Lesson video

Hi, I'm Miss Blue, and I'm really excited to be learning with you today.

I hope you find our lesson as interesting as I do.

Let's get started.

The outcome of this lesson is: I can experiment with three plaster casting methods and show how form, surface, and construction interact.

Your outcomes might make something like these examples in the pictures below.

Let's have a look at our key words.

Mold: a hollow form used to shape plaster.

Release agent: prevents plaster sticking to the model.

Casting: pouring a liquid material like plaster into a mold where it hardens into the shape of the mold to create a replica.

Let's start with direct pour and shell casting.

What do these two things have in common? Think about how the main shapes might have been formed.

Pause the video here while you have a think.

Let's see what Jun has to say: "They're both 3D objects.

One is a jelly made in a mold." Laura says, "The sculpture has been cast in bronze, a type of metal.

This has also used a mold to create it." What is plaster casting? Well, plaster casting is a process where liquid plaster is poured or applied around an object to capture its shape, texture, and detail.

Once it sets, the plaster forms a mold or cast that can be used to make replicas or explore different surfaces.

Plaster is popular because it sets quickly, is affordable, and can be layered, carved, or combined with other materials.

Let's test your knowledge.

Choose the correct statement.

Is it A: Plaster casting is painting patterns onto clay surfaces? B: Plaster casting is pouring or brushing plaster around an object to capture its shape? Or C: Plaster casting is carving shapes directly into stone? Pause the video while you work out the correct answer.

If you said B, you would be correct.

Plaster casting is pouring or brushing plaster around an object to capture its shape.

Artists using plaster casting as part of their work include: Rachel Whiteread uses plaster and resin casts to capture the negative spaces of domestic environments, such as rooms, stairs and furniture.

Teresa Margolles' "A Thousand Times in an Instant" used plaster casting to preserve objects linked to trans women in Mexico, highlighting fragility, loss, and visibility of transgender lives.

Thomas J.

Price employs casting processes in bronze and other materials to produce powerful figurative sculptures that explore identity, scale, and representation.

In "A Carnival of Overlapping Histories," Ashanti Harris uses plaster casting of faces and hands to explore identity and shared histories.

Plaster casting is an ancient sculptural process.

There are three main types of plaster casting to explore.

Direct pour: where plaster is poured on top of a model coated with a release agent to form a mold.

This mold can then be the final piece or used to make copies of the original model.

Two-part mold: the model this time is cast in two halves with plaster layers to capture more complex shapes.

Shell casting: plaster is brushed or poured in a thin layer over an object to build up a solid shell.

Don't forget health and safety.

Plaster must be worked with responsibly.

When working with plaster, you should: Always wear gloves and an apron.

This stops the plaster drying out on your skin or clothes.

Never wash plaster down the sink.

It hardens in the pipes and can block or damage them.

Work in a well-ventilated space; plaster dust can be harmful if you breathe in too much of it.

Clean tools in a bucket, not under the tap.

Plaster can block drains.

In a bucket, it can set and be disposed of safely.

Let's have a look at how plaster works.

Plaster is usually made from powdered gypsum mixed with water.

Gypsum is a soft, natural mineral made of calcium sulfate.

When mixed with water, the powder forms a thick paste that slowly hardens.

As it hardens, it gives off heat and feels warm.

This is called an exothermic reaction.

Plaster sets quickly, usually within 10 to 15 minutes for small amounts, but full strength can take longer.

Once set, plaster is slightly porous, which means it can be sanded, painted, or combined with other materials.

Plaster captures fine textures, which is why it is perfect for casting and picking up surface detail.

Let's decide if this statement is true or false: Plaster must never go down the sink because it hardens and blocks the pipes.

Pause the video while you decide if this is true or false.

If you said true, you would be correct.

Why? Because plaster sets solid when it contacts water inside drains.

This can cause blockages, damage facilities, and create hazards.

When casting or creating molds, the objects need to be coated in a release agent.

This prevents the plaster from permanently sticking to the object.

There are a number of options to use as a release agent: vegetable oil or baby oil, soft soap, cling film, and petroleum jelly.

It's important to make sure it is applied evenly and covers all surfaces.

Make sure that any excess release agent is removed so that it does not change the surface texture.

Undercuts in a model are areas where the shape curves back on itself, which can trap plaster and make it hard to remove the cast without breaking it.

When making a cast, check the model for undercuts.

Use a two-part mold or add a release agent to tricky areas so the cast can come out cleanly without breaking.

