C LA Y / G L A Z E S / F I R I N G
SUPPLY PICK UP
Please email your Clay Lead Sa Liu to co-ordinate a pick up time for your clay block a couple of days ahead of your class.
MATERIAL LOCATIONS
- Accessories – cutting tools, carving tools, texture tools, rolling pins, templates, cookie cutters, cupcake molds, paper bags and cardboard for placemats, etc. are in the pink cabinet in the outdoor Kindergarten Courtyard.
- The slab roller machine is in portable 159 inside the unlocked cabinet.
- Glazes and Brushes are in the Explore Art supply room.
- Water cups are in the Explore Art main supply room.
- The Kiln is located in the Kindergarten Pod next to the bathrooms. This door is always locked. Our Office Manager, Mr. Patrick Heaviside has the key to the kiln room in the front office. Please sign the key out and return it immediately after you are done.
KILN CALENDAR
- The Ceramics/Kiln Calendar is on the desk of the office manager. You must sign up to use the kiln. If you miss your scheduled load time you must re-schedule yourself. Maintaining the calendar is courteous and necessary.
- Please plan to load the kiln between 9:00 – 10:00 am on your scheduled day and unload the following morning BEFORE 9:00 am. This is important because the kiln cannot be running during non-school hours after 3:00 pm.
INSTRUCTIONS FOR WORKING WITH CLAY
One 25 lb. bag of clay is allocated to each class of 25 students or less. For larger classes, 1½ bags of clay are allotted. If you need more, please let us know so we can plan accordingly. Please tightly seal any unused clay in a ziplock bag and leave it in the clay cabinet.
Have the children create nothing less than ¼ inch thick and nothing more than ¾ — 1 inch. Pieces that are too thin become extremely fragile when bone dry and can break. With pieces that are too thick, it is difficult to determine if the center is completely dry, and they are more likely to contain bubbles that will explode during firing.
Slip is a clay and water mixture used for joining pieces of clay. First the clay must be “scored.” Hatch marks ///// vertically and horizontally to create tic-tac-toe marks ### must be made with the clay tools on both clay pieces being joined together. Add water with a fingertip into the scoring marks to create the slip (glue) to join the pieces together. Clay and sediment do not go down the sink. When cleaning up, slip must be tossed in the trashcan.
When possible, have the students impress their initials on the bottom of the piece (careful to check for duplicate initials in the classroom). A “fire proof” pencil can be used to put the names on their projects. It is located in the kiln room.
If the clay project contains a hole to string twine through later for hanging, be sure the hole is completely cleared of clay before it dries.
Art work MUST air dry AT LEAST 14 days prior to initial bisque (unglazed) firing. Plan to dry these in the classroom, pod, on top of cabinets in the corridors, or on the white shelves in the Explore Art workroom – NOT in the kiln room. To eliminate accelerated shrinkage/warping, slow down drying time by covering projects with plastic wrap for the first several days.
Pieces are fired twice:
1) Bisque firing (unglazed): takes the item from a dry and fragile state to a
hard and strong one.
2) Glaze Firing: will make the item colorful, shiny and watertight.
BISQUE FIRING (First Firing)
Bone dry (at least 14 days!) greenware (unfired clay) are loaded directly onto the bottom of the kiln. Position the risers for the shelves before you begin to load your items and then place ceramic art projects around them. Add shelves, position the next set of risers and continue to load in that manner. Staggering the heights of the shelves will allow for better airflow around the pieces. Greenware can be carefully stacked or nested if space is an issue.
Shelves are treated and protected with kiln wash. It is very important that all items placed on the shelves are on the treated side. Be sure to take note of the “Clay Up” the direction of the arrow on the side of each shelf.
If the student’s initials are not carved on their pieces but are on a labeled plate or paper, you may need to make a “kiln map” as you load to keep track. Upon unloading, use the map guide to just replace the piece to its labeled plate.
The kiln is pre-programmed. There is a switch on the kiln room wall that will turn on the exhaust fan and power up the kiln. You will find step-by-step instructions for running the kiln on the wall. It is the same procedure for both bisque and glaze firings.
GLAZE FIRING (Second Firing)
Glazes are EXPENSIVE! Use them, but do so conscientiously. They are in squirt bottles so the ADULTS can easily distribute them into Dixie cups. Start with less and add more as needed. Glaze is applied with paint brushes. Unused, uncontaminated colors can be returned to the bottles by simply squeezing the glaze out of the cups.
The color of the unfired glazes (in the bottles) is different than the final fired color. There are fired glaze squares in the Explore Art supply room below the glazes to use as reference for how each glaze will look after its fired.
Use thin layers of glaze. Three layers will produce the best, most vibrant color.
