Ceramics 102
Overview & Purpose
In this class you will learn how to throw pots on a pottery wheel, while making a few vessels.
Project
Three vessels.
Duration
9 hours - 3 hours a week, for 3 weeks.
Prerequisites
Required: none
Recommended: Ceramics 101
Equipment & Materials Needed
Equipment (per student / instructor)
Pottery Wheel
Pin Tool
Loop / Ribbon Tools
Wooden Modeling Tools
Paintbrush
Sponge
Materials (per student)
Clay (300-400g for the mug, 800-900g for the bowl + 100g for the practice puck recycled)
Underglaze
Wax Resist
Clear Glaze
Safety Considerations
Recommended:
Remove dangling jewelry
Tie back long hair
Lesson Sequence/Teaching Guide
Week 1:
Studio Orientation (15 minutes)
General Rules
Welcome to the Ceramics Lab! We have a few rules to keep this space tidy, and minimize breakage of people’s projects.
No outside clay. Clay must be purchased from MakerLabs. This will ensure that we know what is going in the kiln. Different clays can fire at different temperatures, and if the settings are used for the wrong type of clay, work can cause damage to the kiln, or explode and damage other’s projects.
Always clean up after yourself. All tools should be cleaned and put away, and tables should be wiped down after each use.
Do not use the utility sink that is hooked up to plumbing. We want to prevent clay from going down the drain and clogging up our pipes. Use the sink that is located in the Ceramics Lab when needed. Make sure there is a bucket under it to drain into.
No sanding. Sanding creates silica dust that is very bad for your lungs. We do not want it floating through the space, so no sanding is allowed in the Ceramics Lab. If it’s absolutely necessary that you sand your work, you must do so in the sanding booth in the WoodLab, with proper dust collection.
Those using the studio outside of class times, must store their work and any items they wish to store in the studio in their designated storage shelf.
MakerLabs is not responsible for any projects or materials that are left in the Ceramics Lab or any damage that occurs upon firing work. It is your responsibility to make sure that your clay is properly covered when needed, and pieces are made properly to prevent damage to your own and other student’s work when firing.
Initial and date your work. Once projects are fired, they will be returned to members’ storage shelves. Those participating in classes will be notified once their projects are ready for pick-up. We aim to have projects ready within a month of taking the class. Students must pick-up their projects within two weeks of notification. Failure to do so may result in disposal of your project.
Fees
Bag of Clay: $50/10kg bag. This includes the use of underglazes, glaze, and firing. There is no limit to how much clay you can purchase in a month.
Ceramics Lab Drop-In Rate: $30/day
Different Stages of Clay (15 minutes)
Wet Clay
This is the form that clay comes in when first purchased. Wet clay must be wrapped in plastic to keep it in a usable state, and prevent it from drying out. It typically comes in 10kg bags, and can be cut in pieces as needed to produce many different pieces. Both handbuilt and thrown pieces start out using wet clay. Clay contains about 20% moisture, and will shrink once dry / fired.
Slip
Slip is clay that has had water added to it to make it into a liquid or paste. Slip is most commonly used when joining two pieces of clay together (ie. a handle to a mug body). It can also be made extra runny and used for “slip casting” where slip is poured into a mould, which is then fired, to cast pieces of pottery.
Leather Hard
When wet clay has dried slightly, but is not fully dry, it is called “leather-hard”. At this stage, you can trim and carve decorative elements into your work. Leather hard is also the state where you would use underglaze.
Dry (aka Greenware)
When clay is fully dry it is also known as Greenware. It is most fragile at this state, and needs to be handled carefully to prevent breakage. Once clay has reached this state, it is ready to be bisque fired.
Bisque
Bisque is clay that has been fired once. This changes the chemical and physical properties of the clay. Clay is still hard, but porous enough that it will absorb glaze. At this stage, glaze is applied for the final firing. Projects can be dipped in glaze, or have work poured in / over it. Water is absorbed into the clay, making the glaze stick to the surface of the pot.
Glaze Ware
After a second firing at a higher temperature, the clay and glaze have fused together to make a finished product that has a non-pourous surface. At this point, your project is ready to use.
Different Types of Clay
Earthenware Clay
Earthenware clays are low fire clays. The temperatures at which low fire clay is fired at ranges from between 1479 and 2109F (804-1154C). A lot of earthenware clay is red or orange, because it has a high content of iron oxide.
Stoneware Clay
Stoneware clay fires at higher temperatures than earthenware clay, and it is tougher than earthenware clay once fired.Compared to earthenware clay it is denser, more resistant to breaks and chips, and less porous. Stoneware clay comes in different colors, but it’s often grey when it is moist. The depth of color will vary from a pale grey to quite a deep grey color. It is often used to make dinnerware.
