Establish depth and width: If you’ll use your wedging table to dry out clay that is being recycled, or if you’re planning on wedging large amounts of clay at one time, you will want a larger surface area than if you will only be wedging up a few pounds at a time.Establish height: Each table should be configured to suit the height of its owner. If it will be used by a number of people, calculate an average height to find a compromise. As a rule of thumb, a wedging table’s height should be set at approximately the same height as the points of your hip bones. Proper height will decrease the discomfort of bending over a too-low table, or the inefficient use of your muscles if set too high.
In the diagram, the featured wedging table is 32 inches high by 28 inches deep by 28 inches wide. It calls for 2 x 4 lumber for the legs and sides, 5/8 inch (minimum thickness, you can go thicker) plywood for the floor, and leg braces made from 1 x 3 lumber.
Materials You’ll Need
Six 2 x 4 x 32 inches lumberTwo 2 x 4 x 28 inches lumberTwo 1 x 3 x 32 inches lumberOne 1 x 3 x 64 inches lumberOne 32 x 32 x 5/8 inch plywood (which will translate to a 28 x 28-inch interior) that has no cracks or warping
Other Supplies
One 1 lb. box 3" x 7.62 cm exterior wood screws One 1 lb. box 2-1/2" x 6.35 cm exterior wood screws Wood glue Container of silicone caulking Lots of dry plaster of Paris (see step five to calculate how much you will need)
Begin Building Your Wedging Table
To begin the frame, first, gather your supplies and tools together. Recommended tools include:
Work table or woodworking bench Drill with bits and Phillips head screwdriver attachment Jig saw with ripping or all-purpose blade Circular saw Tape measure Pencil or marker Hammer (optional) At least two clean plastic buckets and a scale, which you will need later for the plaster.
This project will go much easier if you can recruit another person to be your helper. If you can’t find a building partner, use a good woodworking bench that can clamp onto the lumber as you work with it. At this point, you should have the legs and walls attached to each other. The table begins to take shape.
Cut the Floor of the Wedging Table
In order for the floor of the wedging table to support the weight of the plaster, you’ll need it to extend to the outer edges of the walls. Measure then cut the plywood to the interior width and depth dimensions of your wedging table plus an extra 4 inches per dimension. (For example, if the interior is 28 x 28 inches, cut a square of plywood that was 32 x 32 inches.) If you have excess plywood, you can either cut off the excess at one side, or you can notch the plywood for the legs, as featured in this photo. Notching the plywood allows the plywood to overlap the edges of the walls slightly, which in turn means that the screws will not be near the edge of the plywood once they are set. This decreases the likelihood of the plywood cracking between the screw and the edge of the flooring sheet. Before going further, set the floor in place, without any glue or screws. A dry run ensures that the floor will fit perfectly, without taking the chance of misaligned screw holes or the mess of glue in the wrong places.
Complete the Wedging Table Frame
Once the floor piece has proven ready, set the floor in place:
Finish Your Wedging Table
You need to allow time for the wood glue to cure. Generally, most wood glues are completely cured within 24 hours, but some can need 48 hours before you should continue with the next step. Check the label of your glue for information on that particular glue’s guidelines. Once the wood glue has cured completely, you need to caulk all the interior joints in the box of the table where the plaster will be poured. Press the caulk into the joint areas so that it pushes deeply into all cracks. Once applied, the caulking will need to cure. Check the label for the specific curing time for the glue you selected. If possible, set the wedging table where you want it before mixing and pouring the plaster. If your wedging table will be in an area where clay is being worked or in an area you don’t want forever messed up, mix and pour the plaster into the table outside.
Plaster Tips
Plaster and plaster dust must not be allowed to get into any working clay. It will literally explode in the kiln during firing. Have a minimum of two clean buckets. One to mix the plaster in, and one for you to rinse your hands in. Line the rinse bucket with a trash bag prior to filling with water. Only use fresh plaster. Do not use old plaster, as it will have lumps in it which makes it unusable. Only use drinkable tap water or distilled water to avoid adverse chemical reactions. Water must be about 70 F/21 C for optimum setting time. Weigh out everything and make all calculations before beginning the mixing. More on that below. Sift plaster into the water slowly. Do not dump plaster in. Allow the plaster to soak for one to two minutes before you begin stirring it. Use your hand to stir it gently (don’t create air bubbles) and break up any lumps. Rinse your hands in the lined bucket. Do not dump this water into any plumbing fixtures. Once the plaster has settled for at least one day, pour off the water and discard the remains in the trash. Pour the plaster into the wedging table slowly and carefully. Tap the table to release any air bubbles. To remove the pour marks, smooth out the surface using a length of wood or another straight edge. Dry the plaster slowly and as evenly as possible. For such a large volume, drying time can be two weeks or more.
More on Water to Plaster Ratios
Estimate your wedging table’s volume in cubic inches. Example calculation: 28 inches x 28 inches x 4 inches = 3136 inches cubed.Divide by 231 to find gallons or 58 to give quarts. 3136 / 231 = 13.6 gallons.Subtract 20 percent, since that much volume will be taken up by the plaster.13.6 x .8 = 10.9 gallons.
The result is the amount of water you’ll need. Each gallon of water requires 11 lbs 6 oz (5,171 grams) of plaster.
