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Epoxy resin allows both artists and do-it-yourselfers to create any shape they wish. Especially if you want to use self-made forms, there are no limits to your imagination. But to be able to release the hardened epoxy resin, the casting, well from the mold, a release agent is needed. We describe the advantages and disadvantages as well as the areas of application of the various epoxy resin release agents and how best to use them to grease your silicone mold.
Table of Contents
What are release agents for epoxy resin needed for?
Release agents are generally understood to be substances that prevent different materials or articles from sticking or sticking together.
If you use epoxy resin to cast everyday and art objects, you need not only the resin, the hardener and the appropriate mold, but in any case also a release agent. You should always grease the silicone mold you use. This prevents the hardening epoxy resin from sticking to the mold. This applies not only to smaller castings, but also to furniture where epoxy resin is embedded or worked into other materials, such as wood.
When making molds using epoxy resin and glass fibre mats, it is also important to process the negative mold beforehand with a suitable release agent for epoxy, otherwise the resulting mold cannot be released and all the effort was in vain.
For this purpose the mold must be completely lined with the epoxy resin release agent; there must be no contact between the resin and the mold. If the resin adheres to the mold during the curing process, the mold is damaged and the casting is usually not usable.
As a rule, release agents for epoxy resin are also suitable for polyester resin, sometimes also for polyurethane resin.
It should be noted that there is basically no ideal epoxy resin release agent for wood, as this is a porous, i.e. absorbent, substrate. Such surfaces must be sealed before treatment with release agent, otherwise the release agent will be almost completely absorbed. Such materials include wood, plaster and foam. So when we talk about a good epoxy resin release agent for wood in the following section of our guide, we assume that the wood is sealed.
If you want to use a release agent for epoxy resin casting, you can choose between a release spray or a release wax. Your choice depends on the type of application. A release spray for epoxy resin is best suited for very small and detailed molds, as it can be sprayed on and does not have to be rubbed in like a release wax.
The spray works via a combination of wax and aerosols. The latter act as carrier material and apply the protective wax layer to the mold. While the wax layer remains on the mold, the aerosols evaporate within a short time.
Fields of application
A release spray is particularly suitable for molds with many smaller edges and corners, because the spraying process distributes the release agent optimally everywhere. If you want to achieve a particularly even surface when casting epoxy resin with the release agent, you can polish the spray afterwards; however, this is not a must.
First of all, the substrate must be completely cleaned of all grease, oil and dirt residues. This applies not only to release sprays, but also to release waxes and PVA release lacquers. Especially oil and grease prevent the adhesion of the release agent; it virtually floats on a kind of oil slick and thus cannot develop its properties. After curing, the casting material does stick to the mold and the mold and casting can be damaged.
After thorough cleaning, shake the can well with the release spray. Now spray the mold as thinly as possible with the release spray. Take care to cover all angles of the mold and keep a distance of 20 to 30 cm from the mold when spraying. Wait two to three minutes. Now polish the release film with a lint-free, soft cloth if necessary.
New forms should be treated in this way several times, preferably three times. After each spraying, allow the mold to flash off overnight.
Recommendation: Stoner mold Release Spray
The Stoner Release Spray with Wax is a mold release agent for various applications and materials. It facilitates the removal of the casting and offers the user an easy and pleasant handling. The Stoner Release spray also has other advantages:
From us there is a clear recommendation for the Stoner Release spray, as it offers the user in principle all the positive properties required to release a casting from epoxy resin. For the separation of silicone, a release wax or a release petroleum jelly can be used.
Unlike the release spray, release wax is not available in a spray can, but as wax. Mostly it is liquid, so that it can be easily removed from the container with a cloth. The container is simply opened and the wax is poured onto the cloth held in front of it. You can then use it to grease your silicone mold. But the release wax is also suitable for surfaces other than silicone.
After the mold has been treated with the wax, a matt surface is created, which can be polished with a lint-free cloth. In this way the surface becomes highly shiny.
