Patent US1820994A successfully refreshed from Google Patents.
US1820994A
Expired / Lapsed
US
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Process of and apparatus for treating fibrous materials for pulping purposes
Assignee: Individual
•
Filing: 1929-06-22
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Granted: 1931-09-01
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Expires: 1949-06-22
Abstract
No abstract record available.
Inventors
- 👤 Wallin Johan Hugo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:15
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22
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) | 1934-08-31 | 1935-03-02 | 1935-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1938-08-31 | 1939-03-02 | 1939-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1942-08-31 | 1943-03-02 | 1943-09-01 | $7700.00 | Window Closed / Lapsed |