Ceramics
Ceramics
Ms Callaghan
Final Exam Study Guide
Air bubbles trapped in clay will cause your work to blow up or crack in the kiln during the bisque fire
When air gets trapped inside your clay steam will accumulate in the bubble causing it to expand and burst through the clay. This will not only destroy your own project but the ones around it as well. Make sure you take photos of your project prior to each firing.
When using recycled clay, you should always wedge your clay prior to using it. Wedging helps to mix the clay so it has consistent moisture and it pushes out air bubbles. There are many wedging techniques but I primarily use the ram’s head wedging technique.
Score & Slip- Always score and slip when attaching 2 pieces of clay together. Scoring is the process of scratching up the surface of the clay with a scoring tool, needle tool, or fork. Adding slip will help strengthen the bond. Always blend and smooth around the edges to ensure a strong bond.
Five Stages of Clay: Slip, plastic, leather hard, bone dry, & bisque
Shrinkage: As Clay goes through each of these stages, it is losing water due to the drying process. This loss of water causes your clay to shrink. Every kind of clay has different shrinking rates and it is important to be aware of this especially if you are making parts that are meant to fit together.
SLIP - Slip is often referred to as ‘potters glue’ as it is clay but with water added to it to give it a paste-like consistency. Slip can be used for decorative applications but is most commonly used to join two pieces of clay together.
PLASTIC- When clay is at its plastic stage it means that it is still too wet to really hold more than a basic form. At this stage, it is the best time to create a pinch pot and apply any stamped decorations.
LEATHER HARD- When clay has reached its leather hard stage, it is a great time for slab construction, carving, and adding fine details and finishing touches.
BONE DRY- When clay has reached its bone dry stage it is at its most fragile state. The majority of the water in the clay has evaporated from it and should no longer be handled / handled carefully and limitedly. It is also ready for its first kiln firing at this stage.
Greenware- This refers to any clay body that has not yet been fired.
Bisqueware- This refers to any clay that has been fired once but has not been glazed yet.
Three Handbuilding Techniques: Pinch, slab, & coil.
You should always work on a porous surface when handbuilding (like canvas or wood) so that your clay doesn’t get stuck to the surface of the table.
To make a pinch pot, one inserts a thumb into a ball of clay and continually pinches the clay between the thumb and fingers while rotating to thin out and raise the height of the vessel. Pinching can deliver a pleasingly organic look, but can also yield beautiful, refined results. Qualities of a strong pinch pot include even thickness of all walls of the pot, no cracking, smooth walls and lip // only intentional marks left behind, a round base that shows it was properly made.
Coil building is a forming method that uses ropelike coils of plastic clay, assembled in successive courses to build up a wall of a vessel or sculpture. Qualities of well made coils include even widths, no cracking, and smooth surfaces.
The slab technique starts with smooth slabs of clay that are then formed around molds or shaped by hand. Although it can be used to create many of the same shapes that are achievable on a wheel, slab building also allows the potter to create more angular shapes that are more challenging to make on a wheel.
Surface Design Techniques
For Greenware
Incising: Whenever you are pressing into greenware with a tool to create a design. When you ‘draw’ on your clay. Clay should be leather hard for this method.
Excising: When you use a loop tool to ‘draw’ on or create a design in your clay but the clay is being removed to create that design. Clay should be leather hard for this method.
Stamping: When you use a premade stamp or any item with texture to press into your clay and leave an imprint. Stamping works best when your clay is more plastic than leather hard especially with fine detail.
Sprigging: Sprigging or sprigged decoration is a technique for decorating pottery with low relief shapes made separately from the main body and applied to it before firing. Usually thin press moulded shapes are applied to greenware. The resulting pottery is termed sprigged ware, and the added piece is a "sprig". Clay should be in the early stages of leather hard for this method.
Piercing: Using a tool (such as a needle tool, small knife, or piercing tool) to cut fully through the clay. Clay should be leather hard for this method.
Burnishing: The process of taking the back of a metal spoon, smooth rock, bone, or glass and rubbing it lightly on the surface of the clay to compress it and give it a high sheen. Burnishing is done when the clay is at its leather hard stage and after it is fired it is very shiny.
