US1556796A - Process of etching glass or the like - Google Patents

Description

, Patented Oct. 13, 1925.

UNITED STATES.

PATENT OFFICE CLABKE 0., MINTER, OF NEW YORK, N. Y.

PROCESS OF 'ETCHING GLASS OR THE LIKE.

No Drawing. Application filedliay' 27:,- 1921, Serial No. 473,010. Renewed March 2, 1925.

To all'whiom it may concern:

Be it known that I, CLARKE C. MINTER, a citizen of the United States, residing at New York, in the wunty of New York and State of New York, have invented a certain new and useful Process ofEtching Glass or the like, of which the following is a specification.

My invention relates to the etching of glass or the like, and particularly to the etching of comparatively large portions of the surfaces of articles an objects made of glass or the like, such for-example, as window glass, electric light bulbs, lamp shades,

lig t transmitted therethrough, and chinaware and porcelain articles to produce or namental surface effects.

' As is well known, the agent most frequently used in the etching of glass is hydrofluoric acid, a comparatively expensive agent and one inthe use of which extreme care and precaution are necessary to be observed to avoid injury to the o erator. The care and precaution require further increase the cost of the etching operation, the process when carried on commercially and to any substantial extent usually being performed in a specially-prepared chamber.

I Etching has also heretofore been done by the forcible projection of sand or like abrading material against the surface to be etched, and this process has the advantage over etching by hydrofluoric acid in the cheapness of the material used and the safety attending its use, but has the disadvantage that special apparatus andmachinery are required to produce the blast of the abrading material.

My invention-has, among its objects, to

provide a process of etching eliminating the disadvantages of the customary processes heretofore mentioned, by the use of an etching agent or material of comparatively little 1produce ornamental effects or diffusion of ditions of temperature of the glass or like obj eot to be etched and of the etching agent, a normal or an acid carbonate of an alkali metal may be used as an effective etching agent.

I preferably employ sodium carbonate although I have also 'found a mixture of sodium and potassium carbonate an effective agent, the addition of .the'potassium salt-although having the disadvantage of somewhat-increasing the cost over the use of. the sodium salt alone-having the advantage of permitting a lower temperature at which the etching is effective. The cominercial, as distinguished from the chemi cally pure salts mentioned, may be used.

The range of temperatures, so far as the heating of the carbonate is concerned, should include the fusion .point of the ,salt, and the heat need not extend appreciably above that point.

The process of etching can be performed either at some stage during the manufacture of the glass or other like object when the heat thenbeing utilized in such manufacture can be utilized for this process reheating the object after its manufacture, and in the later instance, the temperature need not be so high as to distort the object.

I have found that heating the object to be etched to approximately what is familiarly known in the arts as a dull red heat of glass is a preferable degree of heat, although not an essential degree as the heat may be varied above that temperature or below the same, the. etching being possible at as low a temperature of the glass as approximately 300 centigrade.

My invention may be carried out by any of the following illustrative processes:

1'. The glass or like object to be etched is or by heated in an open flame, into which the desired carbonate, for example sodium carbonate in finely divided particles or powder form, is injected at some point below the glass object.

Any suit-able apparatus may be used for injecting the sodium carbonate into the flame, such for example as an apparatus providing an air or other fluid pressure for blowing solid material in finely ivided particles. I have found an ordinary bottle of appropriate size partly filled with the powdered salt and with a tube extending below the surface of the salt within the bottle, and terminating outwardly in a nozzle, and

the bottle provided with a collapsible bulb for the creation of an air pressure upon the salt, sufficient for the purpose.

The sodium carbonate thus injected into the flame is itself heated b the flame to the required temperature an quickly carried upwardly into contact with the heated surface of the glass, and the particles of the salt attack the glass wherever they come into contact therewith.

In this case, it is to be observed that a single heating medium is utilized to heat boththe glass to be etched and the etching agent.

The etching action apparently involves a reaction between the sodium carbonate and the silica of the glass. with the production of a soluble silicate, sodium silicate, which is removed by washing the glass with water after the same has been cooled, and carbon dioxide which escapes as a gas. Other reactions may possibly be involved, but in any event, the surface of the glass or like article is pitted and roughened and the desired effect produced.

The powdered salt is applied in the manner stated to the surface of the article after its manufacture, in which case its temperature is raised to the required or desired degree, or duringsome stage of its manufacture when it is at the suitable temperature,

as, for example, between the blowing of theglass and the finishing of the article, or during the annealing of the same. The simplicity of the process renders it particularly applicable to the etching of the article during its process of manufacture, as indicated, and in the application of the process on a commercial scale, the apparatus for blowing the powdered etching agent upon the surface of the article may. be located in the line of travel of the article through the various stages of its manufacture.

2. A melt of the desired carbonate or mix- .ture of carbonates, for example, sodium car- Letters Patent is comprising heating the glass or the like to be etched, directing sodium carbonate in finely divided particles into contactv with the surface to be etched, cooling the article thus heated and washing its said surface.

4. The process of etching glass or the like comprising heating the glass or the like to be etched, heating an alkali salt of carbonic acid to atleast the fusion of said salt, and causing contact of said fused salt with the surface of said glass or the like to be etched.

5. The process of etching glass or the like comprising heating the glass or the like to be etched, heating an alkali salt of carbonic acid to at least the fusion of said salt, causing contact of said fused salt with the surface of said glass or the like to be etched,

thereafter cooling said article and washing its said surface.

6. The process of etchingglass or the like 7 i comprising heating the glass or the like to a vtemperature approximately 300 degrees centigrade or above, heating an alkali salt of carbonic acid to at least the fusion of said salt, andcausing contact of said fused salt with the surface of said glass or the like to be etched.

7. The process of etching glass or the like comprising heating the glass or the like to a temperature approximately 300 degrees centigrade or above, heating an alkali salt of carbonic acid to at least the fusion of said salt, causing contact of said fused salt with the surface'of said glass or the like to be etched, cooling the article thus treated and washing the said surface.

8. The process of etching glass or the like comprising heating the glass or the like to a temperature approximately 300 degrees centigrade or above, heating sodium carbonate to at least the fusion point of said salt, causing contact of said fused salt with the surface of said glass or the like .to be etched, coolin the article thus treated and washing its sald surface. g

9. The process of etching glass or the like comprising heating the glass or the like 'in' an open flame, and directing an alkali salt .of carbonic acid in finel divided particles into said flame into posltion to be carried upwardly thereby into contact with the surface to be etched.

10. The process of etching glass or the.

like comprising heating the glass or the like in an open flame,'and directing sodium carbonate in finely divided particles into said.

May, 1921. I

' CLARKE O. MINTER.