US1714879A - Process for removing enamel - Google Patents

Process for removing enamel Download PDF

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Publication number
US1714879A
US1714879A US714482A US71448224A US1714879A US 1714879 A US1714879 A US 1714879A US 714482 A US714482 A US 714482A US 71448224 A US71448224 A US 71448224A US 1714879 A US1714879 A US 1714879A
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Prior art keywords
enamel
bath
article
metal
temperature
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US714482A
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Harry O Lang
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/28—Cleaning or pickling metallic material with solutions or molten salts with molten salts

Definitions

  • the invention relates to a process for removing non-vitreous enamel from metals, and is particularly applicable for the salvaging of articles having a defective coating, since, according to th1s process, the metal 1s the treatment and the articles can be re-enameled without further preparation.
  • the process is particularly applicable also for use in removing baked or air dried enamels which usually have an asphaltum base, although the process may also be used in removing the coatings having a pyroxylin base.
  • the enamel is removed-by subjecting the article to a boiling caustic solution, or it is immersed in molten caustic soda; but in each of" these processes there are many disadvantages, among which are the injurious effects of the caustic upon the metal base, and, when using the latter process, the excessive temperature to which the metal is subjected has a tendency to warp the metal out of shape.
  • the enameled metal article is immersed in a bath of a molten metal salt at a temperature high enough to liquify the enamel so that it will separate from the metallic article, and, being of lesser specific gravity than the bath, will rise'to the top thereof and as soon as exposed to the atmosphere will be destroyed by burning.
  • the temperature at which the bath is maintained dgpends upon the melting point of the ename 700 Fahrenheit up; but I have found that when utilizing the temperature of substantially 975 Fahrenheit, the removal of the enamel may be accomplished very quickly and this, therefore, appears to be a desirable temperature for commercial work.
  • the material used "for the bath preferably has a melting point below that of the enamel and should have a gravity greater than the enamel and less than the metallic base, so that the article when immersed will remain below the surface of the li uid until the action is complete. It is also esirable and may range from.
  • the metallic salt is laced ina suitahlepot or container and raised to the desired temperature at which the material is in the molten condition.
  • the enameled article is then immersed in the bath for a short period of time, whereupon the enamel separates from the metallic base, rises to the surface of. the liquid and is oxidized, thereby maintaining the bath free from any substantial amount of impurities.
  • the article is then withdrawn from the bath and preferably is quenched in water to dissolve the adhering salt.
  • the quenching bath consists of hot water so that on removal of the article therefrom the heat remaining in the metal will quickly evaporate the moisture and provide a dry surface that is immediately ready for reenameling without any further preparation.
  • Examiner 1 As an example of the process, it may be stated that by' maintaining the temperature of the salt bath at approximately 975 F. the time for removing a enamel is approximately one minute.
  • a rocess for removing non-vitreous enamel rom a metallic base consisting in immersing the enameled article in a bath of a molten material comprising principally an alkali metal salt of nitric or nitrous acids.
  • a rocess for removing non-vitreous enamel rom a metallic base consisting in immersing the enameled article in a bath of a molten material comprising principally an alkali nitrate and an alkali nitrite.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Description

