And it sat in the closet for a year because there was nothing that I really wanted to cast. Working on the Chew customs for Custom Con and having Gallus Sapadillo as one of the accessories has really given me the kick in the butt I needed. Since I ended up sculpting a Sapadillo out of apoxie, I figured this would be the perfect thing to use on my first attempt at mold-making and casting.
The kit comes with everything you need to make a one-part mold and cast your original. The object I cast is small, so I ended up with leftover silicone. I could have made another mold for something else small like a head, weapon, body part or something else from an action figure. Setting up the object and container and mixing and pouring the mold takes less than 10 minutes. Then you’ve got to let it cure for 4-8 hours.
I let it cure for the maximum amount of time. After 8 hours, I pulled away the mold support, packed up the clay and used an exacto knife to carefully slice along the stalks of the mold. The mold itself is pretty flexible and you can bend it and just squeeze out your original.
Making a casting takes about as much time as it took to set up the mold. The two-part resin in the pack cures in 3-7 minutes, once mixed. This means you’ve got to work quickly and carefully. I over-poured a bit the first time and completely misjudged the amount of resin I needed. I forgot to mention this: you should heat the mold before you mix your resin and make your cast. Heating the mold helps it cure and helps the resin flow better across the mold. The directions said to heat the mold for 10-15 minutes at 140 degrees F. If you factor heating the mold into the casting process, the total time for casting is around 30 minutes.
I waited the full 7 minutes for the resin to set and squeezed out the cast. Not too shabby for my first attempt! You can see a few details didn’t fill in: the tip of one stalk; the leaves on top; and the bumps on the stalks. The over-pour is evident and something I has to cut/sand off. I can use apoxie to fill in the parts that got missed in the casting process. The original in gray is on the left and the cast in yellow is on the right.
To try to get all of the details to fill in, I popped the mold back into a plastic cup and then poured the resin. I thought that maybe the mold was expanding a bit as the resin cured and perhaps that's why the casting didn't pick up all the details of the mold.
Unfortunately, the cup idea didn't help at all. Next I tried using a toothpick to put resin in the parts that don’t fill in and then I poured the rest of the resin into the mold. This was the most successful technique so far, but still produced a less than perfect casting.
I made one more cast and still did not get a perfect copy. The last cast (casting number four) tore the thin parts on the top of the mold, so there was definitely a law of diminishing returns at work. Here are all three of the four casts and the original – top left is original; top right is first cast; bottom left is where I tried to limit expansion of the mold; and bottom right is where I used a toothpick to fill in the details.
Lessons Learned
1. Next time I cast an object with a similar bottom, rather than gluing the object to a flat surface, I will glue something to the bottom of the original to give it a little height and let the mold flow under the object. I think this would help pick up the small details of the object that got missed when I made the cast. Something like this:
2. Because you’re mixing a two-part resin, you’ve got to figure that when you’re doubling your volume – that is when you pour your part B into its cup – that’s not the final volume of your resin: it’s half the final volume.
3. Don’t over-pour! The resin will expand slightly as it hardens. Don’t under-pour either: try to fill the mold so that the resin level is even with the top of the mold. Really the only problem with over-pouring is that you have more clean-up to do on the cast object and you're wasting your resin.
4. Using the toothpick technique to pre-pack resin in the detailed parts of the mold really works. I think it wasn't completely successful because the resin I have cures so quickly, that in the time it took me to use the toothpick, the rest of the resin began to harden before I could pour it into the mold.
Although I never successfully cast an exact copy of my original, I still feel really good about the few casts I did make. I think that with a little more practice and experimenting with different resins, I'll be able to eventually make perfect casts. And once I do that, maybe I'll make a bootleg “the Query” action figure after all.
optimistic