128: Kryptonite

Man, I love making props.

My friend Mike is putting together a Lex Luthor costume for a nerd wedding, and he came to me with a request. He needed some kryptonite on a chain to complete the look.

I gave it a lot of thought, looked at a lot of pictures, and figured out that this would probably require me to learn a new skill. It’s a green glowing rock, and I couldn’t think of anything that could capture the translucency other than poured resin. I don’t have any experience in resin casting, so I accepted the project. It’s a good excuse to figure it out.

I do have metal casting experience, so I know the basic steps:

1. Make something
2. Make a shell around it
3. Take the original thing out
4. Pour the new thing into the shell

Pretty straightforward, but there are so many possibilities for each step. Since resin is pretty expensive, and I was trying to keep the costs down, I’d have to cheap-out on the other stuff.

I roughed out a basic shape in wax. I like wax because it works like modeling clay, but it’s really easy to reclaim. You just melt it. It also smooths out beautifully. I don’t like wax because it’s hard to clean off tools, tables, clothes… really anything.

After a few minutes in the freezer, it was hard enough to scrape a mineral-like finish into. I sharpened up all the corners and flattened off all the faces. I’m going for a look halfway between a rock and a crystal.

This is another reason I chose wax. No complicated moulding. If I needed to preserve the original, I would probably have to simplify the design, and use some sort of rubber or silicone flexible mould that I could safely get the shape out of. On the other hand, you can’t get much cheaper than Plaster of Paris, and since I didn’t need the wax sculpture anymore, I’d just melt it out.

Now, this process did present a problem. I would only have once chance for this. Such is the trade-off for inexpensive supplies.

When running a test. I noticed that wax floats in wet plaster, so I used some hot wax to adhere the the sculpture to the bottom of the container.

The plaster cured in a couple of hours and left me a nice hole to melt all the wax out.

Here’s my setup for reclaiming that wax. Usually the melt-out process is done at very high temperatures to ensure all the wax melts and evacuates completely, but if you superheat plaster it just becomes powder again, and my kitchen stove doesn’t get that hot anyway. So, I baked this contraption at 350 for about 5 hours. The whole house smelled like candles, but it worked.

This is the terrifying part. I’d been working on this for a couple days, and all I had to show for it was a complicated hole. It’s only one step away from completion, but I’d better make sure I know exactly how to do the next step.

This is the testing pit. It’s the beginning of tests 4, 5, and 6, actually. I didn’t show the original 3 resin tests because they were too depressing. I had followed the directions, but none of them hardened. The only one that even thickened a bit had twice the recommended catalyst. So this next test batch will get 3x and 4x the recommended dose, to see if that helps.

And to ensure accurate testing, I dripped wax into two of the moulds and burnt it back out. I wanted to see if the wax was going to present a problem.

Here you can finally see that color. I tried a lot of dyes and inks. This result was a mix of food coloring and artists’ ink. It worked beautifully.

What didn’t work was the uncoated test. The liquid resin absorbed into the thirsty plaster before it hardened, making a resin-impregnated plaster mix. It was impossible to get out of the mould cleanly.

The wax tests didn’t have that problem. It seems as though the liquid wax had already plugged all those tiny holes in the plaster, so the resin couldn’t get in. That’s great, because the real mould was already coated in wax!

This is how they came out of the mould. Nearly perfect. Apparently the secret is adding 4x the recommended catalyst amount. I’d read that extra catalyst could cause the product to crack in thicker pours, but that sounded kind of cool. I wouldn’t mind a few cracks in my fake mineral.

And the light test produced perfect results. I’m ready to do this.

I mixed way too much resin for the pour. But that was OK. I monitored what was left in the cup to see if it started cracking or when it hardened.

The extra resin was completely hardened in a half-day, but I gave the main project 24 hours to make sure. No cracks, and nothing wrong.

Then came the part where I got to use a chisel. Whack whack whack.

I can’t tell you how excited I was at this point. I had been worried about 2 possibilities: large gaping holes where resin didn’t get to, and unhardened resin. Neither one of those things showed up. I was beaming.

Then I just kept going. You can see in these pictures the ring of wax-colored plaster around the kryptonite. That kept everything from sticking. It was a very lucky accident.

Ta dah!

It’s just what I’ve always wanted… Death to Superman!

I took it inside and tried to determine the best place to put my LEDs. This thing has to glow afterall.

Once I figured out the placement, I drilled holes for the lights.

I couldn’t find my solder, so I just wired this together. It’s the guts from a mini-flashlight, with an extra LED attached. I carved out a spot for it to sit just under the surface of the back.

The flashlight also has a blinking setting, which Lex Luthor can use when he’s bicycling at night.

Test in the bathroom, where it’s dark. AWESOME!

…and I taped up the back so everything wouldn’t fall out. It’s not a perfect match, but you’re not supposed to see it anyway. The X is the flashlight button.

I forgot to show the chain, but it was super easy to attach. I just cut a link in half, drilled two holes in the kryptonite, and jammed the half chainlink in (with a bunch of superglue).

It feels good to help out the greatest criminal mind of our time.
See ya next week… unless you’re Superman.

UPDATE:

“It’s kryptonite, Superman. Little souvenir from the old home town. I spared no expense to make you feel right at home.”