I think I remember reading that IM6 represented a big shift in how graphite blanks were made, but can't remember what was before IM6 and what the difference was.

Am I way off, or does anyone have this info?

Thanks,
Marc

There were many graphite already on the market before IM6, their characteristics were as the modulus went up the durability went down. IM6 was the first we used that was different. The modulus was better and so was the durability.
Not quite the correct terminology, but I think I got the point correct.

Nearly all blanks were made from the same graphite material prior to IM6. It was considered the standard for all fishing rod manufacturers. I believe it was a Narmco product. About 33 million modulus if I recall correctly. It's still in widespread use among rod manufacturers.

G. Loomis, Inc. introduced the first blanks made from Hercules IM6 about 1985 or so. Nothing changed as far as how the blanks were made, however.

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I had some old graphite Loomis blanks that were made around 82/83 time frame...Still have em!