The answer is NO! However, I have no real proof, so....
This summer I am having a chemistry professor at a university conduct a small study for me. I have personally bought from 4 vendors and will give these IET's to him for test. He is going to test them for denier (thickness/invisibility) color, and elasticity (Stretchiness) and rebound to original size.
I will post the results on MagicJoint but want anyone on Magic Café to take part if they wish. I am also going to give anyone an opportunity to send me 25 feet of "their" IET for the test.
I have also decided not to mention which companies performed poorly, just praise the companies and endorse the companies that perform good.

Finally, after talking to the professor, there may be certain issues with this from the get go... Every batch of elastic/spandex could be somewhat different. For example, have you have bought the same material for something and the color was a little off? This same issue might/does occur in IET, however, the quality of what I either bought, or was given will be what is tested and the thought is that is what will be sold to the public the majority of time.

With all this said if anyone has any other suggestion or comments please post, and I look forward to this testing.

Also if any owner/ person would like to add their IET and I have not bought it, just PM me and I will give you my address to send me a sample. I just ask for 25 feet, so all the test can be performed equally.

The real test is how does it work for the magic?

You are absolutely right! Not only how it works for magic, but which magic you perform. Stage magic doesn't have to be as invisible as close up, and so on...
I am posting two items I have been working on for several years on magic joint, under videos, (when I figure out how). It is close-up table hopping type. I will be testing which ever IET works the best in Florida, when I take vacation in July. As it goes, I know what works good in my basement, but not in real life. I will not only test what I have the most of, but also the universities findings, to find out if they are either spot on or not.

@magic_son:

I live in Florida myself and so far Legacy IET has held up the best for me; if that contributes to your results in any way...

Email me your address I'll send in Legacy for this Test I'm not scared

I agree testing color and what it is actually made of holds no point
but which one works better for the application you are using it for in your magic....
Finding out if it is spandex, lycra, elastin won't help the magicians out with there decision on which to buy.

I also live in Florida let me know when your down by Tampa
Legacy holds up great in this sauna of a state

When Finn Jon was working at Raymond's Review bar (lots of exotic female dancers) he would get long hairs from the ladies.

That's a good point about temperature sebashtion, I would think (but do not know) that in time, IET would break down similar to rubber bands, if you didn't keep it in an air tight, out of the sun, place and maybe even then. We don't care what it is made out of we are looking for performance, but it is hard to compare unless we have some perimeters. That is where the strength (amount it will hold) the denier (how easy to see), and rebound quaility come into play. If there is any other suggestions about testing, let me know. I am sending you my address now (PM)

Mr. Biro, Dad made me read the Al Baker book. I found he also worked with IT, where he used hair. I never met him, but in his writting, he seemed brillant.

As promised, the results are at magic joint if anyone is interested.

In your last paragraph, I was a bit confused, but you seem to say that John LeClair used more of an IET than IT re: his "Whose Afraid of Invisible Thread". This is not correct, John used a standard IT harvested from tights. I used to get IT using Jon's method. The effects and hook-up on Jon's DVD were designed to work with standard IT (the IT that used to be supplied with the VHS & DVD was not IET, but IT).

I tried recently to harvest IT from tights, but had to use a different brand (Jon's suggested brand was no longer in production), and sadly, IT was not harvestable from them. Perhaps there are other brands that may still be used.

Ooh, I never thought of that before. I'm a total newb when it comes to IT/IET... Are there specific recommendations on how to store the loops, IT/IET, reels, etc?

Best way to store them is in a sandwich type bag in a dark cupboard and they will last years.