Using a Release Agent in Mold Making and Casting

Before making a mold or cast, the model or mold has to be prepped for the job. This includes applying a coat of release agent as this will aid in easy demolding. The same goes for body molds as well.

There are many intricate minutiae involved in making a mold or cast. It is not just about the choice of material or technique; the artist also has to consider various other factors and requirements that can affect everything from the details captured in the mold to the quality of the final cast.

One such detail is the use of a release agent. The name is self-explanatory – a release agent keeps the mold from sticking to the model or the cast from adhering to the mold, thus facilitating easy demolding. Household products like petroleum jelly or paraffin wax can serve well as a release agent, however, for best results, it is advisable to use a professional mold release.

Keep in mind that there are certain materials like silicone rubber that do not stick to anything except itself. Therefore, it is commonly perceived that a release agent is not required. However, it is still better to use one as this will significantly increase mold life!

How to use?

Before applying the release agent, first clean the model or mold properly to prevent any kind of unevenness in the mold or cast later on. The model or mold should be sealed if needed and allowed to become completely dry.

Spray the release agent uniformly but sparingly to cover the entire surface (interior or exterior). Alternatively, the release agent can even be applied with a brush. For best results, hold the can at a constant distance from the surface (12” to 18” is recommended) and ensure that the same pressure is applied. Do not go overboard, as too much release agent may cover the details and lead to irregular distortions. This can also end up causing stains or air bubbles.

Allow the release agent to dry for 10 minutes or so before applying/pouring the mold making or casting material. In case an in-mold paint is to be used, it should be applied after the release agent dries. Once cured, the mold or cast can be easily removed by loosening around the edges.

Where to find?

EnvironMolds is the best resource when it comes to everything to do with how to make molds. It provides two great mold release options –

  • ArtLube100 is a silicone-based release agent specifically formulated for use with polyurethane molding systems and KastEZ urethane casting system. It can also be used with other polyurethanes, epoxies, polyester resins and silicone rubbers.
  • IsoKote 1000 (formerly Synlube 1000) is another silicone-based release agent formulated for the release of both low and high temperature cured urethanes from metal and plastic molds. It can also be used with epoxies.

Then there is MoldEZ Hair and Mold Release, a water soluble release agent that prevents alginate from tangling in the hair when making body molds.


The Art of Life Casting Explained

Getting into the nitty-gritties of life casting will show that it is complicated for sure, but doable with some practice and a lot of care. The artist has to always consider that he/she is working on a live model!

Life casting is a specialized art of making a three dimensional copy of the human form with a high level of realism and detail. Highly skilled molding and casting techniques are used to capture the finest of features of the human body; it can be any part from the face, hands and feet to the torso or the entire body.

Going way beyond a painting or photograph, the sculpture will recreate each and every fingerprint, dimple, fold and other lines on the body to imitate the physical presence and essence of the person. Life casts can be made with or without clothing.

How does it go?

The model is first prepped for what lies ahead. The pose is discussed and practiced while keeping comfort and safety in mind. Petroleum jelly or other release agent is applied first to prevent the body mold from snagging in the body hair.

Alginate, which is safe for the skin, is commonly used to make the body cast. It should be mixed with soft water in the specified ratio to form a creamy mixture of a workable consistency. The hand or foot has to be merely dipped into the alginate container and allowed to set. This works quickly and the body part can be slowly wriggled out to leave a negative mold behind.

A more complicated but proficient method is to apply the alginate on the body. It has to be carefully spread and smoothed into all the contours while taking care of the eyes, nose, ears, hair and so on. The artist has to work quickly as the alginate tends to set quickly. It is then reinforced with plaster bandages; this shell mold will enable the alginate to retain its shape.

The mold can be demolded pretty soon, all it takes is working the fingers under the edges and wriggling the body a bit. It can be corrected if needed and will be ready for casting. Plaster or other casting material is poured into the mold and allowed to cure. Just remove it and finish as desired. Some people even insert a wire or hook in the casting material itself and it can be hung on the wall later.

Keep in mind that the casting should be done quickly too, as the alginate will tend to shrink as it loses water on contact with air. Moreover, these are one-off molds and cannot be used for making multiple copies.

Making a body casting involves complex procedures, but the going gets easy and straightforward with time. The life casting artist has to be particularly careful about the model as it is a live person that he/she is working on here! Last but not the least; life casting is immensely satisfying and rewarding…..make the most of it!