How do you keep epoxy from sticking to mold?

In this article, I’ll show you how to keep epoxy from sticking to your mold. I’ll also give you some tips about casting your piece so that it won’t get stuck to the mold.

For this tutorial, I’m using Smooth-On’s Mold Star 15 slow cure silicone. You can use any silicone for this process as long as it is mixed properly and poured at the proper thickness.

If you are using a different kind of silicone, make sure that you follow the manufacturer’s instructions exactly. If your mold isn’t mixed properly or poured at the proper thickness, then it may not work as intended.

How do you keep epoxy from sticking to mold?

Here are five of the best ways:

  • Mold Release. It’s simple to use, and won’t leave behind any residue or buildup that could potentially impede your future projects. Recommended for both beginners and seasoned epoxy crafters alike, the main drawback is that you may need to apply multiple coats in order to get things right.
  • Pam cooking spray. A good choice if you already have some on hand, but long-term use can build up a residue that might damage your mold eventually. Definitely not something you’d want to use on silicone molds!
  • Mineral Oil. This one is easy to find and probably already in your home! It’s odorless, effective and will keep your mold free from sticking epoxy for a long time. If it does run low, just add more! Its only downside is that it takes longer than other options to properly sink into the mold and do its job.
  • Baby Powder (talcum powder). Similar to mineral oil in its application method, this one also has drawbacks—mainly related to health concerns over talc inhalation when the baby powder is applied liberally with a duster or canister sprayer (and unfortunately these two methods are required for proper application).

Why is my resin stuck to the mold?

Is your resin stuck to the mold? Don’t worry, it happens to the best of us. This can happen for a couple of different reasons:

How do you keep resin from sticking to cast?

Resin casting is a method of plastic casting where a mold is filled with a liquid synthetic resin, which then hardens. It can be used to create numerous objects from jewelry and figurines to furniture.

To make sure the final product does not get stuck in the mold, it must be properly prepared and cleaned before the resin is added.

  • Cover the inside of your silicone or rubber mold with petroleum jelly or another commercial release agent so that your cast piece won’t stick to the mold.
  • Press your cast piece into the mold so that it fills all of its crevices and details.
  • Pour or press in your epoxy resin as indicated by manufacturer’s instructions. Allow sufficient time for it to dry completely before removing it from the mold.

Does Vaseline work as a mold release?

There’s a popular misconception that you can use Vaseline as an epoxy mold release agent in your fiberglass project. I’m here to tell you that, yes, it will work, but it is not recommended.

Why not? Although Vaseline is great for other applications, this particular oil-based product is not what you want on your next project.

You see, oil does not adhere well to wood and can cause the wood to rot—something anybody working with epoxy should avoid at all costs!

The water in the Vaseline can also seep into cracks and cause damage to the hull of your boat or whatever vessel you may be crafting.

The good news: There are better alternatives. When working with epoxy resin, you need a mold release agent that won’t interfere with the resin curing process and none will do this better than soap and water.

In fact, most manufacturers recommend that after sanding your boat down to its barest surface (120 grit), wipe on a soapy solution before applying any paint or varnish coatings or layering up the fiberglass cloth and resin sheathing.

How much water should be used depends on how soapy you want it; however, I recommend using hot water because it evaporates faster than cold water and also helps degrease surfaces more effectively than cold water alone.

How do you keep resin from sticking to silicone molds?

There are a lot of different types of resin molds and silicone molds, but the general process is pretty simple. You first make a mold of your item in clay (which will later be cured into your final piece). Then you pour some kind of gel into the mold to create a foundation for the resin.

After that, you fill the mold up with resin and cure it. But when you do this, two things can happen to your project: It can peel off (for example) because it’s too fragile for the silicone or because an excess amount was poured in (causing a bigger gap between layers than intended).

Or it might stick to the sides of the mold due to either too much gel or too little gel.

In order to prevent this, there are several additional steps that need to be taken during each step:

  • Use a mold release agent

Will Vaseline keep resin from sticking?

Vaseline can totally be used as a mold release for resin. It is cheap, easy to use, and can be used in a variety of molds. However, it doesn’t last very long, so you’ll want to reapply it between each pour.

To use Vaseline as a mold release for resin:

Apply a thin coat to the surface of the mold using your finger or a soft cloth (like an old t-shirt).

Let dry completely before pouring your resin.

Does resin stick to aluminum foil?

You may be wondering why you would want to keep epoxy from sticking to the mold in the first place. The answer is simple: it’s much easier to remove an item from a non-sticky mold than from a sticky one.

Mold release makes it far more likely that your resin project will turn out as planned, especially if this is your first time working with epoxy.

There are several types of molds and some are more effective for certain projects than others. Plastic molds will work fine for most applications, but metal or aluminum molds are best for casting metal objects or small, detailed pieces.

Aluminum foil can be used as a cheap alternative to metal molds but must be treated with care. It’s important to note that resin does indeed stick to metal and aluminum surfaces very well, so you’ll need a special mold release agent in order to separate the two after they’ve cured. Most resin artists use one of these types of products:

  • Petroleum jelly
  • Grease
  • Wax


So, let’s take a moment to recap.

By now, you should know that the two most common materials used to create molds are silicone and polyurethane.

Each material has its own set of pros and cons as far as how it works with epoxy is concerned.

With silicone molds, the resin is easy to separate from the mold but sticks easily when it comes time to put them together; whereas polyurethane molds are hard to separate but easy to assemble.

Be sure you keep these characteristics in mind when deciding which material would be best for your project.

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Martin Flood

Martin Flood has been working in the construction industry for over 20 years as a general contractor with expertise in remodeling projects that are large or small. He has furthered his career by specializing in epoxy resin flooring, providing excellent service to both commercial and residential clients. Martin’s experience enables him to offer professional advice on how to choose the right type of project based on your needs and budget.

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