Plaster of Paris Signature 1kg

Mont Marte Plaster of Paris Signature 1 kg — the NZ go-to plaster for school projects, hobby casting, sculpting and mould-making. $7.99 a bag, in stock at our Morningside Auckland warehouse, free NZ shipping over $75.

What you get

• 1 kg of Mont Marte Signature plaster of paris powder
• Mixes 1 part water to 2 parts plaster by volume (rough rule of thumb — varies with weather)
• Sets in 10–15 minutes, fully cured at 24 hours
• Smooth, even light-grey set that takes paint and finish well

What it's good for

• School projects — volcanoes, dioramas, NCEA Level 1–2 art folio work
• Casting and moulding — pour into silicone or rigid moulds, pop out a hard piece
• Sculpting — build up over a wire armature for figurative work
• Kids' craft — handprints, fridge magnets, painted ornaments

How to mix plaster of paris (the right way)

1. Always add plaster to water, not water to plaster. Pour water into your mixing tray first.
2. Sprinkle the plaster onto the water surface in small batches — don't dump it in.
3. Gently stir with a spatula until smooth and uniform light grey.
4. Tap the tray to release air bubbles.
5. Pour into mould or build-up immediately — you have about 5–10 minutes of working time.
6. Don't mix with bare hands — use a spatula or stick.

Tips for a better set

• Warm water = faster set; cool water = more working time.
• For a stronger cast, add a tablespoon of PVA glue per cup of water to the mix.
• For smoother surface, vibrate the mould gently for 30 seconds after pouring.
• Don't rush the cure — minimum 24 hours before painting or sanding.

Pairs well with

Most of our plaster of paris buyers also pick up Mont Marte acrylic paint for finishing, detail brushes for painting, and modelling tools for shaping wet plaster.

Frequently asked questions

How long does plaster of paris take to set?

Initial set in 10–15 minutes (no longer soft). Hard enough to demould in 1–2 hours. Fully cured and paint-ready at 24 hours. Don't rush the final cure — freshly-set plaster contains moisture that will damage paint adhesion.

Can you use plaster of paris with kids?

Yes — it's safe for children's craft when an adult handles the mixing. The exothermic reaction warms the mould as it sets — safe but a fun talking point for school projects.

What's the right water-to-plaster ratio?

1 part water to 2 parts plaster by volume is the standard. For thicker, harder pours use less water; for thin pours use slightly more. Add plaster to water (not the other way around).

Can you paint plaster of paris?

Yes, once fully cured at 24 hours. Acrylic, watercolour and poster paints all work well. For best adhesion, seal the surface first with a coat of diluted PVA or acrylic medium, then paint.

How do you store leftover plaster powder?

Keep the bag sealed in a dry place. Plaster absorbs moisture from the air, which makes it set faster (or not at all if it's been wet). Stored properly, the unopened bag lasts 1–2 years.

Do you ship plaster of paris NZ-wide?

Yes, we ship NZ-wide from our Morningside Auckland warehouse. Tracked courier 1–3 business days to main centres, +1–2 days rural. Free shipping over $75 NZD.