US2297981A - Method of frosting glass articles - Google Patents

Description

Oct. 6, 1942. M. PIPKIN METHOD OF FROSTING GLASS ARTICLES Filed April 7, 1959 'Invenbof: v Marvin PipKin, y W

His

c?) Attorney.

Patented Oct- 6, 1942 METHOD OF FROSTING GLASS ARTICLES Marvin Pipkin, Cleveland Heights, Ohio, assignor to General Electric Company,

New York a corporation of Application April 7, 1939, Serial No. 266,601

My invention relates in general to atmetnod of frosting the surface of glass articles, and more particularly to a method of frosting the interior surface of electric lamp bulbs. Still more particularly, my invention relates to a glass article having a frosted surface of distinctive structure.

One object of my invention is to provide an electric incandescent lamp bulb with a relatively rough inside frosted surface which will diffuse the light rays from the filament to such an extent as to eliminate images of the so prevent the occurrence of a bright spot of light within the bulb.

Another object of my invention is to provide a novel method for the production of 'a relatively heavy frost of distinctive structure on the surface of glass articles.

Still another object of my invention is to provide a reflecting electric incandescent lamp of distinctive appearance and structure in which all sharp images of the lighted filament, as well as the intense mirror effect of the reflecting coating, are eliminated.

Further objects and advantages of my invention will appear from the following detailed description of species thereof and from the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of a lamp bulb illustrating a step in the production of the inner frosted surface according to my invention: Fig. 2 is an elevation partly in section of the completed lamp bulb comprising my invention; Fig. 3 is an elevation of a modification of the invention in which a portion of the inner bulb surface is covered with a reflecting coating; and Fig. 4 is a fragmentary sectional view, on an enlarged scale, of the bowl portion of the bulb shown in Fig. 2, illustrating the structure of the heavy frosted surface comprising my invention.

Referring to the drawing, a glass bulb such as is employed for electric incandescent lamps is shown at i8. According to the inv ration, the entire inner surface of the bulb, or only a portion thereof, is provided with a rough or heavy frost of distinctive structure, as indicated at H in Fig. 2. This heavy inner frost is formed by the method comprising my invention, as described hereinafter.

-As showninE-igLthebulb llisfirstfilled with a quantity material such as which varies. and the bulb position. but preferably mercially known as No.

lead bird shot t2, the size of placed in an upri t finer than that com- A sufllcient should not be shot.

filament and of small globular acid-resistin The shot may be of any desired size,

- only the bowl portion an etching solution in with sufficient lead shot the rays of light emanatin from a amount of shot is inserted to cover the ixmer surface area to be provided with the heavy frost.

according to the invention. In the particular form illustrated in the drawing, the bulb is filled to cover approximately the lower half or bowl only of the bulbous portion of the bulb. An etching solution that will etch the glass, such acid, is then poured into the bulb so as to just cover the lead shot II. This treating solution is allowed to act on the glass of the bulb for a period of from five to ten minutes without any movement or disturbance of the bulb or its contents, so that the lead shot I! is maintained in fixed relation to the inner bulb surface throughout the etching operation. The etching solution and the lead shot I: are then poured out simultaneously and the bulb washed out.

As shown in Figs; 2 and i, the above-described etching process produces a frosted surface of distinctive structure consisting of a myriad of round peaks or protuberances I3 all separated by relatively large, rounded and interconnected valleys or depressions. With such an etched surface,

filament 'located within the bulbous portion of the bulb are diiiusedtosuchanextentastoeliminate any sharp filament images or bright spots within the bulb.

In the bulb illustrated in Figs. 1 and 2, in which is provided with the frosted inner surface according to the invention, it is desirable to provide the remainder of the. inner bulb surface with a relatively light frost or etch ll (Fig. 2), such as is employed at present on conventional electric incandescent lamps. This secondary frosting operation is preferably carried out by first covering the heavy frosted surface li with a suitable acid-resistin medium, such as parafline wax, and then treating the re-.- maining exposed inner surface of the bulb with the manner customary for the production of conventional inside frosted lamp bulbs. The wait covering on the heavy frostedsurface ii isthenremovedinanysuitable way, such as by dissolving- In the modification shown in Fig-3, the lamp bulb there shown is the same as that shown in Fig. 2 with the exception that the bowl portion, i. e.. the portion provided with the heavy inside frosted surface II, is covered with an inner reflecting coating l5 of aluminum or silver, or any other suitable reflecting material. The result is a reflecting surface having a myriad of relatively small depressions or dimples l6 therein readily as 30 per cent hydrofluoric 1 visible to the eye and presenting a pebbled appearance. Such a reflecting surface gives diffusion to the light rays emanating from the filament, thus eliminating all sharp images of the filament. In addition, such a reflecting surface l5 eliminates the intense mirror eil'ect normally characteristic of a bulb provided'with a reflecting coating on a plain glass surface.

While I have described my invention in connection with the production of interiorly frosted electric incandescent lamp bulbs, it is obvious that it may be applied equally as well to the outer surface of such bulbs or to the frosting of flat glass surfaces.

What I claim as new and desire tosecure by 15 Letters Patent if the United States is:

A method for the production of inside frosted bulbs which" comprises partly filling said bull: with a quantity of loose but closely packed relatively small globules of a substantially acidresisting material. treating the inner bulb surface covered by said acid-resting material with an etching solution while maintaining said acidresisting material in fixed relation to said surface, removing said solution and said acid-resisting material from said bulb, washing the treated inner surface of said bulb and entirely covering the said treated surface with a layer of acidresisting material. treating the remainder of said inner bulb surface with an etching solution, and

removing said layer of acid-resisting materiaL.

- MARVIN PIPKIN.

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