pbcatchemup wrote:
What makes the latest glass rods better than the oldies? Specifically, what changes in glass fibers, resins, tapers or construction methods make them better?
Dusty linked to a worthwhile podcast discussion with Jim Bartschi of Scott Fly Rods. At 30:30 Bartschi states, "
where there's not a ton of innovation going on the material side, the way to create something new is to innovate with what's out there." By 1980 the major technologies for fiberglass fishing rod production were in place (see the table). US fiberglass fishing rod production then declined to near extinction by the early 90s. In the years since glass made a slow comeback, but there were no major leaps in materials or methods. However, as Jim Bartschi states often in the podcast, rod design and manufacturing are always being refined, with continuous tweaks and improvements (discussion below the table). The podcast is definitely worth a listen.
Notable Glass Tech Milestones - Materials Version
- 1930s - glass fiber production was developed by Owens-Illinois (Owens-Corning PDF historic document - see page 4 of the document).
- 1935 - Borosilicate glass fibers (E-glass) and glass fiber reinforced plastics were developed (see page 6 of the PDF document).
- 1945/1946 - tubular fiberglass fishing rods were first marketed. Early glass fiber composites were based on phenol/formaldehyde (phenolic) and urea/formaldehyde resins. With time the market moved to the NARMCO production method of wrapping a fiberglass cloth impregnated with a binding resin (aka, pre-preg) around a steel mandrel followed by heat curing. Several companies developed high pressure autoclave curing to reduce voids in the phenolic resin (for example; Pacific Laminates, Phillipson, Grizzly/Fenwick, Conolon).
- 1947 - Lynco Grinding Company began commercial mandrel production (everyone bought their mandrels from Lynco).
- Early 60s - Phillipson begins building rods with 3M Scotchply pre-preg (uni-directional fiberglass with epoxy resins - Johnson & Johnson, Fiberglass Fly Rods, 1996). 3M markets Scotchply Type XP-231 "designed specifically for fishing rod manufacture" (3M sales flyer, 1967).
- Early 60s - S-glass was developed for military use. In 1967/68 S2-glass (the 'commercial' version of S-glass) was marketed by Owens-Corning (see Kinsella et. al., Mechanical Properties of Polymeric Composites Reinforced with High Strength Glass Fibers). For 50 years S2-glass has been the highest specification glass fiber on the market.
- 1965 - Fenwick tip over butt ferrule was patented (US Patent 3,186,122).
- 1968 - Jon Tarantino's spigot ferrule was patented (US Patent 3,554,590).
- 1973 - Fenwick and Shakespeare marketed graphite (the various graphite flavors aren't significant here, nor are boron or Carrot Stix).
- 1977 - S2-glass fishing rods are marketed. Fenwick offered Fenglass, a composite with S2-glass axial fibers and E-glass hoop fibers. In 1979 Sage initially sold their S2-glass rods alongside their graphite models. Likewise Lamiglas marketed their S2-glass rods in 1979. Berkley used S2-glass in their Specialist rods (anyone have a catalog for these?). With the exception of the Fenglass Lunkerstix, the market ignored S2-glass in favor of graphite.
On the modern fishing rod market there are two flavors of
glass fiber, traditional E-glass and S2-glass. S2-glass is marketed in the US as S2-glass or Zentron (a tradename held by
AGY) and as
T-glass in Japan. The binding resin is invariably an epoxy, which allows heat curing
without high pressure autoclaves. Epoxy chemistry has long been a mature field. While there are many epoxy choices available to a rod designer, the basic effect is the same - the epoxy efficiently holds the fibers in place. A third, very proprietary component is rarely mentioned. Sizing chemicals (see
Kinsella et. al., section 3) are applied to the raw glass fibers to improve handling and resin adhesion. The phrase "new resin systems" refers to variations of the same basic chemistries.
Aeronautics, automotive, wind power, and military uses drive the market for stronger, lighter composites. With fiberglass this is done by improving the fiber/resin bond and increasing the amount of fiber with respect to the resin. Increasing the amount of fiber also increases the composite's
elastic modulus. Skipping the math for now, a higher modulus composite allows the rod designer to obtain a relatively slender blank, or a thinner walled blank, or a combination of both. For instance, the classic Scotchply XP231 contained 47% fiber volume in the final composite. The
Zentron product description indicates fiber volumes of 60%, leading to a 30% modulus increase simply by having a more efficient composite. This 30% increase was not a sudden leap of technology, but more like a bank account earning 0.5% per year. Forty five years of small improvements add up.
Modern rod rolling equipment is designed to handle thin graphite pre-preg materials. I measured two Phillipson six weight Epoxite blanks and the butt section walls were ~0.035". Scotchply XP231 yielded a fiberglass 'ply' 0.009" thick, meaning my rods were produced with only four wraps of material around the mandrel. Glass prepreg now comes
as thin as 0.004", which would translate to 9-10 wraps of material for the same wall thickness. Thinner prepreg allows allows the rod designer more flexibility in designing those thinner walled blanks.
On the
Swift Fly Fishing website (Epic rods) there is an interesting statement, "
Materials may come and go, but fly rods are all about tapers." The materials market has provided years of incremental improvements. In the aggregate these allow a rod designer to pursue new tapers. Whether these tapers are better than, or simply different from, the classics of the 70s is a whole different discussion.
Tom