Introduction: DIY Silicone Mold for Resin Casting

About: A wife, mom, and maker, making heirloom quality wood artwork for the bold home.

Being the owner, designer, and maker of a custom product-based business can sometimes create restraints, such as how much product that sole person can physically create while managing the other aspects of the business. I have been acutely aware of this bottleneck for some time. I am not at the place in my business to be able to hire on employees to help get more product made and out the door for replacing sold products in local retail spaces or in preparation for pop-up shops and art gallery events. Since I do enjoy working with both wood and resin, I knew there had to be a way to utilize the flexibility of resin to cut down on my production time while still honoring my craft of creating objects from wood. So, I did some research on how to make a custom silicone mold so that I could replicate some of my one-of-a-kind wooden pieces in order to up my production rate and stay true to making unique pieces.

Step 1: The Template

For the particular art gallery show I was in the process of making product for during this time, which was being held at a wine and cheese shop, I decided that cheese platters would be an appropriate thing to try out this new mold making process on. First, I needed to make the template. I chose to use a piece of scrap box elder wood to carve the template. The piece was rectangular to start with, I created a squarer shape by cutting off the excess on the bandsaw. Then I used my 4.5-inch angle grinder with King Arthur’s Tools Holey Galahad attachments (course and medium) as well as the King Arthur’s Tools mini grinder, Merlin II to carve the wood to shape. To finalize the shaping, removing any remaining high or low spots, and make a smooth surface for the mold process, I used the King Arthur’s Tools Guinevere sanding system. Once it was to its final shape and smoothness, I used my Gear Heart Industries electric branding iron to make my mark on the bottom of the piece. This also helps identify it as the original piece.

Wood is porous and the silicone I would be using to make the mold was liquid, I wanted to ensure that the liquid did not seep into the wood pores, creating a rough texture on the mold and possibly making it difficult to remove the template from the cured mold. To avoid this risk, I used water to wet the wood platter, let it dry, and then applied a sanding sealer. Once the sanding sealer was dry, I took it a step further and applied a spray enamel. This left the wood platter with the pores completely sealed and a very shinny surface

Step 2: Making the Mold

To make the mold, I first needed to make a container slightly bigger then the wooden platter to be able to contain the platter and the silicone. I created a square container out of corrugated plastic. I used a box cutter to cut the corrugated plastic and an industrial glue gun and glue to glue the sides in place on the base of the container. I choose these two materials, the corrugated plastic and the hot glue because the liquid silicone would not stick to them. Once the container was created, I lightly hot glued the wood platter to the bottom of the container, which means when completed, the bottom of the platter would become the top of the mold. Lastly, before pouring the silicone, I sprayed the inside of the container and around the wooden platter with a mold release spray.

For the silicone, I used a 2-part liquid silicone from Smooth-on. I mixed equal parts of the silicone and then poured it over the top of the wooden platter into the container. I poured enough that the entire platter was covered with at least ¼ inch depth across the whole thing, some places being thicker then others give the nature of the shape of the platter. This particular liquid silicone has a 6-minute working window and cures within 30 minutes. This allowed me some time after pouring to make sure the container was sitting level so that the resulting mold would also be level.

After the silicone had cured, it was time to de-mold the mold! This was pretty simple, just used a box cutter knife to cut along the hot glued joints to get the corrugated plastic off of the fully cured silicone mold. Then I removed the wooden platter from the silicone mold. All of this went smoothly without any issue at all. I removed a bit of flashing (thin silicone) around the top of the mold just to reduce the possibility of issues when pouring the resin. This was also easily done with a standard box cutter knife.

Step 3: Resin Casting

Now that I had a completed custom mold, it was time to try it out! I went with Ecopoxy Liquid Plastic, using the 2:1 mixing ratio. That is mixing two-parts A to one-part B. The 2:1 ratio cures much faster then the 1:1 ratio, and since the depth of the pour would be less than 3 inches, it is perfectly safe to use the 2:1 ratio without any concerns for overheating and cracking. For the test run pour I split the total resin needed, which was 24 ounces into equal 12-ounce parts. I tinted one-part orange and used a copper metallic color in the other 12-ounce part. I poured both into the silicone mold, added some cedar wood shavings for texture and mixed. I used a regular propane torch to release tension on the top of the resin and get rid of the bubbles. I let it cure for about 40 hours and then I de-molded it. It came out perfect! There was a tiny bit of flashing on the bottom that I later cleaned up with a handheld Dremel tool, but that was not a big deal at all.

Step 4: Conclusion

When all was said and done, I ended up making 3 total molds of the platter, which allows me to have 3 platters poured and curing at once. This means I can make 6 to 9 of these platters in a week. This is a HUGE time savings. If I were to try and carve, sand, and finish the same number of trays, it would take me at least a week and a half to two weeks and I wouldn’t be able to work on anything else during that time. Plus, I love that I can still make each individual platter unique by playing with different color tints, metallic pigments, and additives like the cedar wood shavings or the pine cone.

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