Top 5 Lessons Learned - Resin and Silicone
We’ve only been pouring resin and silicone for about 2 years now, but we have learned a lot along the way. Hopefully this helps out someone out there making their own magic.
Lesson #1 - A little heat goes a long way
Accidently oven cured resin
Resin cures faster at higher temperatures. Most resins even produce their own heat as they cure, which accelerates the curing process, which produces more heat, which…etc etc. The thickness of resin will also accelerate this process. So what shouldn’t you do? Put it in the oven. Seriously don’t do it. The above picture demonstrates the result after only 5 minutes of a very low temperature. Not only did it cure fast, but it cured un-evenly. This soft resin at the bottom of the silicone beaker, which made a mess when we assumed it was cured all the way through. If you want to speed up how fast your resin cures, it is recommended to put it in warm water (safely separated by another container of some sort). Pro tip, we also found that wrapping a seedling heat mat around our resin container worked quite well. We have even heard that using a heat gun or blowtorch is an excellent way to remove pesky top-layer bubbles during curing. Which leads us to our next lesson…
Lesson #2 - Dealing with Pesky bubbles
An excellent little degassing chamber
Too many of our resin pours were ruined by excess bubbles. Magical crystals just don’t look quite right with them. Stirring resin can add a lot of bubbles. Pouring resin can add bubbles. Air can get trapped in your mold or extra materials, which also introduces bubbles (especially wood). Our personal favorite way of dealing with this? A degassing chamber. Small chambers aren’t terribly expensive and they are well worth it. This is our most used tool when doing both resin and silicone pours. How does it work? You put your liquid inside the chamber, and using a motor, it attempts to remove all air from the entire chamber. The result is all bubbles are slowly pulled out of your liquid. You even have the option of putting in your liquid before your pour, or if your mold will fit inside, after. Pro tip: since resin is more viscous when it is warm, the degasser works a lot faster at 70 degrees or above. We had problems with the top “foam” bubbles never popping when at around 55 degrees. Pro tip #2: put a light, porous surface such as a tiny bit of foam or sponge on top of the resin while it is inside the degassing chamber. This will help pop the top bubbles and accelerate the process.
Here are some alternate methods for avoiding bubbles:
Stir slowly (stirring too fast adds a lot of air)
Don’t stir with porous things (like popsicle sticks and other woods)
Spray light alcohol mist to pop top bubbles (alcohol dissolves resin)
Use a pressure pot (must wait until resin/silicone is fully cured inside chamber)
Place on something that vibrates (dedicated equipment even exists for this)
Cure at a low temperature (< 65 degrees) as bubbles will have more time to rise to the surface
Cure in thin layers
When pouring resin on wood, “seal” the wood first with a first layer of something (this will prevent bubbles from escaping from the wood into your resin)
Lesson #3 - Make your silicone forms as small as possible
Silicone is quite durable, and it isn’t cheap (we buy in bulk for a little over 50 cents per oz). For most molds, a couple mm thickness is all you need. Just take a peek on Amazon and see how thin their molds are. The mold only has to be thick enough so that it can handle the weight of your resin and doesn’t deform (this was a big deal when casting spheres). It is worth spending time to build a mold that fits the object you are casting. We recommend using hot glue and foam boards, as they are fast, cheap, and easy to work with. We have also found that the right sized plastic jar works well. For custom circular molds, we make a cylinder out of thin plastic cutting boards. Without the right form, you might find yourself pouring $40 of silicone into a small looking mold, and only have it half-fill. You have been warned.
Lesson #4 - Silicone elasticity matters
Our secret weapon for mold making? Highly elastic silicone (Shore Hardness of < 10A). The main advantage was that we could making a single piece mold; normally, a lot of things have to molded in two or more parts, due to the shape of the object. But since this highly elastic silicone can deform, we were able to make irregular parts in one piece. No more mold-lines on our crystals! Just make sure your mold is thin enough; pour this stuff too thick and it will be extremely difficult to stretch enough to wiggle your part out. Also keep in mind that super elastic isn’t always the answer. In some cases, you want more rigid molds to prevent deforming while the resin is curing. Examples of this are flat objects or spheres; we tried making a sphere mold out of super elastic silicone, and it looked like slightly squished.
Lesson #5 - Everything in between
Here are some additional pro tips we learned along the way
Wear some sort of eye protection. Getting resin in your eyes is terrible business. You can’t just wash it away (you will understand the first time you get resin on a finger). In our experience, it seems very unlikely that resin will reach your eyes, but all it takes is one accident; a too-quick stir, or a sudden jolt of something stuck.
Get some lunch trays (or other flat surfaces). You will often find yourself moving your resin around to cure, or to get it out of the way. Plus you want something under it to prevent drips from getting on your other nice things. And curing resin usually has to be flat. Lunch trays are a cheap way to accomplish all this. We have even found that resin doesn’t stick to them very well.
Prototype it! This is a general crafting tip, but it applies here. Too many times we have done big pours only to realize we had the wrong color pigment, or our mold was poorly designed. We have started doing mini-pours when testing new things. Nothing is worse than rolling the dice on a big pour, only to first realize your mistake.
Mold release! Think your object will easily slide free of your mold? Oh poor sweet child. In some cases it will (such as thin objects), but there have been times where our piece was so stuck, we had to drill a screw in and then use plyers to pull it out. A little bit of Vasoline goes a long way; this applies to both molding an object, and doing a resin pour. They even make fancy Mold Release sprays now.
Track your dye amounts. If doing consistent resin pours is your goal, track how many drops of dye you use per oz of resin. This is especially true of opaque pigments such as white, where a single drop can make a huge difference.
Scrape the edges! When mixing 2-part silicone or resin, scrape the bottom and sides of your container well. This is where the liquids tend to stay unmixed, and can result in soft spots, or even goopy uncured texture.
Use tiny beads to approximate your liquid usage. Unsure of how much silicone your form needs? Fill it with small beads, and then pour those beads into a beaker to measure their volume. When approximating how much resin you will need in your silicone mold, you can just use water.
Have small molds for excess resin. You will almost always have a bit a resin after a pour, even after using the “bead” method above. We found it best to have a few small molds at hand (tiny crystals or creatures) to save that excess resin.
Always have a roll of paper towels or rags on hand. Maybe you think you don’t need it for this pour. It’s just a little pour and you are very careful by now. You would be wrong.
