How To

How to Cast like Rachel Whiteread

Ever wondered how casting works? Find out how with our step-by-step

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A bit of background

I simply found a wardrobe ... I stripped the interior ... turned it on its back, drilled some holes in the doors and filled it with plaster until it overflowed.

Rachel Whiteread

Rachel Whiteread uses industrial materials such as plaster, concrete, resin, rubber and metal to cast everyday objects and architectural space. Her works capture negative spaces and use familiar materials and objects in unexpected ways.

Rachel Whiteread, ‘Untitled (Twenty-Four Switches)’ 1998
Rachel Whiteread
Untitled (Twenty-Four Switches) 1998
Tate
© Rachel Whiteread
Rachel Whiteread, ‘Untitled (Stairs)’ 2001
Rachel Whiteread
Untitled (Stairs) 2001
Tate
© Rachel Whiteread

Cast like Rachel Whiteread

You can cast just about anything. For this how to, inspired by Rachel Whiteread’s use of domestic objects, we cast a light bulb. Watch the film to learn about making and casting with a two-part mould. If the film leaves you feeling really inspired, follow our step-by-step below and have a go yourself.

Things you'll need

  • Clay

  • Plaster and water

  • Jesmonite and catalyst

  • Jesmonite pigment (optional)

  • Silicone and catalyst

  • Release agent

  • Clamps

  • Tools: scraper, rolling pin, clay tool, knife

  • Sandpaper

  • Snacks and a good book!

  • Object to cast

  • Bowls for mixing

  • Plastic sheeting

  • Tissue

Step 1: Choose your object

A lightbulb

Decide what you want to cast. For this method, we recommend choosing something not much bigger than your hands. If you’re trying casting for the first time, choosing something with a flat side will help.

Step 2. Make a clay bed

A lightbulb in a clay bed

Lay your object flat on a surface. This surface will end up covered in clay and plaster dust so choose somewhere you don’t mind getting messy!

Put some clay underneath your object to secure it. Create a smooth and even bed of clay extending to 10cm around the object. The clay should reach half way up the object. This exposed top half of your object will become the first half of the mould.

Step 3: Block out a pouring hole, make a channel

Clay stopper at base of lightbulb

Add a small piece of clay to your object at one end. If your object has a flat or thin end, choose that end! This will create the tunnel in the mould to pour in when it comes to the casting bit.

Using a clay tool, create a channel around the object. This will help the two halves of the silicone mould fit together.

Step 4: Build some walls

Building a clay wall

Roll clay out to 2cm thick. Cut into strips that are 10cm wide*. Attach these strips to the clay bed approx. 3cm away from the edge of the object, shaping the strips around the object. You have now created the container for pouring the silicone!

*these may need to be wider if your object is taller than our light bulb. To be safe, the wall needs to clear the top of the your object in the clay bed by 5cm.

Step 5: Mix and pour the silicone

Pouring silicone

First of all, grease the visible surface of your object in the clay bed. We used release agent but you could use petroleum jelly or cooking oil. This creates a barrier between the object and silicone so nothing gets stuck.

Following the instructions on the packaging, mix the silicone liquid and catalyst. Once it’s mixed, you have to act fast! Pour the silicone mixture over the object. Make sure there is between 0.5-1cm silicone covering the highest exposed part of the object.

Cover the entire thing in plastic sheeting to stop the clay drying out while the silicone dries.

Take a break

Wait for the silicone to dry. The amount of time will depend on your catalyst. They range from slow to very fast drying! It will be springy and solid to the touch when ready.

Step 6: Build some more walls

Clay walls for plaster

Peel the clay walls for the silicone off. Rebuild a new clay wall, same thickness and height, 3-4cm away from the edge of the set silicone. You have now created the container for the plaster.

Step 7: Make registration marks

Registration marks

Make some registration marks in the clay. Think of these as little craters. They will become like jigsaw pieces when you slot both parts of the mould together. We used a clay tool but you could use a spoon or a knife.

Step 8: Mix and pour the plaster

Pouring plaster

Mix plaster and water according to the ratios on the packet. You will need roughly the same volume of each. Add plaster powder to water until the plaster settles on the top. Mix until it is the consistency of double cream. Pour the plaster over the set silicone to the top of the walls.

Take another break

Take another break whilst you wait for the plaster to dry. The plaster will heat up as it dries. Don't panic, this is totally fine! It is caused by the exothermic reaction that happens as the plaster sets.

Step 9: Take down the walls, flip and clean

Cleaning the clay off

Take down the clay walls to reveal the plaster jacket and turn whole thing over. Remove all of the clay from the plaster, silicone and your object. This can be fiddly so you may want to use a tool you can scrape with. Then give your object a good clean.

Step 10: Fill the hole for the pouring tunnel

Fill the pouring hole

This step is very important! Before doing anything, make sure you fill the hole in the silicone at the base of the object with some clay.

Repeat!

Second set of clay walls

Repeat steps 2–9 on the reverse side of the object. The wall building is a easier this time round. You can line them up with the edges of the set plaster and set silicone.

Remember to grease the set silicone and plaster parts before pouring!

Step 12: The first reveal

Opening the mould

Crack open the two halves of the mould. You might need to use a knife for this. Ta da! Here is your two part mould.

Take your object out and give the silicone a clean.

Ready to cast

Finished two part mould

Congratulations on getting this far! You have now created a two part mould that you can use to create casts of your object again and again.

Step 12: Secure the mould

Clamping the mould together

Clamp the two halves of the mould together. You could improvise with two pieces of board and some string, as long as the mould is secured tightly closed.

Step 13: Mix Jesmonite, pour and agitate

Pouring the jesmonite mixture

Mix the Jesmonite powder and catalyst according to the ratios on the packet. We used Jesmonite as it can be made to look like many things! You can add colour or textural elements to change the finish. We chose a few drops of green pigment.

Pour the Jesmonite mix into the mould from the pouring tunnel created with that little piece of clay!

Gently wiggle the clamped mould to make sure the Jesmonite has coated all parts of the mould. This will also help get rid of any air bubbles in the mixture.

Wait for it to set

Wait for the Jesmonite to set, according to the drying times for the product. A hand-sized object should be lightly set in an hour. Leave it to dry overnight for it to set fully.

Step 14: The finishing touches

Opening the mould

Unclamp the mould and crack open the two halves. Here is your cast object! Remove it from the mould. You can slice off the cast tunnel. Use sandpaper to smooth any rough edges, usually at the join of the two halves of the mould.

The finished product

The finished cast lightbulb

There you have it, your very own Whiteread-inspired lightbulb! We'd love to see how yours turn out. Show us at @TateCollectives on Instagram, Twitter, Facebook or Tumblr.

Want to see how Rachel Whiteread has used casting in her art? Her exhibition at Tate Britain celebrates over 25 years of her work. Open 12 September – 21 January 2018.

Book now

Artworks created by casting

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