This is sort of a review and a comparison between professional Invisible Elastic Thread (from now on referred to as "IET") and What I could come up with going to Joann's. In this case, I have bought Yegal's 100 ft. spool of IET. I would like to say that I was not inclined one bit at going from my homemade investment of $1.75 all the way to $15.00 but can see why there is such a price hike for what you get.
The "Joann's Special" A.K.A. What I came up with:
At Joann's, they sell specialty threads of all kinds. One of which is what they call "Elastic Thread". This thread is basically a clear elastic cord that has been wrapped with black thread. Upon stripping this black thread and looking closely at the transparent elastic, one can see that the cord itself is comprised of several smaller threads of elastic (think of stripping regular IT, its that sort of format.). I then stripped this elastic down to a very thin fiber of elastic and tied a loop using "The Million Dollar Knot". I wore and used this loop for about a day, until it broke. To me, that was acceptable and although the thread was incredibly reflective, I really had no complaints. That is until Yegal's thread came in.
When I received Yegal's IET in the mail, I was excited, yet slightly skeptical of allegedly one of the best IETs that money could buy. I opened the package and tied a loop in about 5 seconds. wow, that's invisible. The thread is thicker than what I was using but is somehow incredibly more invisible. I tried the loop under florescent light and on light surfaces, everywhere. Nothing. It was only until I held the stretched loop over a dead-white surface under florescent lighting did I see a simple line between my hands. No glimmer, and very little reflective property.
The thread I got at Joann's I would recommend for beginners, since it is incredibly sensitive to lighting and would do well teaching magicians to properly maximize their environment. The thread is also incredibly forgiving and elastic, much more than Yegal's. On the other hand, Yegal's thread is less forgiving but is more invisible. I think if you lose your loops or are in a pinch and have to perform with loops, a trip to Joann's isn't out of the realm of possibility.