Porcelain Information
I have bought 50 pounds of porcelain and started to make a ball-jointed doll.Wish me luck because i have no idea what I’m doing. I got Laguna clay. Its called Dave’s Porcelain (WC-384) and #570 are outstanding Cone 10 throwing bodies and are also excellent for slab projects when a hard clay is desired.
True porcelain contains a mixture of kaolin (pure white clay), silica, and feldspar. Porcelain is worked as a clay, but when fired it becomes similar to glass. Other unique qualities of porcelain
include translucency and whiteness. Porcelain is a clay body that draws in many a potter because of its bright white color, translucency, and the way glazes look oh so fabulous on it. But it’s a fussy little clay body susceptible to collapsing during the forming process and cracking during the firing. Plus it has a memory like an elephant – jiggle it the wrong way during the forming process and there’s a good chance it will remember your mistake during the firing resulting in a warped pot.
Porcelain (called “jiki” in Japanese) was introduced to Japan in the 17th century by Korean potters, and was influenced greatly by Chinese Ming Dynasty (1368 – 1644) orcelain, an ingenious pottery product first developed during the Shang Dynasty in 1600 BCE, represents both beauty and grace in Chinese pottery. Because of its unique material properties, porcelain has considerable strength, hardness, whiteness, translucence and insulation. By 600 AD, porcelain-making techniques had been perfected, and Chinese porcelain began spreading outside China. These exported Chinese porcelains were held in such great esteem in Europe that in the English language china became a commonly–used synonym for the Franco-Italian term porcelain.
In 1749, Thomas Frye took out a patent on a porcelain containing bone ash. This was the first bone china,
Some porcelain bodies tend to be deflocculated, which causes the body to have working and drying problems. Deflocculated clay are thixotropic, and become softer when moved. This means a piece that feels dry enough to trim may become much softer as it is worked upon. Deflocculated bodies have trouble drying, as the parallel clay particles at the edges pack together as the water evaporates, closing the path for interior water to exit. This can cause uneven shrinkage that results in warping and cracking.
The density of the clay may cause edges and extensions to dry before the rest of the work, with the potential for cracking. Careful drying can address this.
In firing, true porcelain is fluxed enough to vitrify and become translucent when thin. This may cause warping and cracking in firing. Commercial producers may address this difficulty by bisquing porcelain bodies to maturity in supports or bedded in alumina oxide, then using special glaze gums and binders to apply the glaze to the vitrified wares, and firing lower for the glaze firing.
Clays used for porcelain are generally of lower plasticity and are shorter than many other pottery clays. They wet very quickly, meaning that small changes in the content of water can produce large changes in workability. Thus, the range of water content within which these clays can be worked is very narrow and the loss or gain of water during storage and throwing or forming must be carefully controlled to keep the clay from becoming too wet or too dry to manipulate.
Unlike their lower-fired counterparts, porcelain wares do not need glazing to render them impermeable to liquids and for the most part are glazed for decorative purposes and to make them resistant to dirt and staining.
Decoration: Porcelain wares may be decorated under the glaze using pigments that include cobalt and copper or over the glaze using coloured enamels. Like many earlier wares, modern porcelains are often bisque-fired at around 1,000 degrees Celsius, coated with glaze and then sent for a second glaze-firing at a temperature of about 1,300 degrees Celsius or greater. Another early method is once-fired where the glaze is applied to the unfired body and the two fired together in a single operation.
Armatures for sculptures Information
If you’ve been following my adventures in sculpting, you would know I’ve been struggling with what to use in internal support of my figures. I’ve used wire, which seemed to work. I’ve used wood which may or may not have caused cracks. Maybe the cracks would have appeared anyway? So as is my usual way of doing things; I am doing more research now , after I’ve experimented.
Armatures:
- Stainless steel- will withstand 2150 degrees F , cone 5. It can stay in the piece but must be wrapped with paper so the clay can shrink against it. The paper burns away and gives shrinkage room.
- Nylon mesh or nylon wire- gives support during construction but burns out during firing.
- Wood- must be wrapped and removed before clay dries
- Pipes- must be wrapped and removed before clay dries
- Glass Bottles- must be wrapped and removed before clay dries
Source:Working with clay
By Susan Peterson, Jan Peterson
Sculpting Eyes
I thought I had a good way to make eyes for my little sculptures, until yesterday.
- I would hallow the head out once it was hard enough to do so without collapsing.
- Then I would smoosh in eye bals from the back into the eye holes.
- I would lay down skinny, tiny srips of clay above and below the eyes to make the lids
- Let it stiffen up a bit and then carve in the iris and pupil.
- WaLa! A nice eye.
From Drawing the Head and Hands by Andrew Loomis
Watch this guy do it. I bought his book. He is REALLY good. But he works much bigger than I do. Maybe I should work bigger? It sure would be easier.