Students should avoid getting glaze on the bottoms of the pieces. Should glaze drip or puddle onto the bottom, it can be easily cleaned off after the glazed piece is dry by rubbing a damp sponge on the bottom surface. Always check the bottoms of the pieces to be sure they are clear of glaze. If there is any doubt, put the piece on a stilt to raise it off the shelf. Glazed pieces CANNOT touch each other, the shelves, the walls of the kiln, or any part of the stilt except the metal spikes. The metal nails in the stilts will not fuse to the piece.
Make sure that if the project contains a hole for hanging later, the holes are completely free of glaze before they are fired, or you will wind up with a clay project that no longer has a hole.
REPAIRS
Broken pieces of art: An unglazed broken piece can often be “glued” during glazing by using the glaze as glue. This only works when gravity is on your side – if the broken piece can remain in the desired location before it is “glued” it will fuse. If the broken piece remains in the desired location as a result of the glue, it will slide in the kiln. Do not take the risk if there is a possibility it will slide off onto the shelf!
Broken pieces after firing can usually be repaired with hot glue or E6000.
EXPLORING CLAY PROPERTIES AND TECNHIQUES
Every experience with clay is a valuable learning opportunity. Children will naturally gain the skills to work and manipulate clay better with every interaction. Because their hands are the tools, they become more involved and connected in the creative process and tend to be more forgiving of their own skill limitations than they might be with other media. The clay process seems to produce less frustration and yields a clear sense of satisfaction and accomplishment.
When students are introduced to clay and hand-building techniques in a logical and sequential order, they will build on their knowledge and skills. Children need to have the opportunity to play with the clay to become familiar with its properties as they are learning to incorporate new techniques. With a thoughtful curriculum and appropriate projects, a balance of play and technique can be easily attained to produce structurally sound pieces that they can be proud of.
As students gain experience with one technique, it can be combined with another for a whole new project. Also, adding texture creates opportunities for new and interesting ideas.
PRIMARY METHODS
Pinch Method: Primarily used for bowls and small sculptures. Basic pinch pots begin with a smooth ball of clay. Squeezing and pressing your thumb into the center of the ball with one hand, supporting it in the palm of your other hand, rotate the ball and work the walls of the bowl outward, gently pressing/squeezing small amounts while rotating.
Coil Method: This is one of the oldest ways of forming pottery. The coil method allows you to make larger vessels than with the pinch method. Vessels or bowls can be formed by wrapping a rope of clay around a base, stacking and joining the coils to the shape and height desired. Students will create coils in the diameter that is most comfortable for them. Discourage coils that are as thin or thinner than a pencil. Be certain to join the coils by scoring.
Slab Work: Slab work is created with a rolling pin and can be used for shallow bowls, tiles, and dimensional images. Students should pat out the clay into a flat shape before beginning to roll. Rolling gently from the center, outward, the slab is thinned a little at a time. After each round of thinning the slab, lift the clay and flip it to the reverse side. This makes rolling the slab easier, maintains an even thickness, and keeps it from sticking and distorting when removing it from the placemat.
JOINING CLAY
Clay pieces will adhere to each other better if they are moist and also have the same moisture content. Because some projects need stiffer clay for structural stability, you need to familiarize yourself with which moisture level works best for the project you are working on.
Slip: A mixture of clay and water used to attach pieces of clay together. Slip can be used to repair artwork that has broken before the first (bisque) firing.
Score: Use a tool to scratch/hatch the surfaces that are being joined. Add water to the scored surface, slide and wiggle them together until slip is developed and the pieces take hold well and do not separate when tugged.
Lute: Most often used to join coils together, and used in conjunction with scoring. Using a finger, squish and smooth the clay from each of the joined pieces together at the contact point.
STATES OF CLAY
Moist clay: This is the easiest for children to work with and manipulate. Most projects will require clay right from the bag and should be soft and moist. Larger projects may need harder clay at the base to support weight (i.e. a tall coiled vessel); however for classroom purposes, most projects are not large enough for that to be necessary. Moist clay would also be used for projects that start with slabs rolled from the slab roller – primarily used in the younger grades for slumping shallow bowls or making impressions.
Stiff clay: This is clay that is dried just enough to stand on its own without sagging. This would be used for constructing boxes and upright items. Stiff clay will have cleaner lines/edges when cutting, using cookie cutters, or carving than moist clay. To work with stiff clay, it must be rolled and left out for several hours or more depending on humidity levels in the environment. If clay is left out too long and becomes too stiff, you can spray it with water, cover it and let it stand until the water is evenly absorbed.
Leather hard clay: This is clay that is too dry to bend without cracking or breaking, but is still flexible enough to carve into.
Bone dry: Items take 14 days to be completely dry. They MUST be bone dry and room temperature before they go into the kiln – they will feel warm when held against your cheek. Items are VERY fragile at this state!
