If the clay that you're using is newly purchased, and moist, then wedging clay when you are hand building is not essential. However, if the clay has an inconsistent texture or moisture level or contains air pockets, it's best to wedge it. If the clay isn't wedged it can be hard to handbuild even smooth forms.
Pug mills help to eliminate air bubbles, and make the clay a perfect consistency for throwing. Wedging your clay is necessary if it is recycled without a pug mill, or if the batch of commercial clay is older. You don't need to wedge your clay if it's a fresh box from the supplier, as the particles have not yet settled.
Wedging clay definition: the process of kneading the clay with the hands to remove air bubbles and ensure a homogenous mass. A fun exercise to see how long it takes to crate a truly homogenous mass of clay is to wedge together two chunks of different colored clays.
How do you prepare clay for handbuilding? Before starting to build your project out of clay, you need to knead it, a process also known as wedging. Kneading clay makes it easier to work and maintains a consistent moisture. It also eliminates air bubbles that may have been trapped when the clay was mixed or recycled.
It Makes the Clay Softer
Even if the clay isn't losing moisture, it can become stiff or hard if it sits around for a long time. Wedging helps the clay particles align with each other making the clay softer and easier to mold.
Often with ceramic clay, you will get harder patches in a bag of clay. This is why it is important to wedge it. The wedging evens out the clay and makes it a lot easier to throw. However, I found the air dry clay was quite homogenous straight out of the bag.
You don't want to wedge your clay too many times because you're using water with this technique. If you introduce too much water into the clay, it can soften the clay making it mushy and merely impossible to make anything.
If the clay that you're using is newly purchased, and moist, then wedging clay when you are hand building is not essential. However, if the clay has an inconsistent texture or moisture level or contains air pockets, it's best to wedge it. If the clay isn't wedged it can be hard to handbuild even smooth forms.
Professional clay artists love the canvas side for slab building, coil building and oh yeah, you can wedge on it.
Wedging- Spiral Method
Just like the Ramshead method, Spiral Wedging makes the clay more soft and workable as it removes air bubbles from the clay; combines variable clay consistencies; and aligns all the clay platelets in the same direction.
Stack-and-slam wire wedging is a method for wedging that is quick, effective, versatile, and easier on the hands and wrists than any other type of manual wedging. This method allows you to uniformly wedge very large pieces of clay for large pots.
Clay needs to be pliable and clean, with an even consistency. It needs to have the right water content, and not contain air bubbles. Wedging is an essential step in how to prepare your clay for pottery. It can help adjust the water content and consistency, and remove air pockets in clay.
It's better to wedge a little more on the wet side than dry. If it's too dry it will be too hard to work with. If you have some fresh clay use that as a guide, the consistency should be similar after wedging.
Clay straight from the ground does need to be processed. The clay will need to be sieved to remove unwanted material such as rocks, twigs, and roots. Sieving can be done either of two ways. The clay can be pulverized when dry and then sieved, or dried, slaked down in water, then sieved.
When clay dries, it shrinks and compresses, which in turn seals the solid wet clay in the center of the structure making it harder to dry out completely. That is why many potters poke holes through their Clay Sculptures. They may even take the clay out of the center of the sculpture.
Cement board is also a popular choice as a surface for rolling clay. Most cement boards are slightly absorbent. This means that provided your clay is not too wet and tacky, your slab will probably not stick as it's being rolled out. The other advantage of cement board is that it doesn't retain moisture either.
Concrete is a fantastic surface because it's cold, doesn't dry out your clay as much as plaster, and it's easy to clean after. You don't have to worry about wobbling or sliding edges with the floor. You can use all the force you need to Wedge and Hand build your clay, which costs nothing.
The clay drying process - Plastic is your friend!
It's a good idea to place a layer of rags or paper towels between the clay and its plastic cover to trap condensation. Replacing these wet linings with dry ones regularly permits gradual drying and prevents exposure to drafts that cause uneven drying.
Using clay that is too soft. Making your own clay and not mixing it well enough. Not wedging well enough. Making large pieces, especially flat ones having a big diameter.
Unfired clay is fragile. Unfired clay, if dropped, knocked, or bumped with another hard object, will chip or break easily. Clay that has not been fired if wet will lose its form. Clay that has not been fired has very little utility value.
Avoiding Air Pockets Altogether
When clay is mixed or recycled, air pockets get trapped in the clay. Wedging is the best way to eliminate them. Wedging is the most important step before playing with your clay. There are more benefits to wedging clay than just getting rid of air pockets.
THE MOST IMPORTANT THING TO REMEMBER IS, DO NOT OVER-FIRE!
(This is unlike glaze which must be fired to the exact specified temperature range.) If clay over-fires, it will first slump and bloat, and then will melt and potentially cause a lot of damage to your kiln.
Many potters have acquired carpal tunnel syndrome, a debilitating condition involving compression of the median nerve at the wrist. Tendonitis in various locations and tennis elbow are also common.
Above 1652°F (900°C), the clay body begins to shrink and vitrify. The silica starts to melt, filling the spaces between the clay particles and fusing them together (8-1 and 8-2). The fired clay is known as metakaolin. At 1832°F (1000°C) the clay crystals begin to break down and melt.