Here’s some other eyes instructions by Gene Van Horne
:
Sculpting eyes is actually quite easy…
1. Create an eye socket using a ball burnisher type tool. Not too deep, not too shallow, just a nice little dent.
2. Where you want the corners of your eyes use a pin and poke in each corner straight in to the head. This causes the putty in the socket to bulge up some and creates your eyeball.
3. Use a sharp small tool, I use a .032 piece of brass wire that has been pounded out and sharpened and buffed smooth. See http://www.perfect-t…m/newpage11.htm and click on the SUPERFINE PRO METAL TIP TOOLS picutre. Look at SFP-4J Straight Spatula (fourth tool down from the top) and that’s basically what I use for creating the eyelids. Take the very tip of the tool and very carefully make four marks, each starting from the holes you just poked, angling up for the upper lid and angling down for the lower lid. Pull out a tiny bit of putty from each mark you make to create your eyelids. Like this… <> I usually start on the inside upper corner and work around clockwise. Don’t push in hard or you’ll sink in the eyeball. It’s all about pulling OUT the eyelids. Look at one of Werner Klocke’s figures and you’ll see what I’m talking about.
4. Finish off by pressing up and in lightly with either a clay shaper or a spoon type tool, a little above the eye to create the browline. If you want an eyebrow push in and down very lightly with the same tool, a hair above the browline to define the brow. You don’t need to deliniate hairs on the eyebrows unless they are bushy. If they are really bushy you’ll have to add putty and then texture them.
Eyes almost never stare straight ahead, but commonly look a bit to left or right. I find the informality of a slight sideways glance simplifies the overall problem and makes the eyes more attractive.
A video of making eyes by Joanna Mozdzen http://www.joannamozdzen.com
Nakkid Sculptures
I must admit , I really hate covering up those beautiful naked bodies. I first sculpt all my people naked. Yes, its true , I just love the human body. I think it is very beautiful. But the other reason is because it helps with the form, winkles and folds of the clothing put on top of it. The clothes look best when the shape of the body show through. Just look at what you are wearing now(assuming you are wearing any) and notice how the clothing is shaped by your body underneath.
This little Gnome is sleeping, so he is only wearing his pointed boots and hat. He doesn’t like to feel restricted when he’s asleep.
Water Based Clay drying Tips – No cracks or explosions!
Cracking in water based clay can be caused by any one of a number of issues, but usually involves one or more of these conditions:
* If there is a rigid armature inside that doesn’t collapse while the piece is drying, then the clay will crack around the armature. Solution is to not have an armature inside, or use crumpled newspaper that will “give”
* If the piece dries too fast or is left to dry in the open air it will crack. The outer layers dry faster than the inner layers and as clay shrinks as it dries, the outer layers will crack. Solution is to dry the piece slowly, covered in plastic.
* If the clay is unsupported in certain areas, the weight will cause the piece to crack under the stress. Solution is to prop any portion up that tends to sag with pieces of wood or other solid structure until that portion has dried or is very firm and will support itself.
* If the piece is not totally bone dry when it is fired, the escaping steam will crack the clay. Solution is to make sure the clay is dry. Put it in a roasting turkey bag in the oven and turn it on about 180 degrees overnight, then turn off the oven. If you see steam on the inside of the bag, the piece is not dry enough to fire. A piece that merely cracks or breaks can be easily repaired. A piece that explodes into dust cannot. Poke a dozen holes in the bagand then bake in your oven to 180 degrees all day long. Turn it off at night time and leave it sit. Keep doing this until the morning you check it, it doesn’t have any water vapor on the inside of the bag. Then is when it’s completely dry.
* If you put too dry clay on top of leather dry clay while modeling, the new clay will not adhere to the existing clay and will tend to separate and crack. Solution is to always keep the piece you are working on nice and moist and to only add really wet clay while modeling so it will “glue” itself to the existing clay and form a bond.
* If you build a piece thick and when quickly building up the initial layers get air trapped inside the clay, the piece will burst when firing. Solution is to form your initial mass, then while the clay is still quite soft, paddle the clay to smash out all the air bubbles, then build more layers with wet clay. Also, if firing thick, the clay needs to be a clay that contains grog and the firing must commence slowly over a period of at least a day. If the temp is brought up too fast, the clay can burst. Otherwise, the piece must be cut and hollowed out to about 1/2 inch even thickness and holes pierced on the inside of the clay as is instructed in a typical ceramic clay class. When putting the halves back together, the clay must be super wet and the exposed edges scored, or the clay will crack along the seam due to improper adhesion issues mentioned in the previous bullet.
* EM217 is a modeling clay only and really should never be left to dry past leather hard since it should not be fired. It is a very fine clay with no grog and will almost certainly crack if it is left to dry out. It can be molded while still wet.
everyday art by Kathy O'Connell 