Porcelain Clay
Porcelain is a high fire type of clay, which means that it usually fires at temperatures from 2232F (1222C) upwards. Once fired, porcelain is normally white and can have a translucent appearance. It can be shaped into thin, delicate forms, and is very dense and hard.
Pottery Wheel Orientation (15 minutes)
Parts of the Wheel
Preparing the Clay
As covered in Ceramics 101, when starting with clay, we need to work it before we can begin building with it.
Use either the Spiral or Rams Head methods of wedging your clay. Cut clay enough to see that there are no air bubbles.
Centering your clay
If this is your first time centering, use around 100 g of clay.
Form your wedged clay into a cone or ball. Round the bottom of your cone, by rolling the cone against the table. A convex bottom is necessary to ensure that no air bubbles are trapped between your piece and your wheel head.
Raise clay roughly to eye level and slam it down onto a dry wheel head. Use your fingers to seal the edges of your clay to the wheel head or firmly rub the clay down against the wheelhead.
Wet the clay with your fingers, not your sponge. Your clay should feel lubricated but not soaked. Use your foot to set the wheel speed.
Place your dominant forearm against the catch basin or your thigh anchoring yourself.
Press the side of your hand against the clay with your pinky applying pressure against the clay so that it is leaving an indentation and your clay looks like a dome. (NOTE: If you are left handed, you will need to get the wheel to run in reverse)
Use your non-dominant hand to apply pressure on the top of the clay.
You will know your clay is centered when:
You can remove your anchoring forearm, relax and your arm will stay reasonably still.
The fingertips on your dominant hand will stay relatively still when running along the clay.
Form into a cylindrical puck 1 - 2 cm high this will be your practice puck for trimming next week.
Alternative Centering/Wedging - Coning
Coning is another way of centering your clay and works better for larger pieces of clay. It also helps eliminate any air bubbles in your clay.
Apply pressure at base and middle of your clay so that it wants to escape upwards. This should form a cone.
Squish the clay down using your thumbs and a gentle forward pressure. DO NOT apply pressure directly to the top of the cone, as this will create an awkward lump at the top of your dome of clay.
Each time you form the clay into a cone check to see if the top of your cone is running smoothly with no wobbles. When your cone no longer wobbles your clay is centered.
Common Beginner Mistakes
Not getting close enough to the wheel - You want to be as close to your wheel as possible, anchoring your forearm against the basin. You should also lean directly over your piece. This will also help you see when you are centered.
Too much water - Clay should be lubricated and smooth to the touch, but not soaking in water. A good limit to place on yourself is no more than ¼ cup of water per piece. This also helps with clean up.
Too little pressure - You need to move the clay not have the clay move you.
Too much lateral pressure from the dominant hand - This will cause the piece to unstick from bottom, or become uncentered.
Centering for too long- Your clay is getting too wet. Try pulling the sides to test how off center your clay truly is.
Pulling the sides of your pieces
NOTE: Despite the name of the practice, you are actually squeezing so that clay moves upwards not “pulling” the clay up.
After you are sure your piece is centered and the base of your dome is as wide as you would like on your piece, find the center of your piece and with two thumbs make a v-shaped indent. Add water as it dries out.
Make the indent all the way to where you want your bottom. Typically this is ¾ to 1cm from the wheelhead. Make sure the rest of your fingers prevent the clay from spreading wider than the base of your pot.
Use your thumbs to turn the v indent into something more cylindrical. The inner wall should be 90 degrees with the base. Use your thumbs to smooth out the bottom if necessary.
You should have what resembles a pot with thick walls. It’s time to thin them out. Take your index finger on your dominant hand and bend it to create a flat surface as seen below. Put your index finger on your dominant hand inside your pot and apply even pressure so it presses into your bent index finger on the outside. Squeeze gently, and decisively upward. This can be repeated.
Shape your piece into a cone. This resists the clay’s temptation to spread out with the circular motion of the wheel.
For the mug, shape your piece into a cylinder as high as it will go. Making cylinders is good practice for throwing.
For the bowl, shape your piece into a cylinder then the desired bowl shape. Take care that the base of your bowl is wide enough to support it. Do not thin out the rim until the very end.
If the top of your piece is uneven you can trim it using a potter’s pick. Insert the potter’s pick with the pick pointing away from the direction of the motion of the wheel. This will carve the top of the piece off.
