Originally Posted by JR SPEY
I think you were right when you mentioned that maybe you weren't making your point clear early on. I agree that some materials are not the diameter that is stated on the spool. Also, many materials test out at a higher breaking strength than what is listed on the spool (and a few test out with less strength.) This has bothered the Europeans enough that there is now a testing procedure available that puts the EFFTA approval on materials that past the test for correct diameter and strength. Perhaps that's what will happen eventually in this country. For someone who consistently gets high readings on most materials he/she tests I often think that they may have a defective micrometer, but if most of the materials you check are accurate or very close and others are off, I would say that either the manufacturer is careless about which label is put on with each spool or is deliberately mislabeling its product. Truthfully, I don't really know why a company would want to do this as there really doesn't seem to be any marketing advantage to it, other than perhaps coming off as having a stronger material to those fishers who don't check the diameter. Anyway, I'm rambling. I'm not sure what specifically can be done about it other than the rather costly prospect of having some independent testing concern test the product before it goes to market. Thank you, though, for clearing up the intent of your initial post.
Regarding break strength, one prominant fly shop owner told me that's the property that he see the most variation in. And good for the europeans! We need more of that kind of activity over here. On the micrometer, while it is a precision measuring instrument, I believe it is very hard for it to be inaccurate. If you get a zero reading fully closed, and if it checks out against some standard of known diameter then its accurate. More to the story of my original thread, and a good example of micrometer accuracy, is that the Mfgr. of the 0.011" dia tippet that should have been 0.010" did get back to me. They were quite concerned and sent me a spool they said would be truly 0.010" free of charge. Sure enough, it measured exactly 0.010" with my micrometer. Right now I'm quite pleased with them once more. It does look to me as if mfgrs may be oversizing for just the reason you give - ie, it makes them look better in the strength department. They've probably determined that few ever bother to check the diameter of the tippet they buy, and a great many others don't care. Judging from the activity generated by this thread it would seem they are right. In my case I got so comfortable with the aforementioned mfgr that truthfully I stopped checking the diameter each time I bought a spool. But the over sized spool I bought seemed to be over sized when I first started to use it and this prompted me to check it out.