How to Make Plaster of Paris Christmas Decorations (Easy NZ Guide)

One of our customers, Aimee, sent us a photo last week. She'd cast a tray of Christmas decorations from Plaster of Paris so the kids at her daycare could each paint one and take it home as an end-of-year present. Stars, trees and little shapes, all set and ready for colour.

It's a great idea, and it's easier than it looks. Plaster is cheap, it sets hard in minutes, and once it's dry it takes paint beautifully. Here's how to do it yourself, whether you're making a few for the tree or enough for a whole class.

What you need

• Plaster of Paris. We use Plaster of Paris Signature 1kg ($7.99). One bag casts a lot of small decorations.
• A silicone mould. Christmas chocolate or ice-cube moulds work well. Silicone is best because the pieces pop straight out.
• Acrylic paint. The Signature Acrylic Paint Set 12 x 12ml ($8.99) has all the Christmas colours you need, and the small tubes are easy to share around a table.
• Brushes. A mix of small and fine brushes, like the Gallery Series Acrylic Brush Set 6pc.
• Varnish (optional). A coat of Gloss Acrylic Varnish makes the paint shine and protects it.
• A mixing container you don't mind ruining, a spatula or stick, water, newspaper, and ribbon or twine for hanging.

Step 1: Mix the plaster

1. Pour water into your container first. Use roughly 1 part water to 2 parts plaster by volume.
2. Sprinkle the plaster onto the water a little at a time. Always add plaster to water, not water to plaster.
3. Stir gently with a spatula until it's smooth, like thick pouring cream.
4. Tap the container on the bench to bring air bubbles to the top.

Only mix what you can pour in the next 5 to 10 minutes. Plaster starts to set quickly, so do it in small batches if you're filling lots of moulds.

Step 2: Pour into the mould

1. Pour the plaster into each shape, filling right to the top.
2. Tap or gently jiggle the mould for 30 seconds to release bubbles and get a smooth face.
3. For hanging: once the plaster has thickened but isn't hard (after about 10 minutes), push a straw or skewer through near the top to make a hole. Wiggle it out before the plaster sets fully.

Step 3: Let it set and pop them out

The plaster sets in 10 to 15 minutes and is usually hard enough to come out of the mould after 1 to 2 hours. Bend the silicone back gently and push each piece out from underneath.

Then leave them somewhere dry for a full 24 hours before painting. Freshly set plaster still has water in it, and paint won't stick properly until it's dry. They'll go lighter in colour as they dry out.

Step 4: Paint them

• For brighter colours, brush on a thin base coat of watered-down PVA glue first and let it dry. It stops the plaster soaking up the paint.
• Start with the big areas, let them dry, then add details like dots, stripes and names with a fine brush.
• Finish with a coat of varnish if you want them to shine and last for years.
• Thread ribbon or twine through the hole and they're ready for the tree.

Doing it with a class or daycare group

This is where Aimee's idea really works. The adults do the messy part, and the kids do the fun part.

• Cast ahead. Make all the decorations a few days before, so they're dry and ready on painting day.
• Adults mix and pour. Keep the dry powder away from little faces, as it's dusty.
• Never put fingers or hands into setting plaster. It gets warm as it sets.
• Name them. Write each child's name on the back in pencil before painting.
• Share the paint. Squeeze small dots onto paper plates so each table has every colour.
• Painted decorations make a lovely end-of-year present for families, and they cost very little per child.

Common questions

How long before I can paint plaster decorations?

Wait 24 hours. The pieces need to dry right through or the paint won't stick well.

Why did my decorations crack or crumble?

Usually too much water in the mix. Stick to about 1 part water to 2 parts plaster. For stronger pieces, add a tablespoon of PVA glue per cup of water when you mix.

Can kids do the whole thing?

Older kids can help pour with an adult. For younger kids, cast the decorations ahead and let them do the painting.

What do I do with leftover plaster?

Never pour it down the sink, as it sets in the pipes. Let it harden in the container and throw it in the rubbish. Keep the unused powder sealed in a dry place.

Get started

Grab a bag of Plaster of Paris, a set of acrylic paints and a few brushes, and you're set for a whole tray of decorations. Orders go out from Morningside, Auckland in 1 to 3 working days, with free NZ shipping on orders over $75.

Made some? We'd love to see them. Reply to any of our emails with a photo.