---
title: Mix and pour the plaster
slug: mix-and-pour-the-plaster
step: 4
howto: make-plaster-moulds-for-large-products
tags: ["product","injection","extrusion","mould"]
category: Moulds
difficulty: Medium
time: < 1 week
location: 
---
# Step 4: Mix and pour the plaster
Mix the casting plaster according to the manufacturer's specifications. In this instance, chopped fiberglass (fibreglass) is added to enhance the mold's durability.

Pour the mixture into the box, generally aiming for a depth twice that of the model.

Immediately after pouring, gently tap the box with a hammer for a few minutes to allow any air pockets to rise to the surface.

Let the plaster cure for a couple of days before demolding.
![IMG_3541.jpg](/resources/howtos/make-plaster-moulds-for-large-products/img_3541.jpg)
![IMG_3599.jpg](/resources/howtos/make-plaster-moulds-for-large-products/img_3599.jpg)