US2174887A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impregnation of porous materials
Assignee: National Carbon Co Inc
•
Filing: 1936-09-23
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Granted: 1939-10-03
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Expires: 1956-09-23
Abstract
No abstract record available.
Inventors
- 👤 Edwin F Kiefer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:46
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B41/45; C04B41/46; C04B41/48; C04B41/488; C04B41/80; C04B41/81; C04B41/82; C04B41/83; Y; Y10; Y10T; Y10T428/00; Y10T428/30
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1942-10-02 | 1943-04-03 | 1943-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1946-10-02 | 1947-04-03 | 1947-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1950-10-02 | 1951-04-03 | 1951-10-03 | $7700.00 | Window Closed / Lapsed |