You can smooth your pot using a kidney scraper or a dry sponge. Make sure the lip of your vessel is smooth and not sharp. You can smooth it out using your fingers, a sponge, or a leather chamois.
Removing your pieces
Pour enough water on the wheel head so that it forms a puddle.
Slide your wire cutter in between the wheel head and the base of your piece. You should also introduce a bit of water, so that your piece can hydroplane off the wheel.
Remove the drip tray and press the bottom of the piece so that it glides off the wheel and the base of your piece lands into your open palm
Demo - Fixing a Bat to your Wheel
A bat is an alternative surface to work on the wheel. You fix the bat to the wheel by using clay to glue it down.
Grab a ball of clay and put it on your wheel.
Roughly center your clay and flatten it. Take care that your clay pancake is roughly level
Create an indent in the centre. This will help suction your bat onto the wheel.
Grab your bat and place it on the wheel head. Don’t worry too much if it isn’t centered perfectly, your clay won’t care.
Note: Many wheels have holes in them that allow you to fix a ceramic bat to your wheel, but ours doesn’t have one of these.
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Cover your project up with a plastic bag and put on the shelf for next week. This will make sure the clay doesn’t dry out too fast, which would cause it to crack. It should be at leather hard stage by the following week.
Any left over clay can be recycled into other projects. See end for clean up tips.
Note: Make sure students prepared a centered disk approximately 1.5 inches high for each student to practice trimming with. They should be leather hard by next class.
Class 2 - Trimming:
Now that the pieces have dried a bit, they will be at the leather hard stage. At this stage, the bases of your piece can be trimmed. Most importantly it is time for you to add a foot to your vessel. Trimming allows your piece not to be so heavy.
Seeing how thick your base is
Use two straight objects in the shape of a T to figure out how thick your base is. Place one vertically inside your pot and one horizontally over the rim of the pot.
Grab so they are still connected and reorient so that the horizontal stick lines up with the rim of the pot and the vertical one is outside. The gap from the wheel to the base is how thick your base is.
Recentering your piece
DO NOT LEAVE YOU PIECE UNSECURED. It can fly off and hit your drip tray.
Use the guidelines on the wheel to figure out where to put your piece. Note this will be harder to do if your piece wasn’t perfectly centered to begin with. Spend some time on this step.
Use a pencil (or potter’s pick) and lightly touch it against the sides of your vessel. Note that the pencil should face away from the pot’s direction of movement. Move the piece away from where the pencil touches.
Find the middle of your piece and put a dot with your pencil.
Draw two concentric circles, by placing the pencil with the wheel spinning. A little larger than you want your foot to be on the base of the pot. Make sure they are centered.
When your piece is centered use wet clay brackets to hold down your piece. The more the better!
Trimming your pot
Use the round base of the pear tool or ribbon tool to carve the outside of your foot. Be sure to apply constant pressure. Only carve up to the outside circle. You can also use the tool to smooth out the sides.
Use the point of your pear tool to dig as deep as you want your foot on the inner circle.
Use the pear tool or square ribbon to carve away the center. Try to keep this space roughly flat.
Bonus: You can carve away clay on the sides to add a nice textural decoration.
Practice Puck: Practice carving into a leather hard disk prepared for each student. Students practice bracketing as well.
Video on centering and trimming your puck
Class 2 - Waxing, Using Underglaze, and Glazing:
Using Wax Resist
To make sure the clay doesn’t stick to the kiln, all pieces must have wax applied to their bases. The wax will burn off in the kiln once fired.
The wax will be applied with a brush. To help preserve the bristles, dip the brush into cold, soapy water before using the wax resist.
Apply the wax to the entire bottom of the mug, and ¼” up the sides. Make sure your brush isn’t loaded with wax, as any excess can drip down the mug, and is difficult to clean off. Be careful not to get the wax anywhere you don’t want on your mug, as the glaze will not stick.
You can use wax to also make decorative designs. Wax can be applied to the entire mug, carved into, and glaze applied to the negative space. Any excess glaze can be cleaned off with a sponge.
After applying wax, wait 5 at least minutes for it to dry, before applying the underglaze.
All wax brushes should be kept separate from glaze brushes. To clean the wax brushes, use a small container, pour boiling water on the brushes, and mix them around in the container to clean off the wax. Remove the brushes once they’re clean. Wait for the water to cool, the wax will solidify once cooled, and can be disposed of. Do not pour wax down the drain.
Working with Underglaze
Underglaze is applied to work that is leather hard, using a brush. Make sure to stir the underglaze before applying it. At least two coats should be used when applying underglaze. There are a few different techniques that can be used when applying Underglaze.
