Seasoned black patina and hollerith tabulator: what they have in common

1. Step 1. Seasoned black patina — is part of — Cast-iron pan. Polymerized oil protects against rust and sticking.
2. Step 2. Cast-iron pan — is made of — Cast iron. Cast iron.
3. Step 3. Cast iron — is material for — Hollerith tabulator. The casing is cast iron.

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