Well, I should say continues... since we've already made the first batch of about 1000 electronics. But we were facing a challenge getting the transparency of the plastic just right. See, it needs to be translucent enough to let the light through, yet not be able to see inside with the light off. That's part of the trick that makes it feel magical to use.
I'm pleased to report that after several more samples, we were able to get it right! It was also amazing to see the outpouring of support from Kickstarter backers. Initially I felt like it was being selfish to take the time to do this extra iteration, but the comments showed that the backers want the exact same thing as I do- to make the best product possible.
So how did we solve it? In a word- science. Before we get to transparency, let's talk about color. As anyone familiar with printing things knows, getting color right is extremely difficult. Yes, there's the Pantone Matching System, but upstream from that there's a whole series of monitor calibration and "soft proofing" stuff to deal with. Then when you actually print things, every paper and press has its own variables. The color books are a good guide but ultimately, the on-press adjustments and in-person press check are what's required to get things to be accurate.
I was familiar with this process through my experience printing on Tyvek, which is particularly difficult. Here's the process we went through to arrive at a green for example.
Then when it came time to get the color I wanted on fabric, there turned out to be a whole other Pantone system- with an accompanying (more expensive) book that has swatches printed on fabric. Here's the process for getting the gray I wanted in case you're curious.
When it comes to plastics, Pantone has yet another system with, you guessed it, an even more expensive set of color reference chips. But unless you're having the plastic custom formulated and both parties involved in the process have access to the complete set of plastic chips, costing thousands of dollars, it's really not of much use.
So what you're left with is a combination of printing color books and reference objects. However, it still doesn't help define transparency. In the end, this turns out to be largely trial and error, which isn't necessarily such a bad thing, as long as you know which variables are controlling the outcomes.
In the home stretch of defining the transparency, I had the factory make 5 "steps" of transparency... from fairly opaque to pretty transparent. The only problem? One was way too transparent and the other 4 were practically opaque. So I really dove in to try and figure out what factors were determining the changes in opacity.
Each sample was created using a combination of clear material and dye. But the "x-factor" turned out to be additives that affect diffusion. I could see this in the samples but couldn't put my finger on it until I had the recipes. Some of them just "popped" or the quality of the light was just "pure" or "etherial". But you can't really ask a factory to make the plastic as etherial as they can, can you?
By adding just the right amounts of just the right ingredients, the result still allows light to shine brightly through, spreading the light around inside the plastic. This creates more of an inner glow effect that's visible from the outside, rather than a light transmitting through it like you'd get with a flashlight.
Once we identified the inputs that we needed to adjust, we needed a way to measure the output. And this turned out to be lux- the measure of light emanating from an object.
And needed a way for both the factory and I to measure and compare the results so we didn't have to wait for samples to go back and forth.
What I arrived at was a light meter iPhone app in a blacked out room (aka studio bathroom). Using the production electronics and firmware, I set it on 5 blue lights and covered it with each of the samples I had. The app has you make a diffuser to place over the camera, and then uses that to measure the light that hits it. So I kept the camera/sensor a consistent distance away and noted the readings. They ranged from 7.9 LUX to 63 LUX passing through- and exactly matched my perceived amounts.
Then the factory created a set-up as well. Theirs consisted of a light meter they could put inside a box and connect to a phone by Bluetooth. Their set-up was scientifically superior to mine actually, but we weren't trying to measure absolute values or reproduce results- the only thing that mattered was comparing the relative differences between the samples. So each set-up worked great as long as it was internally consistent.
We agreed that my 3D printed sample had the best combination of transmission and diffusion- so that was the target and they matched it down to .03 LUX- indistinguishable by the human eye.
To recap, we found the recipe of what goes into the plastic to achieve different results, discovered that in addition to transparency, we needed to leverage diffusion, and found a way to match the light transmission to the original sample. Wheew!
The end result? It just looks cool when lights are in it! A seemingly simple effect, but the way the light behaves in the material is a subtle cue to your brain that draws you in. It looks interesting- like there's something different going on in there. And that's because there is.