How to Make Resin Molds for Mold Making

Posted by ComposiMold on 30th Oct 2020

How to Make Resin Molds for Mold Making

Mold making is a process that you use to duplicate other objects, but mold making will take some experimenting. The reason ComposiMold exists is because I used to make a lot of mistakes and I was frustrated at wasting my money on molding materials that I'd only use once.

A RESIN can be epoxy resin, urethane resin polyurethane resin, acrylic resin, polyester resin, or vinyl resin. 

The mold making process is simple, but there are many different ways to duplicate something. So you are in a good place to start with ComposiMold. Have you checked out our ebook? Free E-Book

Start with that and some of the you might like is

I also recommend starting simple. A shape that is flat on one side. A relief sculpture.

Another option is to use the ImPRESSive Putty. It makes the mold making process very simple and much easier to conceptualize. The Putty is heated and you press it over your part. After it cools to solidify, you have your mold and you pour or press in your casting material. Because it’s so straight forward, this is a great material to learn mold making. We have been using it for children down to about 8 years old (with adult supervision because the Molding Putty can be hot out of the microwave until it cools). 

Mold making is the process used to duplicate three dimensional models or objects. A model is any object that has depth, and an original model can be made from almost anything. If you were making your own object to mold, you might use clay, rock, or plastic. Through the use of a mold making material a negative, or a reverse, of a model part is made, the negative can then be used to cast a second part that is the same size and shape as the original part.

Simple parts such as relief sculptures can be duplicated by using a one part mold. The casting material is poured or pressed into the mold indentation. The casting material can range from clay, soap, chocolate, concrete, liquid plastic, play-dough, and metal castings.

You can make two part molds or even three or more part molds. Mold sizes can range from a few millimeters to many feet in size. Mold making is used in industry to make duplicates of a wide variety of creations ranging from car parts to Christmas ornaments. More complicated molds may include a variety of molded parts, rigid parts of the molds, inserts, a variety of resins and fillers, and a lot of setup and thought.

At home mold making is typically performed using a rubber mold making material that can be poured on or around the object to be duplicated. The mold can then be filled with casting materials of your choice. For example, many cake decorators or chocolate makers use molds to create unique shapes from their chocolates or use molds to shape fondant into special shapes. Home soap and candle makers duplicate unique shapes and designs. Hobbyist use molds to make components for their trains and to make improvements to the backdrops and sceneries. Even fishermen enjoy molding their own unique fishing lure

Mold making can be fun and useful. With patience and persistence, you can mold and cast just about anything. You can make unique gifts and fix broken parts. To learn more about molding, casting and the products associated with Mold Making visit

So why use a reusable mold making material? Re-usable Mold Making provides many benefits to you as the maker, the artist, the hobbyist, the gamer, the crafter:

1. Stop spending money on molds, and start making.

2. Enables you to create dozens and dozens of new molds anytime you want.

3. Great shelf life, so it's there when you want it.

4. Use what you want for big molds, little molds, simple molds, and complex molds.

5. Eco-friendly and safe for you to use.

6. Super easy to use: no mixing or weighing or using too much.

Mold Releases:

For the mold making with ComposiMold, we have a mold release available, but you can just use vegetable oil or mineral oil…or waxes…or silicone sprays… You may like spraying a little with Bubble Buster to reduce bubbles from sticking to your part. Spray this on after you add the mold release.

Urethanes: I recommend a barrier made with talcum powder (baby powder) because some polyurethanes are sensitive to the moisture in ComposiMold.

For epoxies: I usually stick with the vegetable oil or mineral oil…a very thin coating, and then I wipe it off.

Tip 1. Start small, start simple, it’s reusable. Everyone wants to start out with an action figure, hollowed out double sided figurine, or thin walled toy motorcycle. Go for it. You Can duplicate almost anything. But we recommend doing this as your second or third mold, not as your first mold. Remember, ComposiMold is re-usable, so you don’t have to worry about messing up. You can always re-melt and start again. That’s surprisingly hard for some people to grasp, as they have been so engrained to think of silicone mold making or even plaster molds where you only have one chance to make a mold. No, that is absolutely, not the case with ComposiMold or ImPRESSive Putty. You can make as many molds as you like. So start simple, find success, and build up to advanced mold making techniques.

So what do we mean by starting simple? Look for (or you can make with Plasticine or polymer clay or wood) a piece for your first mold that has a flat side. This is called a relief sculpture. It doesn’t have to be completely flat. It could be tall or short as long as one side is flat surface to it so you can set it into a simple mold box such as a cup or container. Also, look for pieces that don’t have thin protrusions coming off at different angles, and don’t start with extremely contorted shapes. You can definitely mold it, but it will take some practice, which is why simpler shapes are create a nice solid mold making experience.

