Making a mold is a complex proposition that involves various factors right from the technique to the choice of material. Indeed, the material used to make the mold – be it clay, plaster, alginate, resin, latex rubber, silicone rubber, polyurethane rubber, etc. - will have a bearing on everything related to the quality, resilience, durability and even the very usability of the mold.
While different mold makers have their own specific criteria for choosing a mold material, there are some basic aspects that have to be kept in mind, such as:
- Consider the material of the model. In general, it is better to pick a material that can be used on stone, wood, glass, metal, wax, plaster, ceramic or clay. In case of a body mold, the material should be safe for using on the skin, capture fine details and cure quickly too.
- Take the characteristics of the model into consideration. Is the pattern simple with no undercuts or does it have a complex shape with deep undercuts? In case of a vertical surface or large/immovable objects, the model making material should be such that it can be applied on the details where it is without running off or needing to be thickened.
- Compatibility with the casting material also has to be taken into account. Certain mold making materials may not be suitable for casting specific types of resins, rubbers or metals.
- There are other aspects that warrant a closer look before closing in on an option – like catalyst, curing agent, working time and cure time at room temperature, etc. While at it, consider if the pot time and demolding time can be modified if needed.
- Focus on the specific performance objectives expected from the mold/mold making material in terms of viscosity, appearance, durability, resilience, shore hardness, tensile strength, flexibility, shrinkage, tear strength, reusability and more.
- In case of a flexible mold, a reinforcing shell mold will be required and the material compatibility factors will come into play again.
- Consider the tools and equipment requirements of particular materials to ensure that the studio is prepped to work as required.
- Take the mold features into account. For instance, a silicone mold varies in many aspects to a resin mold which will again be miles apart from a clay one.
Generally speaking, look for materials that are easy to use, can reproduce intricate details and are known to hold severe undercuts. It will be better if they also feature excellent release characteristics with customizable working times and cure rates. They should be flexible enough to tolerate the stress of demolding and be able to adapt to a range of service temperatures. Good resistance to chemicals and ability to withstand wear and tear with repeated use will also be helpful.