Slip Trailing: A decorative technique that is the application of slip or underglaze to a clay surface using a bottle or other flexible vessel
with a pointed tip. Usually a small squeeze bottle (think of a classic ketchup or mustard bottle).
Underglaze Techniques
For Greenware and bisqueware
Brushing or Painterly: Brushing: The process of brushing paint onto clay just as one might paint; use of paint brushes to create imagery or painterly designs.
Sgraffito: The process of painting underglaze into greenware and then carving or excising through the colored underglaze to reveal the color of the clay underneath.
Layered Sgraffito: The process of painting multiple layers of variously colored underglazes into greenware and carving or insizing through the underglazes to reveal multiple colors and/ or the color of the clay body underneath.
Mishima: Also known as inlay, this is a process in which one carves, incises, or excises the clay and then fills the carved space with a colored slip or underglaze. The colored slip or underglaze is left to dry and then wiped or scraped from the rest of the pottery leaving a level surface with only the carvings filled with the newly applied color. This process originated in Korea.
Underglaze Transfer: Underglaze transfers are designs that can be bought in many different colors and designs. It is underglaze that is printed onto thin paper that you can apply to smooth, flat surfaces and press with a damp sponge allowing the underglaze to be transferred from the paper to your artwork. You can also make your own transfers by painting or trailing underglaze onto newsprint or other thin paper. It creates a different kind of texture and image than simply applying the underglaze onto your work with a paint brush.
Underglaze Stain: A technique used to help bring out / emphasize texture. Done on bisqueware by applying a layer of underglaze on desired area and then gently wiping it away with a damp sponge so that underglaze only remains in the crevases of the texture.
Kiln Firing
Kiln - A kiln is a type of furnace or insulated chamber that can produce a lot of heat. Ceramic works are generally fired twice in a kiln - once for a bisque fire and once for a glaze fire. Kilns can reach up to temperatures over 2500 degrees, hot enough to melt glass and some metals.
Bisque- The first kiln firing is called a bisque fire. We bisque fire our clay to CONE 04 (1945 degrees fahrenheit) . Clay is put into the kiln and it is brought up to almost 2,000 degrees (your oven at home may go up to 500 degrees and that’s pretty darn hot!), when this happens clay goes through a chemical change. When clay comes out of the first firing it is then referred to as bisque ware. The object is still fragile but is almost like stone and is no longer sculptable in any way. It is now ready to have a glaze application added to it.
Glaze- Glaze is a mixture of powdered minerals with water mixed into it to make it a liquid that can be applied to ceramics using various techniques. Glaze is primarily made up of silica (essentially ground up glass), which is what gives glaze its shiny, glass-like appearance after the glaze firing. In addition glaze has flux (a material that can promote lower melting temperatures) and alumina (a material that helps the glaze stick // bond to the clay). The other minerals that are added to glaze are what gives it its colors and textures; for example, red glazes usually contain oxides (think iron oxide and how rust has a reddish color) and blue glazing might have cobalt.
Glaze Fire- When we glaze fire our work in the kiln we fire to CONE 05 (1888 degrees fahrenheit).
When glazing, you should always add 2-3 coats of the glaze while allowing it to dry inbetween coats. Always mix your glaze prior to using it.
Glaze should never be applied to the bottom of our work because it will fuse to the kiln shelf. You should always make sure your glaze it at least 1/4th of an inch above the foot of your work. Many potters use wax resist to help keep their foot clean. The process of not glazing the foot of work is also called dry footing.
Clear glaze: Pink when applied but clear after fired. If applied too thick it will have a ‘cloudy’ appearance.
Crystal Glaze: Crystal glazes are a kind of specialty glaze that have bits of ground up glass in them that cause the effect of bursts of color when fired.
Glazing Techniques: Brushing, dipping, pouring, sponging, spraying, trailing
(there are more than this but we won’t even get to use all of these)
Brushing- Same technique as painting where you use a paint brush to apply the glaze but the color will not be accurate until the glaze is fired.
