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Lesson 7 of 9
  • Year 10

3D Design: plaster casting

I can experiment with three plaster casting methods and show how form, surface and construction interact.

Lesson 7 of 9
New
New
  • Year 10

3D Design: plaster casting

I can experiment with three plaster casting methods and show how form, surface and construction interact.

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Lesson details

Key learning points

  1. When casting, plaster is poured directly over a model to create a mould.
  2. When casting, the model is coated with a release agent to prevent sticking.
  3. A mould can be created in two halves, allowing for more complex shapes.
  4. Applying a thin layer of plaster (poured or brushed) to a model and building up several layers creates a solid shell.

Keywords

  • Mould - a hollow form used to shape plaster

  • Release agent - prevents plaster sticking to the model

  • Casting - pouring a liquid material (like plaster) into a mould, where it hardens into the shape of the mould to form a replica

Common misconception

I can just pour all the plaster at once and it will work.

Plaster heats as it sets and pouring too much at once can trap air, cause cracks or damage the model. Layering ensures detail and structure.


To help you plan your year 10 art and design lesson on: 3D Design: plaster casting, download all teaching resources for free and adapt to suit your pupils' needs...

Have clearly labelled example stations for each technique. Use small, manageable forms for faster drying. Demonstrate the proper mixing ratio of plaster to water and health and safety, including wearing face masks and gloves.
Teacher tip

Equipment

Plaster of Paris, containers, clay, brushes, petroleum jelly, objects for moulds, PPE (gloves/masks), aprons, mixing tools, sketchbooks and pencils.

Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Prior knowledge starter quiz

Download quiz pdf

6 Questions

Q1.
What is plaster casting?

Painting patterns onto clay surfaces
Correct answer: Pouring or brushing plaster around an object to capture its shape
Carving shapes directly into stone
Mixing plaster with clay to make bricks

Q2.
True or false? Plaster must never be washed down the sink because it hardens and can block the pipes.

Correct Answer: True, Correct

Q3.
What is the role of a release agent in plaster casting?

To make plaster set faster
Correct answer: To stop plaster from sticking permanently to the object
To change the colour of the plaster
To make plaster softer

Q4.
Which of the following are three types of plaster casting methods?

Correct answer: Direct pour
Correct answer: Shell casting
Correct answer: Two-part mould
Stone carving
Painting with plaster

Q5.
Why might an artist use a two-part mould?

Correct answer: To create a replica of an entire object, including complex 3D shapes
To make a flat surface decoration
To carve stone more easily
To speed up plaster setting time

Q6.
When mixing plaster, what should you do to avoid air bubbles?

Mix as fast as possible
Correct answer: Sprinkle plaster into water slowly and tap the container
Add extra water at the end
Use hot water instead of cold

Additional material

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