How to use resin casting molds – silicone epoxy molds

How to use resin in casting molds

Using casting molds with resin is a fun and easy way to get crafty. There are so many options out there, including plastic and silicone casting molds for resin. Let’s get into the basics of what you need to know to create something you can’t wait to show off!

What are casting molds?

filling a silicone molds with clear epoxy resin

Molds are hollow forms that you pour casting resin into to produce a shape. The structure and finish of the mold will impart onto the resin as it hardens. Once the resin fully forms, you remove the resin from the mold, and it retains the mold shape.

What casting molds should I use with resin?

molds for resin

Molds specifically designed for resin will give you the best results. These include silicone molds and polypropylene plastic molds. Resin molds release resin easily once it cures completely.

Other molds, like candle and ceramic molds, don’t work well with resin. In fact, the resin may stick to the mold and not release at all. If you don’t believe me, here’s what happened when I used a soap mold with resin.

What kind of resin should I use with casting molds?

For mold projects, you should always use a casting resin. This type of resin mixes in a thin consistency, making it easy for bubbles to escape the resin before it starts to cure. These resins also do better when poured in thick layers as compared to countertop resin, which is meant for coatings.

For mold projects where I’m pouring 3 ounces or less (total) of resin, I use the Resin Obsession super clear resin. It cures hard and clear and is ready to demold in about 12 hours.

For resin mold projects where I want to pour more than 3 ounces in one pour, I use the Resin Obsession deep pour epoxy resin. Not only is this an excellent resin to use in molds, but you can also use it for thick pour resin projects like river tables.

How do I use casting molds?

Here comes the fun part. It’s time to use your resin with molds!

Mist a light layer of resin mold release over your mold 30 minutes or longer before you plan to fill it with resin. This will make it easier to demold your resin castings, plus prolongs the life of your mold. If you are wondering if this step is vital, here are three reasons why I always use mold release.

mixing clear resin in a cup

Measure and mix your casting resin. Every resin has specific instructions that should be included with your resin kit. Don’t deviate from these instructions! Follow them strictly, so you don’t find yourself with a resin disaster. If you haven’t used resin before, this article explains how to measure and mix resin in five easy steps.

adding glass beads to resin

Pour the resin into the mold. You can add fun stuff like found items, charms, glitter, stickers, or, like shown here, glass beads.

pouring colored resin into a mold

If you want, you can color the resin before pouring it into your casting mold. I like to use colors for resin as they will give me the most reliable results and are least likely to cause curing problems.

What other techniques can you try with resin casting molds?

Dust some Pearl Ex powder into the mold with a paintbrush. Get all the surfaces, plus the cracks and crevices. Tap the mold to remove the extra, then fill with resin.

The powder will stay on the surface of your resin charm after demolding.

remove bubbles with a heat gun

Before setting your resin aside to cure, go over the surface with a heat gun. This will pop the bubbles that rise to the resin surface.



cover castings with a plastic dome

Because resin has an affinity to collect dust and pet hair, cover your casting molds with a plastic dome after you have filled them with resin. Leave this dome on for the entire curing time.

Resin drying time depends on the one you use. Most epoxy resins need 12 to 72 hours to dry. Make sure the resin is formed before you demold. If it isn’t, you might misshape it as you demold and may not be able to get it back into the desired form.

demolding resin coaster from geode silicone mold

Once the resin is dry, peel the mold away from the resin while grabbing a formed resin edge. Be firm but gentle. It should feel like you are peeling the skin off a banana. If things aren’t coming out quickly here, you can always add soapy water to make this step easier.


How do I care for casting molds?

Now that you have found a mold you love, you want to make sure it’s going to perform for you for a long time! Keep it clean, dry, and flat in a space away from direct sunlight. Resin casting molds can warp and crack if neglected.

Here are some of my best silicone mold care tips for your silicone resin molds.

How do I know if my casting molds will produce jewelry and crafts with a glossy surface?

To know that, look at the inside of the mold. Whatever the mold surface, that same finish will finish the resin the same way. If you want to make charms with a shiny finish, you want to use molds with the same shiny surface.


What happens if you use a casting mold with a dull surface?

Your casting resin will cure no differently than using a resin casting mold with a polished surface. The only difference is that now you have to decide if you will try to make the resin charm surfaces shiny. The good news is that it is pretty easy!

Use a couple of light layers of our resin gloss sealer spray to bring back the shine to charms made with frosty surface molds. This spray is also fantastic for sealing flowers before including them in resin to prevent moisture stains!

What are some of my favorite resin casting molds?

Well of course, it depends on what I want to make! Here’s are a few of our customer favorites that might inspire your creativity too.

 

Want to learn more about using resin casting molds?

Then you will enjoy a copy of my PDF ebook, Resin Fundamentals. I share the important details you need to know to have success creating with resin from day one! Buy the book now, and you get a download link in minutes!

Unpublished Blog Posts of Resin Obsession, LLC © 2021 Resin Obsession, LLC

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