Dipping- When you use tongs to fully submerge the ceramic piece in glaze in a large bucket.
Pouring- When you fill a small cup with glaze and pour it over the ceramic piece.
Trailing- Using a squeeze bottle to apply glaze to create various designs.
Underglaze: Underglaze is a medium that can be used on greenware or bisqueware to apply color to a piece of pottery. Unlike glaze, underglaze will fire matt instead of glossy. Underglaze is almost always very opaque unlike glaze which often has a certain amount of transparency. Just like when applying glaze, you should always add 2-3 coats of the underglaze while allowing it to dry inbetween coats.
Underglaze Techniques: Sgraffito, layered sgraffito, underglaze transfer, mishima, slip trailing, brushing, underglaze transfer (there are more than this but we won’t even get to use all of these)
Sgraffito: In ceramics it is the process of painting on underglaze, allowing it to dry, and then scratching or carving through the surface to reveal the original color of the clay body.
Layered Sgraffito: Decorative process of painting multiple layers of different colors on a clay body and then scratching or carving through the surface to reveal the various colors beneath and/ or the original color of the clay body.
Mishima: A technique of inlaying slip, underglaze, or even clay into a contrasting clay body, the main clay body of the pottery piece. Typically done by carving into leather-hard clay and then filling the carving space with underglaze and allowing it to dry. After drying, the clay body would be whipped or scrapped inorder to leave a smooth, level surface revealing the carved space now filled with new color.
Slip Trailing: A decorative technique that is the application of slip or underglaze to a clay surface using a bottle or other flexible vessel with a pointed tip. Usually a small squeeze bottle (think of a classic ketchup or mustard bottle).
Brushing: The process of brushing paint onto clay just as one might paint; use of paint brushes to create imagery or painterly designs.
Underglaze Transfer: Underglaze transfers are designs that can be bought in many different colors and designs. It is underglaze that is printed onto thin paper that you can apply to smooth, flat surfaces and press with a damp sponge allowing the underglaze to be transferred from the paper to your artwork. You can also make your own transfers by painting or trailing underglaze onto newsprint or other thin paper. It creates a different kind of texture and image than simply applying the underglaze onto your work with a paint brush.
Ceramic Tools:
Rib Tool: Can be metal, wood, or rubber. Used for wheel throwing and hand building.
Incising Tool: Looks similar to a needle tool but has a ball on the tip.
Loop tool: Used for exercising clay, usually a wooden handle with a metal loop on the end. Also called a ribbon tool.
Banding Wheel: A metal wheel that elevates your work off of the table and turns so that you don’t have to handle your work as much.
Needle tool: A tool with a handle and needle attached to the end.
Fettling knife: A very thin knife used for cutting clay.
Functional work: Something you might use regularly like a cup, mug, plate, or bowl. It serves a purpose in everyday life.
Non-functional- Something that is purely decorative like a painting. It is not meant to be handled regularly. Does not serve a purpose.
Compress: Pushing the clay down and together, forcing the particles of clay closer together.
Stages of clay
Greenware and Bisqueware
Cone 04 and Cone 05
Glaze fire and Bisque fire
Compressed clay
Sculpture in the round
What it is
Score and slip
Glossy and Matt
Transparent vs Opaque
Shrinkage
Wedging
What it is and how to use it
2 main reasons it is done
Ram’s head wedging
Functional vs Non Functional work
Glaze brushes vs Other brushes
Templates
What they are and how to use them
Dry footing
Clear glaze
What it looks like and how to apply
Beveling
Wheel throwing (just what it is)
Chemical Changes of clay and glaze (general understanding)
Wax resist
What it is and how to do it
Foot and lip
Ceramic Tools - what they are and how to use them
Ribtool
Incising tool
Loop tool
Banding wheel
Needle tool
Fettling knife
Surface Design Techniques
Piercing
Sprigging
Slip trailing
Incising
Excising
Stamping
Underglaze
Mishima
Sgraffito
Underglaze Stain
Newsprint transfer
Painterly
How to recycle clay (including bone dry clay)
Glaze
What it is and how to use it
Flux, Alumina, Silica
Crystal Glazes