We will be closed on November 25, 2021 and November 26, 2021 in observance of the Thanksgiving holiday. We will resume normal operations on November 29, 2021. Wishing you a safe and happy holiday from all your friends at SparkFun!
How to make faux neon signs with EL wire and rigid aquarium tubing
In 1898, William Ramsay and Morris Travers succeeded in isolating neon gas from the atmosphere. Their subsequent Geissler tube tests inadvertently created an entirely new lighting technology: neon lighting.
The neon lighting that we're most familiar with today, the neon tube sign, hasn't actually changed that much since it was first demonstrated in 1910. Despite being a century-old technology (!) the neon sign industry survives to this day! There may be alternative technologies like LEDs and flourescent lights, but nothing perfectly imitates the glow of neon.
That said, let's try.
Electroluminescent wire is often compared to neon because of its soft glow and serpentine shape, and while it does look somewhat like neon, it lacks some of the clunky charm. Neon tubes, being glass, require heavy mounting brackets and fancy wire boots, little details that give neon a distinctive look. Not to mention, most EL wire is relatively thin diameter when compared to neon tubes. One's first thought might be to insert EL wire into bent glass tubing, and if you have lampworking supplies, then why not give it a shot? But the rest of us who are chasing that neon aesthetic might need to resort to slightly cheaper and less hazardous options. Enter: Rigid Plastic Tubing.
You can buy rigid polycarbonate tubing at many pet supply shops for use in aquariums, it comes in a variety of diameters and is optically clear. At first glance, this tubing really does look like glass. However, polycarbonate has a lot of advantages over glass: it's not fragile, it's inexpensive to buy and ship, and it has a much lower melting point, which means we can bend it with a heat gun!
If you've never bent tubing before, it can be a challenge. On making a sharp bend, the tube will want to collapse flat, and there are a variety of ways for dealing with this. The first is the method that glass workers use: As you're making the bend, blow into the closed tube to create pressure in the bend, which prevents the walls from collapsing. This actually works fairly well with the plastic tubing! I've also seen people bend plastic tubing by inserting a length of silicone tubing inside of it, which will resist the heat during bending and is flexible enough to be pulled back out after the bend is made. Check out aquarium forums for good resources on bending rigid plastic tubing.
The method that I eventually came up with was to insert the EL wire before bending the tubing, as it can be hard to push it through tight bends after the fact. Then I heat one end of the tubing and twist it off, trapping the EL wire and sealing the end of the tube. Next, I make my bends by slowly heating the site of the bend over an upturned heat gun and blowing gently into the tube while bending. Careful not to heat the plastic too much, or else bubbles will form! Below is a time lapse of my first attempt at making a sign:
The bending went pretty well, but I ran out of tubing... so I ended up cutting the Yen sign off and keeping it because it looked the best. The next step in making it look like neon was to black out the portions of the tube that aren't supposed to be seen. Because neon tubing is one continuous light emitter (much like EL wire) and because the process of evacuating, charging and sealing a glass tube is expensive and difficult, a neon sign is often made of as few lengths of tubing as possible. This leads to parts of the tubing passing behind or between the letters or active shapes, which need to be blacked out so they don't muddle the overall appearance. I blacked my "neon tubes" with a black Sharpie paint marker.
Finally, I capped the ends with thick heat-shrink tubing to emulate the look of electrode end-caps. Once the EL wire was hooked up, this is what it looked like:
I think it's pretty convincing, but in the dark there's really no sense that the plastic tubing is there at all, and because the EL wire is strung loosely, the shape looks a little wavy. What we need is a diffuser. Luckily, I may have a solution! Polycarbonate is soluble in acetone, so by filling the tubing with acetone and shaking it around a bit, we should be able to dissolve a portion of the inner wall and redeposit it. This will give the powdery white appearance of phosphor-coated glass. Unfortunately, the acetone will also attack the PVC jacket on the EL wire so the redeposited polycarbonate will be tinted the color of your EL wire. You may be able to avoid this by treating the tubing before inserting the EL wire and bending it, but you'll likely lose a portion of the frosting in the bends, as the heat will polish the inner wall down a bit. After a pretty rough acetone treatment, the sign lost a little of its daylight charm, but it looks much better in the dark! I think if you take a little more care in the application, the acetone frosting method could work quite well!
I'll keep working on this because I have a few projects that I think would look really nice with some "neon" signage. If you have any questions, ask me in the comments! If you've done something like this before, I'd love to see it!