Scraffito
After applying underglaze, wait until the glaze is dry enough so it is firm to the touch. Using the pin tool, or modeling tools, carve into the clay, to reveal the natural colour below. Make sure to remove any excess clay from your tool when carving.
Layered Scraffito
This technique is done by using multiple colours of underglaze, painted on top of each other. When applying each layer of underglaze, wait a few minutes for the underglaze to dry before applying the next colour. Once it’s dry, use a carving tool to carve away the clay and reveal the layered colours.
Inlay
Carve into your clay, making sure there aren’t any raised edges. Using a brush, fill the carving with underglaze. Once it’s dry, gently wipe away any excess glaze.
Painting
Using the underglaze, you can paint the mugs the same way you would use regular paint. Make sure not to contaminate the glaze containers with other colours. The glaze can be applied using a paintbrush. If you choose to mix your own colours, use a palette. Just note that because glazes are made using different minerals, traditional colour theory may not apply, and mixing colours together might not give you the desired result. (ie. Red and yellow together might not make orange)
After applying the underglaze, the mug will need to finish drying. Once it is dry, it will be ready to bisque fire.
Cleaning Up Underglaze
After glazing, brushes can be cleaned with soap and water. Place soap in your hand, and swish the brush around in your hand. You will need to repeat this process a couple of times until the brush is clean. It will be clean once the brush doesn’t change the colour of the soap. Make sure to rinse any soap off of the brush.
Applying Clear Glaze
After bisque firing has been completed, a clear glaze will need to be applied to the mug, prior to the final firing. Wax the bottom, and using a brush, apply the clear glaze.
Once the glaze is dry, the mug will go through it’s final firing, and students will be notified once the mug is ready to pick-up. We aim to have all work ready for pick-up within a month.
Cleaning up the Studio
Throwing pots generates a lot more mess than hand building. This is because throwing generates quite a lot of slip. Contaminated slip can be disposed of in the yellow bin. Please do not throw it in the disconnected sink (this generates bad smells!) or utility sink (this clogs our drains!). Besides cleaning up surfaces with a damp towel here are some more tips to keep the studio clean.
Cleaning the wheelhead
To clean the wheelhead use a wet towel and run the wheel for a few rotations. This should quickly and efficiently clean your wheelhead.
Limit your water
It’s wise to limit yourself to only ¼ of water for a piece 2 pounds or less. Not only will this make your piece stronger, you won’t generate as much slip that needs to be recycled.
Clean up your slip drips
Slip drips should be cleaned up with a damp paper towel and then thrown away. Cleaning up slip drips with a mop or a regular towel will just spread the clay around creating a streaky mess.
Work tables
Work tables should be scrubbed with a wet towel, making sure any bits of clay are removed. Any clay that dries and hardens can get into other people’s work and could cause it to crack / explode when fired
Have a wash bowl
Have a bowl of water to clean things before washing things in the sink. You can even use a sponge to wipe down larger surfaces, like your drip tray. If wash bowl water becomes too dirty you can transfer it to the yellow bucket.
Mop up
When mopping please wash out your mop frequently. Mop areas of only 2 square feet before returning it to the bucket washing out your mop. This ensures that slip isn’t transferred everywhere around the studio
Recycling Plan
We are currently working on a process to better recycle slip, but it will most likely resemble something like this. Slightly damp clay can have holes poked in it and be wrapped to be used later. Studios that have a high volume of users generally invest in something called a pug mill which helps recycle clay.
Reusing clay
Extra leftover bits of clay can be recycled and used for future projects. However, clay doesn’t like to go back together easily if it’s at different levels of dryness. If you have leftover clay, try and form it into a big block, and slam it into a solid shape. Poke some holes in it, spray with water, cover in plastic, and let it sit overnight, making sure the plastic is sealed. After it has sat overnight, wedge the clay to prepare it for use.
Schedule
Week 1:
0:00 - 0:05: Welcome and Intros
0:05 -0:20: Studio Orientation
0:25 - 0:35: Intro to the wheel and centering your clay (making your practice puck)
0:40 - 1:00: Making cylinders
1:00 - 1:20: Making your mug
1:20 - 1:40: Making your bowl
1:40 - 2:00: (Demo) Using a bat
2:00 - 2:30: Clean Up
Week 2:
0:00 - 0:20: Practice foot carving and Demo
0:20 - 0:40 Trimming / carving into work
Week 3:
0:40 - 1:40: Waxing and decorating mug
1:40 - 1:45: Talking about clear glazing and reminding students about Ceramics Lab fees.
1:40 - 2:00: Clean up + Mop
Resources:
Resources: