CERAMICS ESSENTIALS
HERE'S THE THEORY
Ceramics Essentials will teach you the fundamentals of using the casting Lab. It is divided into two parts, an online part and a practical.
The course starts below by taking you through some basic steps you need to learn to start using the lab. It will also introduce you to the most common materials used; plaster, clay and concrete, their properties and how to use them.
The practical part of the course will require you to complete 2 challenges:
- Make a clay mould of a tile, prepare it for casting. Mix plaster, and cast the tile. Clean up ready for the second challenge.
- You will then mix a batch of concrete for creating a sample for testing its material properties (you can use this sample in the Material Testing Essentials).
Please be sure to concentrate when you go through the following points, as you'll need to pass a short quiz before you can book a place on the practical part of the course.
Everything you need to know to complete the practical part is contained within this online part. Watch the videos carefully as they demonstrate what you will have to do yourself in the Lab. we recomend watch all the video again prioir to starting your practical session.
The booking form immediately follows the quiz - IF you get enough of the answers right!
You should only need about 5 minutes to go through the points, and 5 minutes to complete the quiz.
Before you can use the Casting Lab you need to know what you can use the lab for. The ceramics lab is where you can cast plaster and concrete, use Mod-Roc and model using clay. These are the main materials that the ceramics lab is used for and these can be purchased from the Lab Shop. Silicone and resin cannot be used in the ceramics lab. Silicones and resins must be used in the Spray Room. Other materials such as papier mache are suitable but please check before using.
Are you dressed appropriately, according to the Lab Dress Code?
Are you wearing safety glasses, and any other PPE if required?
Are you allowed to use the machine, according to the Traffic Lights?
The Hazards involved in the lab are from the materials used rather than the machinery. Read carefully as you will be tested.
Plaster:
- HAZARD: When curing, plaster creates an exothermic reaction. If you cast plaster around your hands in a bucket, the plaster will start to harden and heat up, your hands will start to cook, and will not be able to remove them. You will loose your fingers. CONTROL: DO NOT CAST YOUR BODY PARTS.
- HAZARD: For people with very sensitive skin, plaster can dry your skin. CONTROL: Wear gloves if you have sensitive skin.
- HAZARD: Working with plaster can ber very messy. CONTROL: Small volumes of plaster will always be safer and cleaner. Larger quantities (more the 3kg) should only be used with staff assistance.
Clay:
- HAZARD: When dry the dust is hazardous to your lungs so do not sand or scrape dry clay. CONTROL: Only use clay when wet. DO NOT SAND DRY CLAY.
- HAZARD: Toxic fumes emmitted from the kiln. Once the clay has dried it gets fired in a kiln. COTROL: Only clay can be fired If you want to fire your clay you cannot add anything into the clay as this will burn in an unpredictable way.
Concrete:
- HAZARD: Cement is very corrosive to your skin and eyes. CONTROL: You must wear heavy duty gloves that we provide, wear glasses at all times and avoid making the dry material airborne.
In the Casting Lab you can use many materials. The three main materials and the three covered in the Essentials are Plaster, Clay and Conrete.
Plaster:
- Plaster is bought as a fine white powder (Calcium Sulphate Hemihydrate) when mixed with water becomes a liquid similar in consistancy as double cream. The water starts a chemical reaction that converts it from a liquid to a solid, all under an hour (it might take several days to fully cure and dry out). This mean plaster is a great material for casting with.
Clay:
- Clay is is a fine grained natural soil material dug from the ground. It is putty like with great plasticity. Becuase of this plasticity it is used in many ways; potters 'throw' it on a wheel, it can be rolled cut, coiled and carved, it can be pressed into moulds or thinned to a liquid and poured into plaster moulds. To convert it from a soluble clay to a ceramic, once 'bone dry', it is fired in a kiln above 600 C. After this it can be glazed with a huge variety of colours. The glaze is a coating of a liquid suspension of glass minerals which are then refired at 1200 C, creating a glass like coating on the outside of the ceramic body. Bricks are unglazed fired clay, your tea cup is fired clay which has been glazed.
Concrete:
- Concrete is the second most used material on earth after water. It is a combination of cement (the binder) sand (filler) and course aggrigates (for strength). Like plaster, when water is added it begins a chemical reaction that converst it to a solid. Unlike plaster it is a slow process taking upto 24 hous to solidify and 28 days to get to stength. It can continue to cure for years after.
1st
After you have completed your Essentials, to use the lab, hand over your student card at the lab shop and explain what you want to do. (for example cast plaster, or concrete, or model with clay) in return the Lab Assistant will loan you the tools you require and the number of the bench you can work at. These tools must be returned cleaned after use. (if you are here for Essentials go straight to the casting lab as the equipment is set out for you)
2nd
Before you enter the room you must put on protective glasses. Once inside you can put on an apron, this is optional but will protect your cloths
3rd
Go to your allocated bench and place your tool underneath (For the Essentials sessions your tool will be already there for you)
When making a mould for casting there some fundamental principles.
- It must be water tight. The plaster will be poured in as a liquid, therefore it must remain there while it cures, and not leak out through holes or gaps.
- It must be the negative of what you want.
- There can be no undercuts
- You need to get the cast out of the mould. If the mould is made from an absorbant material a release agent will be needed. Rigid materials such as foam can be diffuclult to remove.
water tight mould
A gif of a good and bad mould
negative space
negative positive
undercuts
no undercuts
MIXING PLASTER: When mixing plaster there are some fundamental principles.
- It must be mixed to the correct ratio of water to plaster (1:1.3). This can be done by measuring it by weight or we teach you to add the plaster slowly to the water until it stops absorbing the plaster, as seen in the video below, this is standard practice when mixing plaster.
- Always add the plaster to the water
- Do not pour waste plaster down the drain. It will cure, harden and block the drain. Pour it into the bucket in the sink.
correct water ratio
A gif or correct and incorrect water ratio
Add plaster to water
Disposal
Do not pour down the drain
HAND MAKING WITH CLAY: When making with clay there are some fundamental principles.
- Roll your clay onto fabric to stop it sticking to the board.
- Stick parts together with 'slip' (a slurry of water and clay, you can make your own or find it on the shelf in the lab)
- If you want to keep working on your clay keep it damp by wrapping in plastic, do not let it dry out.
Roll onto fabric
Rolling clay
How to stick clay together
with slip
Do not allow to dry
Keep wrapped in plastic
A summary of Essentials Challenge. Watch the four video below.
Make a mould of a tile
Insert two boards provided into the bench. Make 77mm tile from clay (the negative of what you want to cast).
Prepare mould
box in the mould using the cottle boards provided.
Mix Plaster
Return the flat boards and get ttwo trays to mix and pour plaster.
Mixing Concrete: When mixing concrete there are some fundamental principles.
- Roll your clay onto fabric to stop it sticking to the board.
- Stick parts together with 'slip' (a slurry of water and clay, you can make your own or find it on the shelf in the lab)
- If you want to keep working on your clay keep it damp by wrapping in plastic, do not let it dry out.
Make a mould of a tile
Insert two boards provided into the bench. Make 77mm tile from clay (the negative of what you want to cast).
Prepare mould
box in the mould using the cottle boards provided.
Mix Plaster
Return the flat boards and get ttwo trays to mix and pour plaster.
If you think you need to, go back and review these previous steps. If you are sure you've taken them all in, then please now proceed to the Quiz to see if you've got it!
If you want to progress further please register first!
