The claim that Leistner's hand-polishing outperformed machine methods is echoed by a second independent source but still lacks a Tier 1–2 primary

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Beyond the Powerhouse Museum's claim that Achim Leistner's "fabrication method has been found to be superior to any purely machine-based method," a second independent, named source makes essentially the same claim. Jonathon Keats, in Wired (2011), writes that Leistner "works by hand because he believes — and the most advanced computer imaging has confirmed — that no machine can match his touch." This is genuine corroboration in the sense that a second on-the-record source reports the same superiority claim rather than merely repeating the museum's wording — see claim-leistner-atomic-feeling-corroborated-beyond-powerhouse-museum for the broader narrative this sits inside.

It is still not enough to clear the sourcing floor for what this actually is: a specific technical-mechanism claim (that hand-lapping measurably outperforms machine polishing, and by what metric), which requires a Tier 1–2 primary. Both sources on record are Tier 3 magazine/museum prose, and neither cites the "advanced computer imaging" study directly. No Tier 1–2 source recording this comparison has been located as of this promotion. The claim stays [unverified-mechanism — needs primary], tracked at question-verify-leistner-atomic-feeling-superior-to-machines. A directly comparable Tier-1 quantitative record — a later, non-Leistner repolish that measurably out-rounded his original spheres — cuts the other way; see claim-ptb-repolish-out-rounded-leistners-original-avogadro-spheres.