The single strand fiber optic filament we carry are not straight, but rather have a curl associated with them. The degree of the curl varies on the diameter of the filament. The curl is in large part due to the manufacturing and shipping process. For the technical applications that utilize fiber optics, the curl is actually factored in to the attenuation equation. However, given that our quest aligns more with the esthetic applications and the filaments ability to transmit visible light, every so often I will have a customer ask how they can eliminate or remove the coil, as their fiber optic project requires a ‘straight’ fiber optic.
To be clear, please note – Depending on the diameter and ultimate length of your section of fiber optic filament, it is possible to ‘remove’ or more accurately, ‘relax’ some of the curl. However you will not be able to remove all of it. Also, the thicker filaments (1.5 – 3.0) are a bit more challenging as the curl is more ‘set’ in the filament due to it’s thickness.
That said: Here’s a technique that we’ve utilized with some success. While it’s not difficult, it is a bit putzy. It’s a technique we’ve used for lengths to about 6 feet.
- First – Cut the fiber into sections slightly longer than you’ll need. We add an additional 6 inches.
- Next, suspend (hang) the individual filaments. We hang them in a door frame using the blue painters tape holding the top. Sometimes we will roll the end of the strand of filament around a dowel or a plastic coat hanger, then securing it with the blue painters tape. The few inches of filament that is rolled onto the dowel will be discarded after you’re done with this process.
- Then on the bottom end of each strand you attach a weight. Not too heavy where it will pull the filaments out of the top ‘assembly’ What kind of a weight? That in part depends on the diameter filament your attempting to work with. For the thinner filaments (.25mm – 1.0mm) we’ve used everything from several large metal washers per strand to the larger fishing weights. We found that fishing weights work great on these diameters as they clamp right onto the filament. NOTE: Clamping or attaching a weight to the filament will usually damage the fiber at the location area of attachment, that’s why we cut them longer than we ultimately need.
- Once the fibers are hung, we then ‘encourage’ the filaments to ‘relax’ by using a heat gun or blow dryer. We’ve used both, and prefer the heat gun. You’ll want to start with it on a ‘low setting’. The heat gun we use has a digital display, so we’re able to see the specific temperature level — we use it in the 200-300 degree range. Slowly ‘blow’ or guide the heat over the filaments, without pausing too long in one area. Depending on the thickness of the filament, the length and the strength of the heat gun, you may want to gently hold the filament with your other hand to help prevent them from tangling into each other. What’s interesting is that you can actually see the filaments ‘relax’ as you slowly apply the heat. Again – don’t pause too long in one area.
- If possible, we let the filaments ‘hang’ in this configuration overnight, and apply another healthy dose of ‘heat’ the next day before we take them down.
(BTW: The next time we have a project that requires us to ‘relax the curl’ we will take photos of the steps we outline above and add them to this answer.)