeing the rings, I understand the attraction.

Those rings have been fired three times:

1. Bisq fire. 2. Glaze fire with zirco in clear glaze for the gloss white. 3. Gold luster applied, low fire to cone. 018?  Check the cone temp on gold luster.. Think that is right.

Tom

Edited by glazenerd
Cone rating changed to 018. TY Lady.

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Some general advice is to do a good amount of research before diving in with any ceramic project. The lusters you want to use are toxic to work with. If you use precautions it is not a problem, but if you don't it can lead to health problems. I don't know if luster glazes are safe after firing with prolonged skin contact. It's worth checking out before you make these.

Lusters are not glazes. They are metal and binders that melt and adhere to glaze and I am guessing they would not hold up to daily wear and tear on jewelry. If this is just for you and friends that may not be a big deal, but if you sell them you want to test the durability so you don't get angry customers. 

 

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On 3/26/2019 at 3:27 PM, douglas said:

Some general advice is to do a good amount of research before diving in with any ceramic project. The lusters you want to use are toxic to work with. If you use precautions it is not a problem, but if you don't it can lead to health problems. I don't know if luster glazes are safe after firing with prolonged skin contact. It's worth checking out before you make these.

Lusters are not glazes. They are metal and binders that melt and adhere to glaze and I am guessing they would not hold up to daily wear and tear on jewelry. If this is just for you and friends that may not be a big deal, but if you sell them you want to test the durability so you don't get angry customers. 

 

I think these are "occasional" rings, not daily-wear rings. Standard disclaimers regarding possibility of scratching of the gold and/or breaking the ring under high-pressure should be sufficient. 

@MeganH, you won't need to worry about distortion as long as you have not distorted the clay rings before they dry and if the rings aren't hanging during glaze firing from a narrow rod, but laying flat on an unglazed edge resting on a surface dusted with alumina (any residue washes off after firing). Unglazed area can be smoothed with emery cloth before the lustre ^018 firing.

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