(1964-65) Blank Pattern - RB-5335, INCO

Coin Details

Description

INCO experimental quarter-sized blank planchet RB-5335, one of several closely spaced compositions in the heart of the RB-53xx test series. The tight numerical clustering in this range — RB-5320 through RB-5350 with entries at nearly every five-unit interval — indicates that INCO's researchers had identified a particularly promising composition space and were conducting detailed parametric studies to find the optimal formulation within it. This is a hallmark of systematic industrial metallurgy: broad screening narrows the field to a few promising alloy families, then intensive investigation within each family identifies the specific composition that best balances all requirements. For RB-5335, the relevant requirements included matching the electromagnetic properties of 90% silver, achieving a visually acceptable surface appearance, maintaining structural integrity of the clad bond under repeated mechanical stress, and using alloy components that INCO could supply in the enormous quantities needed for national coinage production. The blank's unadorned surface makes it a pure metallurgical specimen, free from any design-related variables that might complicate the assessment of the alloy's intrinsic properties.

Rarity Notes

R-7 to R-8. Very limited production for Treasury evaluation. Part of a closely spaced composition optimization series.

Cross References

RB-5335 (Robinson-Breen catalog). INCO experimental blank planchet series, quarter-sized, 1964-65.