Patent US2521580A successfully refreshed from Google Patents.
US2521580A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coloring stainless steel
Assignee: Armco Inc
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Filing: 1948-05-05
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Granted: 1950-09-05
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Expires: 1968-05-05
Abstract
No abstract record available.
Inventors
- 👤 Regina L Hornak
- 👤 John J Halbig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:20
CPC Classifications
C; C23; C23C; C23C22/00; C23C22/05; C23C22/06; C23C22/07; C23C22/08
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
88 words
IN COLORING STAINLESS STEEL ESSENTIALLY CONTAINING ABOUT 10% TO 35% CHROMIUM, THE ART OF PRODUCTING A THIN, ADHERENT SURFACE FILM THEREON RANGING IN COLOR FROM YELLOW TO PURPLE, WHICH COMPRISES IMMERSING THE STEEL IN A SOLUTION ESSENTIALLY CONSISTING OF ABOUT 0.25% UP TO ABOUT 5% PHOSPHORIC ACID BY WEIGHT AND THE REMAINDER SUBSTANTIALLY ALL WATER, WITH SAID SOLUTION AT APPROXIMATELY BOILING TEMPERATURE, AND EMPLOYING A PERIOD OF IMMERSION RANGING UPWARD FROM ABOUT 20 MINUTES TIME TO MORE THAN ABOUT 20 HOURS DEPENDING UPON THE COLOR AND HUE DESIRED.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-09-04 | 1954-03-06 | 1954-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-09-04 | 1958-03-06 | 1958-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-09-04 | 1962-03-06 | 1962-09-05 | $7700.00 | Window Closed / Lapsed |