My tag-along question: Is there any way to tell if a tension hoop is brass or pot metal?

I bought a  pot-metal tension hoop (Prucha or AMB) over 10 years ago for my first (now long stalled) build. I think I swapped it into one of my banjos. But now I don't remember.

Sorry readers, somehow that photo of Earl snuck into my post. Not part of my question. Photo has already been explained to me, long ago.

Ken, there's a distinct difference in "tone" of brass v pot metal tension hoop if you hold each one of them up and rap on it with something. Brass hoops make a musical note. Pot metal makes a distinct metallic "twank".

I've never had a post 1987 Gibson tension hoop in my hands at the same time as a known sample from another banjo to do this test myself.

Old Hickory,

"Pot Metal" is the term often used to refer to components manufactured with a process that's typically referred to as "die casting". In die casting, molten metal is injected into a die to create the part. The process is used mostly for parts made of aluminum or zinc alloys.

The dies have round ejector pins that facilitate the removal of the part from the die. The ejector pins leave small, round, shallow indentations on the part. Those telltale indentations are evidence of the die casting process. Parts made in a die also have "draft", which is a tapered surface that is also intended to facilitate removal from the die. The taper is another telltale indication that a part has been manufactured using a die.

It's quite uncommon to find die cast parts made with brass. If you can determine that a part has been made using the die casting process, it's most likely that it's aluminum or zinc alloy.

The flanges and tension hoops of vintage Gold Star banjos (manufactured by Tokai, accounting for 90% of the total) were made of die-cast brass. While zinc has a melting point of 790°F, brass melts at 1,600°F; consequently, even a single casting run causes minute cracks in the die-cast mold. As a result, tension hoops require lathe machining on all four sides. In contrast, zinc die-cast molds do not develop such cracks, meaning the remaining production steps involve only minor deburring, buffing, and plating. Brass flanges also require machining across nearly their entire surface, leading to an estimated per-unit cost several times higher than that of zinc. Regarding mechanical properties, zinc parts are prone to deformation and deterioration, whereas brass parts are not. Tension hoops can be manufactured relatively easily by brazing and machining brass bar stock. Gibson’s management consistently prioritized cost reduction in banjo production. Compared to the ball-bearing tone rings of the early 1920s, the shift to sand-cast tone rings and the 1929 transition to zinc die-cast components drastically reduced the number of parts as well as the labor required for machining and assembly. Based on my own experience, I can state with certainty that the adoption of the three-ply rim was also driven by the goal of cutting costs.

Does a brass tension hoop (and flange, for that matter) contribute to a brighter tone? I suspect that may be the case with my Ome, and I note that Stellings have brass hoops and flanges.

My '86 StewMac "Vintage" kit has bell-bronze ring,hoop and flange.
I feel it has more sustain than my zamac hoops and flanges.
I prefer the sound of the pot metal hoop and flange.
Words are tough to describe sound,but I like the drier tone of the pot metal banjos.
Jimmy Cox used aluminum mixed with pot metal,I believe.Stronger.

Just last week I switched from a brass to pot metal tension hoop. I didn't know what at first I had so I just filed away a piece of the plating in a location where it won't be noticed.

Once I had both hoops in hand I tested their sound by hitting them. They both had some ringing overtones but the brass hoop also had a lower pitched distinguishable note and vibrated longer than the pot metal hoop.

Once on the banjo the pot metal hoop makes the banjo sound like it has less sustain, fewer overtones, and maybe a slightly brighter sound.

The only pot metal tension hoops I have seen have been on prewar instruments like Ludwig, and the like. I have worked on a number here where the hoops have broken.

Did not Gibson source many of their metal parts (in the modern era) from either Stew-Mac or First Quality?

Since the 1960's I don't recall ever seeing a tension hoop in other than brass for many years, as it was superior in long-term use to pot metal, which although cheaper could flare out and break.

So my reckoning is that from the 1960's on, Gibson used brass tension hoops and probably never used a pot metal hoop at all...

StewMac started listing "die-cast" for their flanges in the 80s.Not sure if this included hoops.I should look through my old catalogues.
I also believe Gibson was using StewMac pieces back then.