Jesmonite is an essential material for creating moderndecorative items, candle holders, trinket trays, serving trays and even personalised accessories. Easy to work with, quick to set and offering a neat finish, it allows you to create a wide variety of pieces, whether you’re a beginner or a more experienced creator.
Before embarking on a specific project, it’s important to master the basics. In this guide, you’ll discover all the essential steps for using Jesmonite effectively: calculating quantities, preparing the mould, mixing, pouring, demoulding, as well as best practices to ensure a clean and durable result.
These steps form the basis for many Jesmonite creations. You can then apply them to various more specific tutorials.
Why learn the basics of Jesmonite?
Whatever creation you wish to make, certain steps always remain the same. Measuring quantities accurately, maintaining the correct proportions, avoiding air bubbles and allowing your creation to dry sufficiently are all essential steps for achieving a high-quality result.
This guide will therefore help you understand the general method to follow before moving on to more detailed projects. Once you’ve mastered these basics, you’ll be able to easily adapt the technique to suit your chosen mould, shape or project.
Essential equipment for working with Jesmonite
For this example, we have chosen to use the AC100 range, which is the most popular and easiest to work with.
Raw materials
- Jesmonite Duoset AC100
- Water
Equipment
- Beaker
- Precision balance
- Silicone mould of your choice
- A container for mixing
- A spoon or spatula that is thick enough
- A vibrating plate is recommended
The essential steps for successful Jesmonite creations
1. Measure the capacity of your mould
Before preparing your Jesmonite, start bydetermining exactly how much material you’ll need to fill your mould.
Place your empty mould on a precision scale, then press the tare function so that its weight is not taken into account. Next, pour water into the mould up to the desired level.
The weight displayed on the scales gives you an accurate indication of your mould’s capacity. You will then use this figure to calculate the quantities of Jesmonite required for your creation.
2. Dry your mould thoroughly
Once you have taken the measurement, empty out all the water and then dry your mould thoroughly.
This step is important because traces of moisture can affect the final result. In particular, they can cause marks or whitish streaks to appear on your creation.
3. Calculate the quantities of Jesmonite
Once you know the capacity of your mould, go to our Jesmonite calculator and enter the value you’ve obtained. The calculator will help you determine the quantities of powder and liquid needed to fill your mould using the correct proportions.
On our online calculator, you have the option to add a 10% safety margin. We recommend applying this to account for any small losses of material that may remain in the container or on the spoon during mixing, and to ensure you have enough Jesmonite to completely fill your mould
4. Weigh the components separately
Place your beaker on the scales and tare the scales before weighing out the required amount of liquid. Then do the same for the powder, using a container large enough to allow for easy mixing later on.
Once both components have been weighed, get ready to mix them. Jesmonite starts to set relatively quickly, so it’s advisable to have all your equipment ready before you begin.
5. Mix until smooth
Gradually pour the powder into the liquid whilst stirring continuously. You can do this in the same way as when making pancake batter to gradually incorporate the powder and minimise the formation of lumps.
Use circular movements whilst regularly scraping the bottom and sides of the container. The aim is to achieve a smooth mixture with no powder left in clumps.
It is best to use a spatula or a spoon that is thick enough to mix the mixture. We do not recommend using a whisk. This may incorporate more air into the mixture and increase the number of bubbles in your creation.
Room temperature can also affect the working time. The warmer it is, the faster the Jesmonite may set. If you wish to have more time to work with your mixture, you can use a suitable Jesmonite retarder.
6. Pour the Jesmonite into your mould
Once your mixture is smooth, pour it gradually into your silicone mould. Carry out this step evenly to ensure all areas of the mould are filled properly.
7. Minimising air bubbles
Air bubbles are one of the main challenges encountered when creating objects from Jesmonite. To minimise them, ideally place your mould on a vibrating plate after pouring. The vibrations allow any air bubbles trapped in the material to rise to the surface.
If you do not have a vibrating plate, you can gently tap the sides and underside of the mould with your fingers. This method can help bring some of the bubbles to the surface, but it will be less effective than a vibrating plate.
8. Allow sufficient setting time
Once your mould is filled, leave the Jesmonite to set without moving your creation. The time required before demoulding depends, in particular, on the range used.
AC100: approximately 20 to 30 minutes
AC84: approximately 2 hours
AC740: approximately 4 hours
The temperature of your surroundings can affect the setting time. In a warm environment, Jesmonite may set more quickly. Conversely, in a cooler room, it may take longer before it is hard enough to be removed from the mould.
9. Removing your creation from the mould
Once the setting time has elapsed, carefully remove your creation from the mould. Even if it already feels solid, the curing process is not yet complete.
10. Leave the Jesmonite to cure for 24 hours
After removing it from the mould, we recommend waiting around 24 hours before using or protecting your creation.
During this time, the Jesmonite continues to lose moisture and harden gradually. Allowing it to set for this period ensures a more stable and durable creation before moving on to the finishing stages.
11. Protect your creation if necessary
Depending on the intended use, you can then apply a suitable protective treatment: Jesmonite acrylic gloss. This step is essential if your creation is intended to hold wax.
After applying the protective coating, allow your creation to dry again for around 24 hours before pouring wax into it or using it.
Summary of common mistakes to avoid when preparing Jesmonite
To achieve a clean finish, there are certain mistakes you should avoid right from your very first projects.
- Do not leave any traces of water in your mould before pouring.
- Do not prepare your mixture until you have all your equipment to hand.
- Do not remove your creation from the mould before the Jesmonite has set sufficiently.
- Do not pour wax immediately after removing the piece from the mould. Allow your creation time to harden and apply a suitable protective coating where necessary.
Does temperature affect how Jesmonite sets?
Yes, ambient temperature plays an important role in the working time and curing of Jesmonite.
Warm environment: your mixture may start to set more quickly. It is therefore important to prepare all your materials in advance and to work in an organised manner.
Colder environment: Jesmonite may, on the other hand, take longer to set completely.
Key points to remember
Mastering Jesmonite relies above all on a few good habits: calculating quantities correctly, preparing your equipment before you start, achieving a smooth mixture, minimising air bubbles, and adhering to setting and drying times.
Once you’ve mastered these basics, you’ll be able to apply them easily to a wide range of projects and experiment with new shapes, finishes and combinations. Use this guide as a reference before starting any of your creations.
To take your skills further and ensure you’re properly equipped right from the start, check out our guide listing all the essential accessories you’ll need to get started with Jesmonite.
