Jesmonite Retarder is a liquid additive specifically designed to extend the working time of Jesmonite resins. It is added directly to the liquid component before mixing, allowing greater flexibility in complex applications, large pieces or high-temperature conditions.
Technical specifications
| Parameter |
Value |
| Product type |
Cure retarder additive |
| Compatible with |
Jesmonite resins (AC100, AC730 and compatible range) |
| Usage dose |
2 g – 8 g per kg of total mix |
| Addition point |
To the liquid component, before mixing with the powder |
| Presentation |
Liquid |
What it is used for
Jesmonite Retarder is intended for situations where the standard working time of the resin is insufficient. It is especially useful in projects that require elaborate laminates, large-volume castings or environmental conditions that accelerate setting.
- Extending working time in multi-layer laminates with Jesmonite AC100
- Working with Jesmonite AC730 on textured or large-format surfaces
- Castings in warm environments where temperature accelerates setting
- Large-volume mixes that require more handling and pouring time
- Artistic or decorative applications where precision in the finish demands greater room for manoeuvre
- Pieces with complex geometry that need additional time for the material to settle correctly
How to use it
- Weigh the amount of Jesmonite resin you are going to prepare (liquid component + powder).
- Calculate the retarder dose: between 2 g and 8 g per kg of total mix. Always start with the minimum dose.
- Add the Jesmonite Retarder to the liquid component before incorporating the powder.
- Mix the liquid with the retarder for a few seconds to ensure even distribution.
- Incorporate the powder component and mix according to the instructions of the corresponding Jesmonite system.
- Apply or pour the mix with the extended working time. Bear in mind that the demoulding time will also increase proportionally.
Usage tips
Always carry out a preliminary test
The optimal dose is not fixed: it depends on the ambient temperature, the volume of the mix and the Jesmonite system used. Before working on a final piece, run a small test with the minimum dose (2 g/kg) and adjust according to the working time you need. Exceeding the dose can compromise the final cure of the piece.
Temperature and volume, key factors
The higher the ambient temperature or the larger the mix volume, the faster the resin sets. In summer or in warm workshops, it is common to need higher doses within the recommended range. Conversely, in cool environments, the minimum dose is usually sufficient. Always work within a temperature range of 18 °C to 25 °C where possible.
Compatibility and storage
Jesmonite Retarder is exclusive to the Jesmonite range. Do not use it with other acrylic systems without verifying compatibility — for the Acrystal range there is the Retardante Acrystal, specific to that system. Store the product tightly closed, away from heat and protected from direct light to maintain its effectiveness over time.
Frequently asked questions
How much retarder should I add to my mix?
The recommended dose for Jesmonite Retarder is between 2 g and 8 g per kg of total mix. The sensible approach is to start with the minimum dose and run a small test before applying it to a final piece. The workshop temperature and the volume of the mix directly influence the result.
When should I add the retarder — before or after mixing?
Always before. Jesmonite Retarder is incorporated into the liquid component before adding the powder. This guarantees uniform distribution throughout the mix and achieves the retarding effect evenly.
Does the retarder affect the final properties of the piece?
Used within the recommended range (2–8 g/kg), Jesmonite Retarder does not significantly compromise the mechanical properties or the finish of the piece. If the recommended dose is exceeded, the cure may be affected. Always respect the indicated quantities and carry out preliminary tests.
How much does demoulding time increase when using a retarder?
Demoulding time also increases proportionally with the use of the retarder. There is no fixed value: it depends on the dose used, the temperature and the Jesmonite system employed. After your preliminary tests, you will have a reference figure for your specific working situation.
Can this retarder be used with other acrylic systems?
Jesmonite Retarder is formulated specifically for the Jesmonite range. If you work with the Acrystal system, use the Retardante Acrystal, which is the specific additive for that system. Interchanging additives between systems without verifying compatibility is not recommended.
Do I need a release agent when using Jesmonite resins with a retarder?
Using a retarder does not eliminate the need for a release agent. If you work with non-porous or rigid moulds, apply a suitable release agent such as APM WAX Cera Desmoldeante before pouring the mix, regardless of whether you are using a retarder or not.
How does temperature affect the working time of the resin?
The higher the ambient temperature, the faster Jesmonite resin sets. In hot conditions, you may need to use Jesmonite Retarder at the upper end of the range (up to 8 g/kg) to achieve the working time you need. In cool environments, the minimum dose is usually sufficient. Ideally work between 18 °C and 25 °C.
Can I add pigments or fillers together with the retarder?
Yes. Jesmonite Retarder is compatible with pigments and common fillers in the Jesmonite system. Add the retarder to the liquid first, mix briefly, then incorporate the pigments or other additives before adding the powder component. If you use a thixotropic agent, always verify compatibility with the specific system you are using.
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