Art, jewelry, DIY crafts: Your imagination is the limit when casting things with epoxy resin—all you need is to create a mold of the shape you wish. It’s easy to make molds of different types and forms. The tricky part is releasing the hardened epoxy resin from the mold. In most cases, a mold release agent is needed to properly remove the casting from the mold you have created.
There are a variety of mold release agents available, but how do you know which is best for your project? Also, what do you do if you do not have any on hand? Let’s take a look at the advantages and disadvantages of common agents, including mold release alternatives you can use when these are not available to you.
What are Mold Releases?
Mold release agents are chemicals that are used to prevent certain materials from sticking to each other. When casting with epoxy resin, you need the resin and the hardener and a release agent to prevent it from sticking to the mold. It does this by creating a lining between the mold and the resin.
There must be no contact between the resin and the mold during the curing process, and failure to ensure this could lead to a ruined casting, mold, or both.
If you work with epoxy resin often, you will understand the need for an appropriate release agent for the mold you are working with. Mold release for resin can be used on silicone molds and is also suitable for polyester resin and polyurethane resin in some cases.
However, unless you work with coated or sealed wood, there is no ideal epoxy resin release agent for wood molds. Its porosity causes the release agent to be absorbed, which compromises the protective layer created. The same is the case with plaster and foam.
Types of Mold Release Agents
Which epoxy release agent should you use? Release agents come in three primary forms: Spray, wax, or lacquer. Of these, the application and mold you use will determine which you should use.
Let’s take a look at the properties and uses of each.
1. Mold Release Spray
Mold release spray is a mix of aerosols and wax, where the aerosol is used as a carrier material. When sprayed, the aerosols evaporate, leaving the wax on the surface to coat the mold.
Best for: Small, intricate molds.
Mold release spray is perfect for detailed surfaces and molds with many corners as the aerosol delivers the wax in small particles that can penetrate small spaces. This quality also makes it one of the best for wood surfaces.
Application: Make sure the surface of the mold is free from any dirt or grease to ensure the wax adheres to it. Once clean and dry, shake your spray can, hold 20–30 centimeters away from the mold, and spray evenly over your mold surface. Make sure to spray only a thin layer and leave it on for about 2–3 minutes before pouring in your resin. Repeat twice or thrice is using a wood mold.
2. Mold Release Wax
Best for: Mold release wax can be hard to get into those tiny corners of an intricate mold, thus it is best used on large, flat surfaces.
Application: Shake the wax container to mix the solvent and wax, which may have separated over time. Next, scoop out the wax and put it on a clean, soft cloth. Smear it over the mold and leave for about five minutes. Once it has set, polish off the excess wax, and you’re good to go. Be sure to clean your mold thoroughly after.
3. PVA Mold Release Lacquer
PVA release lacquer is made up of polyvinyl alcohol (PVA), a synthetic substance that is soluble in water and provides a glossy finish to resin castings. One does not need to polish the casting after applying the PVA.
Best for: Use when you need a second barrier after waxing the mold. PVA lacquer is also ideal for porous as well as sealed surfaces like wood and plaster.
Application: PVA can be applied with a brush, sponge, or spray gun. Apply at least three layers if you aren’t using it together with a wax release agent. Make sure you allow it to dry for about 10–15 minutes between applications.
Can I Use Homemade Mold Release Agents?
Yes, you can. If you don’t have any agents on hand, you can use any of the following everyday items as a mold release substitute or to make your own homemade mold release agent:
- Cooking spray: This is one of the best mold release spray alternatives. Make sure to use non-stick cooking spray.
- Petroleum jelly: Because of its thickness, petroleum jelly is best used as a mold release alternative for simple molds without any small corners or fine detail.
- Talcum powder: Its powdery nature makes it a great silicone mold release substitute, but will not do as well with smoother materials such as sealed wood.
- Vegetable and mineral oil: These can be rubbed into the mold the same way you would line a baking tray.
Need High-Quality Mold Release?
Whether you’re looking for wax or liquid mold release, Plastic Materials Incorporated has it all. We stock a variety of agents for all types of molds. Contact us today to learn more about epoxy resin castings, or visit our shop to view our complete selection.