252. cemeesmcus.
in no way in ured by Cross Reference Patented May 28,1929.
UNITED STATES PATENT OFFICE.
HARRY O. LANG, 01 PONTIAC, MICHIGAN.
PROCESS FOR REMOVING ENAMEL.
No Drawing.
The invention relates to a process for removing non-vitreous enamel from metals, and is particularly applicable for the salvaging of articles having a defective coating, since, according to th1s process, the metal 1s the treatment and the articles can be re-enameled without further preparation.
The process is particularly applicable also for use in removing baked or air dried enamels which usually have an asphaltum base, although the process may also be used in removing the coatings having a pyroxylin base. According to the present practice, the enamel is removed-by subjecting the article to a boiling caustic solution, or it is immersed in molten caustic soda; but in each of" these processes there are many disadvantages, among which are the injurious effects of the caustic upon the metal base, and, when using the latter process, the excessive temperature to which the metal is subjected has a tendency to warp the metal out of shape.
According to my improved process the enameled metal article is immersed in a bath of a molten metal salt at a temperature high enough to liquify the enamel so that it will separate from the metallic article, and, being of lesser specific gravity than the bath, will rise'to the top thereof and as soon as exposed to the atmosphere will be destroyed by burning. The temperature at which the bath is maintained dgpends upon the melting point of the ename 700 Fahrenheit up; but I have found that when utilizing the temperature of substantially 975 Fahrenheit, the removal of the enamel may be accomplished very quickly and this, therefore, appears to be a desirable temperature for commercial work.
The material used "for the bath preferably has a melting point below that of the enamel and should have a gravity greater than the enamel and less than the metallic base, so that the article when immersed will remain below the surface of the li uid until the action is complete. It is also esirable and may range from.
' Application filed May 19, 1924. Serial No. 714,482.
that the bath should have no chemical effect upon the metallic base. While there are a great many materials which might answer the above requirements, I have found that from a practical standpoint, considering the cost of the materials as well as their effectiveness in producing the desired results, that the following materials are entirely satisfactory: Sodium nitrate, potasslum nitrate, sodium mtrite, OIjJLX COIIIblIlflt-IOII df'afiy of said materials.-
"I'ii' carrying out the rocess the metallic salt is laced ina suitahlepot or container and raised to the desired temperature at which the material is in the molten condition. The enameled article is then immersed in the bath for a short period of time, whereupon the enamel separates from the metallic base, rises to the surface of. the liquid and is oxidized, thereby maintaining the bath free from any substantial amount of impurities. The article is then withdrawn from the bath and preferably is quenched in water to dissolve the adhering salt. Preferably the quenching bath consists of hot water so that on removal of the article therefrom the heat remaining in the metal will quickly evaporate the moisture and provide a dry surface that is immediately ready for reenameling without any further preparation.
Examiner 1 As an example of the process, it may be stated that by' maintaining the temperature of the salt bath at approximately 975 F. the time for removing a enamel is approximately one minute.
-l-Vhat I cIaim as my invention is:
1. A rocess for removing non-vitreous enamel rom a metallic base consisting in immersing the enameled article in a bath of a molten material comprising principally an alkali metal salt of nitric or nitrous acids.
2. A rocess for removing non-vitreous enamel rom a metallic base consisting in immersing the enameled article in a bath of a molten material comprising principally an alkali nitrate and an alkali nitrite. I
In testimony whereof I aflix my signature.
HARRY O. LANG.
four-coat baked
US714482A 1924-05-19 1924-05-19 Process for removing enamel Expired - Lifetime US1714879A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2421617A (en) * 1943-02-03 1947-06-03 Vickers Electrical Co Ltd Method of removing coatings from metallic conductors
US2504906A (en) * 1945-08-10 1950-04-18 Westinghouse Electric Corp Composite metal electric contact member
US2641559A (en) * 1948-09-08 1953-06-09 United States Steel Corp Method of cleaning and descaling ferrous articles and a bath therefor
US2678290A (en) * 1946-09-05 1954-05-11 Pottberg Rolfe Process of removing surface oxide films on metal
US2751317A (en) * 1950-06-03 1956-06-19 John A Orme Method of removing insulating coatings from wires
US2939209A (en) * 1958-05-01 1960-06-07 Horizons Inc Reconditioning of electric apparatus
US3000766A (en) * 1958-04-28 1961-09-19 Horizons Inc Metal cleaning process

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2421617A (en) * 1943-02-03 1947-06-03 Vickers Electrical Co Ltd Method of removing coatings from metallic conductors
US2504906A (en) * 1945-08-10 1950-04-18 Westinghouse Electric Corp Composite metal electric contact member
US2678290A (en) * 1946-09-05 1954-05-11 Pottberg Rolfe Process of removing surface oxide films on metal
US2641559A (en) * 1948-09-08 1953-06-09 United States Steel Corp Method of cleaning and descaling ferrous articles and a bath therefor
US2751317A (en) * 1950-06-03 1956-06-19 John A Orme Method of removing insulating coatings from wires
US3000766A (en) * 1958-04-28 1961-09-19 Horizons Inc Metal cleaning process
US2939209A (en) * 1958-05-01 1960-06-07 Horizons Inc Reconditioning of electric apparatus

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