Can you see where the undercuts are in this rubber duck? Clay or plasticine can be used to fill any small holes or undercuts and make the cast removal easier.

Mixing plaster.

You'll need to measure the correct ratio of plaster to water by checking the packet instructions.

Prepare the materials in advance including: clean water, plaster powder, a clean mixing container, a mixing stick or spatula, a yogurt pot or cup to use for measuring, and protective equipment.

Mixing plaster can look like this.

You can see how it starts off lumpy and slowly comes together.

Slowly sprinkle the plaster into water, allowing it to soak naturally.

Mix gently to avoid air bubbles.

It should be the consistency of thick cream or pancake batter.

Tap the tub to remove any air bubbles.

Remember to use the plaster immediately.

Plaster sets quickly, so be ready to use it straight away.

Casting using a direct pour technique.

Coat the model or object to be cast with a release agent.

Place the object into a container.

Pour plaster slowly, tapping the sides of the container to release any air bubbles.

Here's an alternative method for the direct pour technique.

Roll a slab of clay and create a wall of clay around the edge to contain the plaster.

Push the object onto the clay to create an impression.

Remove the objects.

Pour plaster slowly, tap to release any bubbles, and allow to set.

Once fully cured, the mold can be turned over and the clay and other objects can be removed.

The mold can be used to create objects to use in your own artwork.

This method is useful when creating multiples.

The hollow space creates a negative mold which can be filled to make a replica of the object.

Plaster or clay can be used to create the new piece.

Lucas is reflecting on the direct pour technique of casting.

He says, "The cast of the building block has worked well.

It needed a small amount of release agent because it was a shiny, smooth surface.

It reminds me of a work by Rachel Whiteread capturing the negative space left by the block." Casting using a shell brushing technique.

Choose a textured object and apply release agent evenly.

Brush thin layers of plaster over the object.

Build up three to four layers to form a shell.

Once set, you can carefully peel away the object.

When removing the object, take care as the shell mold can be fragile.

Extra layers of plaster can make it stronger.

Here's a task for you on creating a plaster cast.

These two tasks can be completed alongside each other.

Whilst one is setting, the second can be completed.

First, cast one small object using the direct pour technique.

Then, cast a textured object using the brush shell technique.

Record the steps in your sketchbook with drawings, photographs, and annotations.

You should create a negative mold.

Use small objects like a chess piece, seed pod, shell, toy, or a model that has been created.

Make sure there are no undercuts.

Coat small objects in a release agent.

Place objects inside a container.

Mix plaster to the correct ratio.

Slowly pour plaster over the object.

Tap gently to release any air bubbles.

Pause the video while you work on this task.

For the second part of the task, you are using a brushed shell technique.

Focus on the texture of the object and build up thin layers.

Use an object that has a good, strong textural detail.

Remember to coat the object in a release agent.

Mix the plaster to the correct ratio.

Brush thin layers of plaster.

Repeat three to four times, allowing partial settings in between.

Peel away to reveal the shell form and captured texture.

Pause the video while you work on the second part of the task.

You may have cast an object that looked something like this.

You can see this person has used a variety of found things like keys, natural forms, and Lego.

Your work may have included simple objects, varied textures, or different depths of impression.

Using the brush shell technique, you may have cast an object that looked something like this.

This person has used a feather to create an impression.

Your work may have included different textures, unexpected details, or sharp angles.

Now let's have a look at two-part molds.

So why do artists use casting techniques? To record and preserve, to capture fragile objects like plants, leaves, and shells.

To transform and reimagine, turning ordinary items into art.

To change scale and create impact, small objects into large sculptures.

To preserve identity and memory, casting body parts, personal items, or spaces.

What aspects of casting interest you and why? Pause the video here while you come up with some ideas.

Casting can be a starting point for an artist, not just an end result.

Artists will think about what they want to say with their cast elements or how they want to use them in their work.

Artists might explore: contrasting textures like rough versus smooth, combining casts with other materials like wood, fabric, cardboard, etc.

, repeating or arranging casts into patterns.

How might you use the casting techniques in your work? Pause the video here while you have a think.

Artists using plaster casting in a creative way in their work include: Bharti Kher, who often uses plaster casts of the human body in her sculptures, exploring memory, identity, and the traces left by physical presence.

Rachel Dein uses plaster relief casting to capture delicate detail from plants, flowers, and everyday objects, preserving their textures as permanent records.

Mark Quinn uses casting techniques, often in plaster before using other materials, to explore the human body, identity, and themes of transformation.

Here are some other examples.