Fields of application
Release wax is ideal for the treatment of large and flat surfaces. Smaller details should rather be sprayed with a release spray, as it can be difficult to work the release wax evenly into smaller angles with a cloth.
If the mold has been used several hundred times, it usually has to be thoroughly cleaned once and thus freed from all wax residues. This can be done with warm water and some steel wool.
The release wax is first shaken well before use. This allows the wax and solvent to recombine, which can separate after long storage. After shaking, the wax is removed with a spatula and applied with a clean, lint-free cloth. Wait for about five minutes and then polish the release wax with a clean cloth. New molds require the application of a second coat. Again, one night should pass between each release coat.
If you want a shiny surface, you should additionally treat the wax release layer with a PVA release lacquer.
Recommendation: Orca Shimmer mold Release Wax
The Orca Shimmer Release Wax can also be used for all types of resin. It offers the user many advantages:
Important when using the wax is the flash-off time. This should be observed to prevent the wax and resin from mixing. The resin should only be poured in when a tack-free film has formed in the mold.
Because of the easy use and the really enormous yield, we give Orca Shimmer release wax a crystal clear recommendation!
PVA Release Lacquer
PVA Release Lacquer is also used for better demolding of castings and is sprayed onto the negative mold, similar to release spray. This creates a film similar to a film on the mold. The release lacquer is based on polyvinyl alcohol and promises the formation of an optimal release layer.
Fields of application
PVA release lacquer is often used in combination with a release wax for epoxy resin. It serves as the last layer between release wax and the epoxy resin. It not only ensures excellent demoldability, but also a high-gloss surface. PVA does not need to be polished after application.
PVA release lacquer is also used to treat porous or sealed surfaces, such as melamine resin press plates, plaster or wood.
The release lacquer for epoxy resin can be applied with various aids, either with a spray gun or with a sponge, brush or foam. The best way to do this is crosswise, i.e. apply first lengthwise, then crosswise and then again lengthwise. Do not apply new paint in between. Ensure that the paint is applied thinly and evenly and then allow the mold to flash off for between five and ten minutes.
After demolding the casting, you can easily remove residues of the release lacquer with lukewarm water and a sponge.
Recommendation: Partall PVA Release Agent
The PVA release lacquer from Partall is the ideal epoxy resin release agent for wood, silicone and other materials. It offers the user a whole range of advantages:
With this product we could not find a single disadvantage. It definitely keeps what the manufacturer promises: easy handling with high yield and perfect demoldability of the castings. The release lacquer from Partall is the perfect release agent for wood in combination with Epoxy Resin, but also for other types of Resin.
- Partall Film #10 is a water/alcohol-based polyvinyl alcohol (PVA) mold release agent that forms a barrier between parts and mold surfaces that are still curing (green or recently reconditioned molds can be reactive).
- Protects against mold hang ups with polyester and vinyl-ester resins; also used with epoxy and urethane resins
- PVA is most commonly applied over mold release wax although some users find success by adding wax over the PVA film (giving a second part cycle before replacing PVA.)
Tips and Tricks for easy Demolding of Castings
There is no royal road to release a casting from the mold. The method of release depends strongly on the size of the mold used and the design of the component.
Always loosen the edges of the casting first. Most components can be released from the mold by this alone; simple components already slip out when you turn the mold over.
If the release does not succeed at the first attempt, you can help with demolding wedges. These plastic wedges are available in every well-positioned hardware store or via the Internet. They are also perfect for opening two-part molds.
If you have the possibility, you can blow compressed air between the mold and the cured component. If the casting still does not come loose, try tapping gently on the mold with a rubber mallet.
Which release agent for epoxy resin you use depends mainly on the mold into which you want to put the resin. For two-dimensional molds, we recommend a release wax, whereas for a detailed mold, you can rather use a release spray to save work. We hope that we have been able to give you a solid overview of the various epoxy resin release agents.