Avoid wasting time and money on molds that don't work
Many jewelers have been through this: they invest in a beautiful project, approve the design, order the mold — and when it comes time to produce, the pieces come out with flaws, lose details, or the mold wears out prematurely. The cause is almost always a lack of technical knowledge regarding the right material for each situation.
In this guide, MS Soluções para Joalheria — with over 30 years of experience in technical jewelry production — explains everything you need to know about vulcanized rubber molds: what they are, how they work, when to use them, and how to ensure maximum durability and reproducibility.
What is a vulcanized rubber mold?
A vulcanized rubber mold — also known as a rubber mold or vulcanized silicone mold — is a production tool that allows for the reproduction of an identical piece of jewelry dozens, hundreds, or thousands of times with high fidelity to the original model.
The vulcanization process consists of compressing raw rubber around the metal model (called a master or cliché) using controlled heat and pressure — typically between 150°C and 180°C for 10 to 30 minutes, depending on the thickness. The result is an elastic, flexible, and resistant mold that retains every detail of the original piece.
What it is used for: practical applications in jewelry production
The vulcanized mold is the heart of serial jewelry production. It allows for: wax injection for subsequent casting via the lost-wax method; production of multiple identical pieces from a single master; design storage for years without the need for modeling rework; and amortization of project costs diluted over hundreds of units.
Types of rubber: which one to choose?
Traditional vulcanized rubber (caucho): higher durability, supports more injection cycles (800 to 2,000 injections depending on the design), ideal for continuous production pieces. Requires high vulcanization temperature — incompatible with resin-based masters or those printed in heat-sensitive materials.
Room temperature silicone (RTV): cold vulcanization, compatible with wax, resin, or any material masters. Lower durability (typically 300 to 600 injections), but ideal for projects with very complex geometries, deep undercuts, or experimental designs.
High-temperature silicone: a hybrid that combines durability close to traditional rubber with the compatibility of RTV silicone. A more balanced professional option for most modern jewelry applications.
How to make it: the step-by-step process
1. Master preparation: the original model must have an adequate wall thickness (minimum 0.8mm), an absence of uncalculated undercuts, and proper surface finishing — as the mold will faithfully reproduce every imperfection.
2. Assembly of the pack: the master is positioned in the center of the raw rubber sheets, with injection channels strategically placed to ensure uniform wax filling.
3. Vulcanization: the pack is placed in the vulcanizing press with temperature and time controlled according to the rubber manufacturer's specifications.
4. Mold cutting: once vulcanized, the mold is cut manually by an experienced professional — this is the most critical step. A good cut ensures a perfect seal, without burrs and with easy demolding. A poor cut ruins a perfect mold.
5. Injection test: the first injections validate filling, demolding quality, and fidelity to the original model.
Durability: what affects the mold's lifespan
A well-made and well-maintained mold can last for years. The main factors that reduce durability are: excessive wax injection temperature (above 70°C progressively degrades the silicone); use of excessive mold release agent (clogs pores and harms piece finishing); improper storage (sunlight, heat, or solvents degrade the rubber); and forced demolding (tears in undercut areas).
Perfect cuts: the differentiator that separates the professional from the amateur
Mold cutting is a technical art. A well-cut mold: closes without visible misalignment on injected pieces; has cut lines that naturally follow the design's relief; facilitates demolding without distorting the wax; and maximizes the number of cavities per mold to increase production per cycle.
At MS Soluções para Joalheria, all molds are cut by professionals with over a decade of experience in this specific step — because we know that a good cut can be worth more than the mold itself.
When is it worth investing in a vulcanized mold?
The vulcanized mold pays for itself when you intend to produce the same piece more than 15 to 20 times. Below that, direct casting via 3D printing may be more economical. Above that, the mold drastically reduces unit cost and ensures quality consistency that standalone 3D printing cannot achieve at scale.
Rule of thumb: if you have a bestseller or a piece with regular demand — make the mold. You will recover your investment within the first few production runs.
Conclusion: right mold, right production
The vulcanized rubber mold is the foundation of well-executed serial jewelry. With the right material, the correct process, and a professional cut, you have a tool that works for you for years — producing identical pieces with consistent quality and an increasingly lower unit cost.
MS Soluções para Joalheria offers a complete vulcanized mold-making service: from technical design analysis to vulcanization, professional cutting, and injection testing. Get in touch and request your quote.
Did you like this topic? See also: How 3D printing for jewelry works and when to use STL | Direct casting with castable resin: complete guide
Want to master the entire process from 3D design to final jewelry? Check out our Complete Course on Professional Casting and Molding.
Need vulcanized mold-making services and 3D projects? Check out our high-quality jewelry solutions or follow us on Instagram @ms.solucoesparajoalheria.