Alberto Giacometti and Lynn Chadwick both relied on plaster as a vital stage in their sculptural processes.

Giacometti used it to build and rework delicate human figures, while Chadwick shaped plaster into bold, angular forms. In both cases, plaster casting acted as a bridge between experimentation and finished metal sculptures.

Sydney Kumalo uses plaster and clay to model human and animal forms before casting in bronze, blending African traditions with modern sculpture.

Let's decide if this statement is true or false: Casting can only be used to make exact copies of objects.

Pause the video while you decide.

If you said false, you would be correct.

Why? Because casting can transform objects, be combined with other materials, or used in patterns and installations, not just replications.

Why might an artist create a two-part mold? Pause the video here while you come up with a response.

Well, two-part molds allow an artist to create a replica of an entire object and not just one side.

Two-part molds allow the more complex 3D shapes to be captured.

Creating a cast using a two-part mold technique.

Choose an object and check for undercuts.

Coat with a release agent.

This person is using petroleum jelly.

Place the object half-deep into clay or plasticine so that only half is showing.

Build a clay wall around the object or use a container.

This will contain the plaster.

Create three or four rounded indents.

These will allow the two halves to interlock.

Prepare and pour the plaster into the mold.

Tap it to remove air bubbles and let it set.

Remove the clay or clay walls.

Turn the mold over and remove the clay.

Add the release agent to the surface of the mold and exposed object.

Build a clay wall around the object or use the container again.

Pour fresh plaster over the other side of the object.

Tap to remove any air and allow to set.

Once the mold is cured completely, it can be used to create a replica of the object.

These can then be used in your own artwork.

Here's a cast of a pepper created using a two-part mold.

The hollow space between the two halves can be filled to make a replica of the original object.

Plaster or clay might be used to create the new piece.

Let's test your knowledge.

Choose the correct statement.

A: A two-part mold is made in halves so the object can be released easily.

B: A two-part mold is only used to make flat objects.

Or C: A two-part mold means pouring twice as much plaster to make it stronger.

Pause the video while you decide on the correct answer.

If you said A, you would be correct.

Splitting the mold into two halves allows more complex 3D shapes to be captured and removed without breaking the cast or the object.

Your task now is to create your own two-part mold.

Select an object to create a two-part mold and check for undercuts.

Think about where the halfway point is on the object, like a toy, fruit, or shell.

Place the object in clay up to the halfway point.

Build a clay wall around the object.

Create indents to lock the two halves together.

Coat the object with a release agent.

Pour plaster in the first half and let it set.

Turn and remove the clay.

Apply release agent.

Build a clay wall for the second half.

Pour the second half and allow to set.

Remove the clay and object.

Separate the two halves and allow them to cure completely.

Pause the video here while you work on this task.

Your response may have looked something like Izzy's.

She says, "I am really pleased with my two-part mold.

The duck shape has come out really well and created an interesting shape to make a copy from.

I can imagine using this as a basis for a set of ducks, exploring the idea of identity." Lucas says, "The shell was a bit tricky to cast.

I had to fill the hole with clay and make sure the release agent was applied in a thin layer so the texture was captured.

It worked, and then I've got a really detailed mold." Part two of your task is to reflect on your work.

Think about the following questions to help you reflect: Which method was the easiest? Which gave the best surface detail? Which would you improve on next time? What did you learn about plaster as an object? How were you influenced by the artists you researched? Pause the video here while you work on the task.

Alex says, "I found the direct pour method easiest.

My shell casting was difficult.

The cling film kept moving and I didn't pick up the texture of the feather very well, but it did create some unexpected textures that were not what I had planned but are really interesting." Izzy says, "I found the two-part mold making really interesting.

I wasn't sure how it was going to work out, but it went well.

The plaster was quite tricky to work with, and when I was making the shell cast, it first of all was running off.

Then suddenly it started to set and I had to get the layers on quite quickly, but it worked really well in the end." To summarize, plaster is a versatile material that sets quickly and records fine detail.

Direct pouring creates a simple cast of a model's surface.

Two-part molds make it possible to cast complex or rounded forms. Layering plaster builds strength and allows a shell to be created.

A mold is the hollow form left behind once the model is removed.

A release agent makes it easier to separate plaster from the model.

Exothermic reactions explain why plaster feels warm as it sets.

Casting can preserve shapes, textures, and objects for study or reuse.

Plaster can be finished, painted, or combined with other materials.

Different casting methods give different possibilities in 3D design.

Thank you so much for listening and paying attention in this video lesson.

See you next time.