2. Adhere your bottom to the bottom: There’s one thing that even the expert mold makers still forget to do when you’re in a hurry making a mold. The number one mistake that occurs when making molds with ComposiMold is not adhering your part to the bottom of your mold box. Lightweight parts will float. I still make this mistake, typically when I’m trying to make a really quick mold and trying to take a short cut. Plastic floats, so adhere it to the bottom of your container. If your part floats in water, it will float in ComposiMold. To adhere it, hot glue it to the bottom of the container. You can also hold down smaller objects with polymer clay or double sided tape. For big objects, you can screw the part down to the bottom. Another way to hold your part down is to pour a little ComposiMold around your part while it is in the mold box, let that solidify, and after it has solidified, pour more ComposiMold. The first ComposiMold will hold the part in place.

3. No Boiling and pour cool: Here’s a tip for melting ComposiMold and ImPRESSive Putty. Don’t let the mold making materials boil too much as it will degrade the mold making materials over time. Also, overheating the ComposiMold creates bubbles in your ComposiMold. We give recommended times for melting the material in the microwave, but of course, every microwave is a little different so start with short intervals of 30 seconds to a minute until you understand how it’s going to melt. You can also melt in a double boiler or chocolate melter. That’s a little slower, but will allow you to control the temperature easier. If you do boil the ComposiMold, don’t worry too much, you can let the ComposiMold cool slowly, or even better is to keep the ComposiMold warm so it stays melted and the bubbles will rise up and out, and you can still make awesome molds.

When making a ComposiMold mold, you want to typically pour the ComposiMold OVER your part. You don’t want to place your part into the ComposiMold. By pouring the ComposiMold over your part, you’ll get fewer bubbles stuck under your part and you’ll typically get nicer molds.

MELTING ComposiMold: To melt, heat the ComposiMold to 130 degrees F. (Do not exceed 200 degrees F). This can be done in a double boiler or a microwave. When heating in the microwave start with short intervals of 30 seconds. The 6oz. container should take about 45 seconds to fully melt.

After melting, stir the ComposiMold gently to let the temperature equilibrate and cool before pouring your mold. It’s perfect when it has a warm honey-like consistency at (130 F-140 F).

4. Use Bubble Buster and look for bubbles in the cracks: Now in many cases, you will still have bubbles form while making the mold. This is going to happen no matter what mold making material you use. The nice things about ComposiMold is 1. You can see the bubbles, and 2. You can get rid of the bubbles. We have a lot of tips of how to remove bubbles, and we’ve made a separate video just on this topic, so please watch that video for more details, but here are the key tips:

1. Use Bubble Buster

2. Pour ComposiMold when it is cool, but still a liquid. It will be thicker, but fewer bubbles will form. It will still pick up All the details.

3. Use a paperclip to pull bubbles away from the surface of your original. You don’t have to pop the bubbles, just pull them away from the surface…This is especially important where there are undercuts, or in crevices where the bubbles get stuck.

5. Don’t worry about the spill: Here’s another tip: You will probably spill ComposiMold or get ComposiMold on your fingers or clothing at some point. Don’t panic. In most cases, just let ComposiMold cool and peel it away and re-use it. It’s still good. You can also wash ComposiMold away with hot soapy water. If you have it on your fingers, let it cool and pull it off.

Some people have suggested cutting up ComposiMold before melting it. You can, but you don’t need to. It melts fine either way. But here’s a small tip, you don’t need to melt all of it every time. If you only need a small amount, then just melt it a little. If you need more, melt more. You can mix it together. Even ComposiMold that has partially hardened can be mixed with more ComposiMold. If you are pouring ComposiMold on to other ComposiMold that has already hardened and you want it to stick, just melt it a little with a hot air gun, heat gun, before pouring the other ComposiMold on top.

6. The Container will crash, the ComposiMold won’t: Now the container that ComposiMold comes in IS microwavable, but it will fall apart well before the ComposiMold does, so just place the ComposiMold in a microwavable container like a Tupperware dish. Keep it covered, and it will be good for a long, long time.

7. Store your molds in a cool dry place in a Ziploc: How to keep your molds. Sometimes you make a mold that you want to keep. You can. Just cover your mold by placing it in a Ziplock bag or other sealed container, keep it in a cool, dry place, and it should last you several years with no problems. And of course, you can re-melt it anytime you like.

8. Fix a mold with a heat gun: You can patch a hole in a mold by melting some ComposiMold and brushing it over the hole. This works really well if you place your original in the mold while you are fixing the whole. You can melt the ComposiMold with a hot air gun.

9. Clean your mold with a cold, wet wash cloth: Use a cold wet wash cloth and wipe away any particles. If you need to, rinse it under cold water and then make sure it has time to dry out. Make sure it is dry or it will be slightly sticky. If it is sticky, you may need to re-melt and re-make the mold. It will be fine after that. If you are using non-food casting materials, you can also filter the ComposiMold through cheese cloth or a medium or large hole paint filter. Don’t try to filter the ComposiMold through a coffee filter. It won’t go through.

ComposiMold’s greatest advantage is its reusability. All you have to do is remelt your mold and pour a new one!

And have fun. That’s why we’re here.