Patent US2475981A successfully refreshed from Google Patents.
US2475981A
Expired / Lapsed
US
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Process for blackening copper and copper alloys
Assignee: Heatbath Corp
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Filing: 1946-08-01
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Granted: 1949-07-12
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Expires: 1966-08-01
Abstract
No abstract record available.
Inventors
- 👤 Newell Isaac Laird
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:00
CPC Classifications
C; C23; C23C; C23C22/00; C23C22/05; C23C22/60; C23C22/63
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
DE423464C
Cited
FR590876A
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US1650124A
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US1769852A
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US1890603A
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US1892548A
Cited
DE647566C
Cited
US1894539A
Cited
US2364993A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1952-07-11 | 1953-01-10 | 1953-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1956-07-11 | 1957-01-10 | 1957-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1960-07-11 | 1961-01-10 | 1961-07-12 | $7700.00 | Window Closed / Lapsed |