The thing that keeps getting in my way is the cape. As a quick review, the cape is made up mainly of two parts. There is an outer shell, which is made out of some kind of flexible, rubber like fabric. It's made up of tons of tiny micro diamonds, or pyramids. Attached to that is a big piece of fabric. To keep things interesting, the fabric is ombre dyed, taking it from a bright crimson red at the bottom, to a deep red/brown near the top. There's really nothing simple about this cape. And somehow, the two separate layers are miraculously held together.
The good news is that I have a mold taken from a screen used cape, so the micro diamond pattern is on lock down.
From there on out, the challenges begin to pile up.
By my estimations, the outer shell must be made of either latex rubber or urethane.
My search for the right type of latex rubber took me in many directions. I ultimately found a product which dries relatively opaque, and does the service of NOT pulling back from the silicone mold when applied.
And that is a summary of the two main challenges when reverse engineering the outer shell. The material I'm looking for will be opaque when cured, will not pull away from the silicone, can be pigmented, and will be fairly light weight. Though that may sound like a reasonable list, it turns out it's really difficult to find something that satisfies all of those criteria. TRUST ME. It's not easy. I've spend many, many dollars experimenting with materials trying to get this right. It ulimately came down to a matter of compromise. It did not seem possible to find one product that did all of those things, so I had to chose which one I could live without.
And that frustrated me, and that kind of made me lose some traction on the project.
For the longest time, I was dead set on using latex. It's very inexpensive, is easy to work with, and with a little bit of experimentation, I was able to get a color that I was mostly satisfied with. It wasn't a perfect color, but to the untrained eye it would certainly pass.
BUT then I learned that when the latex I had selected, based on it's properties of opacity and tenacity, fades significantly when exposed to UV radiation for any length of time. Which means it's essentially useless.
Therefore, I switched my plan of attack to urethane.
Which also presented it's own series of challenges.
UNTIL...
And now we get to the heart of the story, which also serves as a lesson in tenacity. I was at Reynolds Advanced Materials, my local Smooth-On distributor, and was asking questions about different types of urethanes. I'm very familiar with many of them, not so much with others. I was talking to a gent there about their Vyta-Flex line. He informed me that it's like the newer version of their PMC line, which I have been using for years. Seeing as how vytaflex cures to be a near opaque, light amber color, I found this very interesting. PMC cures to be a dark, medium translucency amber, which is OK if I have some really strong pigments that I can use to block it out. Anyhow, I'm talking to the dude, and he mentions in passing that their Brush-On urethanes are the same as Vyta-Flex, but have cabosil mixed into it.
Hmmmmmmmmmmmm.
Brush-On was originally what I had pegged as the urethane to use on the cape, as it's the ONLY one that would lay flat on the silicone when I brush it on. ALL other urethanes I tested would bead up, or pull back from the silicone, rendering them useless. There was nothing I could do, no technique I had found, that would let me use any kind of urethane in the mold other than Brush-On.
Could it be that the secret differentiator was something as simple as cabosil? For reference, Cabosil is a super light, silica product that is basically a thickener, or thixotropic agent. I've talked about it elsewhere in this blog, but for different applications.
I picked up some vyta-flex and ran back to the workshop.
I mixed up a tiny batch, threw in some cabosil, and went to work on the mold. Sure as pooh, it worked!!! I was able to brush on vyta-vlex in VERY thin coats, and it would lay flat on the mold. This was miraculous.
I pulled out the old mermaid scale mold I used previously as a test bed for this project, and ran a couple dozen tests. Different urethanes, different percentages of cabosil, and finally found a formula that worked. I felt like I was back in business.
After running a couple of weeks worth of tests, I decided I had what I needed, and it was time to bust out Ye Olde Cape Mold and give it a shot on the real thing.
The mold has been crated up for a couple of years now, ever since I moved back to CA from Ohio, now that I think about it. As I was clearing out the shop and prepping for the uncrating, I became terrified that the mold had somehow decayed during the time it had been crated. Or that the mold had been resting on some uneven surface for the past 2 years, and had gotten creased or distorted.
Here's the crate, brought out from behind the previous locations of some supply shelves.
Fortunately, my foresight paid off. When I boxed up the mold in Ohio, I brushed in a few layers of latex to help protect the silicone. I was also smart enough to lay some butcher paper on top of it to keep the cardboard boxes from dinging it up. Long story short, the mold was completely undamaged by it's long term storage.
Earlier I spoke about the micro-diamond pattern on the cape exterior. Here's a closeup of said diamonds.
With the mold back in action, I got to testing the urethane and cabosil mix on the cape mold. It works EVEN BETTER than it did on the mermaid scale mold. It was going down extremely thin, and after just a couple of coats, it was completely opaque.
Even better, once I pulled it off the mold, it was extremely light and flexible. I must confess I was completely surprised by how light and soft the hand was on it. Everything is looking really good.
Back at the mermaid scales, I was testing some techniques for getting fabric to stick to the outer layer. I ended up just rolling on another thin layer of urethane and cabosil mixture, and then laying the fabric down on top of that. Worked like a charm.
The long pole in the tent from here on out is really the color. It's very important to get this right, or as close as I am capable. I set up a series of tests to try to determine the right recipe for pigmentation. I have a number of different pigments from a variety of companies. My hope is that a combination of them will get me the right results.
I started with a little scoop of sil-paks CU Pigment in each of my test cups. Sil-Pak's stuff is great because it really impregnates the urethane and makes it opaque. It serves as a good base for adding in other pigments.
From there it was just a matter of mixing in other colors. I added some UVO pigments, some so-strong tints, some douglas and sturgess pigments, and anything else I could get my hands on.
Then I just scooped a little bit out and added it to the cape.
Sadly, none of the colors really ended up being what I needed, but I learned a lot about how the colors interact when mixed. I think I've also noticed that the colors change non-trivially once the urethane is cured. For example, sometimes a color with a very bold brown tint will turn out to be completely red once cured. This makes mixing the perfect color very difficult, but I feel confident that with another six to eight years of experimentation, I will get there.
Hah just kidding!
So yeah, work continues. And honestly, I have to say this has been one of the most fun and fulfilling projects I have ever taken on. I have learned SOOOOOO much from this project, have met some great people, and have gained knowledge of so many new products and vendors.
One of the most recent things I did was an adhesive test. I was operating under the assumption that there might be an adhesive out there that I could use to join the outer shell to the inner shell. The reason I'm looking for this is because the process of attaching the two via a coat of urethane is problematic. Too thin, and they won't hold. Too thick, and you'll get bleed through. Basically, wet spots. I have already tested and dismissed a number of adhesives, but found a few more that I hadn't tried before. The basic problem is that the adhesive is either too strong and as a result corrodes the urethane, or it's too weak and won't stick at all.
Sadly, all of the candidates on this round of testing fell into one of those categories. As mentioned earlier, I am currently set on using a layer of urethane to join them, but I still hope that a magic adhesive will make itself known.
Hopefully some more updates will follow soon, and the cape will get closer and closer as the days go by.
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