US2305346A - Mirror - Google Patents

Description

Patented Dec. 15, 1942 DIIBBoOB Jolin J.

Hopleiti. Toledo, Ohio, Idlit' Liltlley-Owens-l'ord Glass collllially oledo, Ohio, a corporation of Ohio Application June 19, 1939, I' letilll No. 370,198 4 Claims. (cl. 111-351 This invention relates to mirrors in general and more particularly to the manufacture of glass mirrOrs having metallic reilectlng coatings.

One known method of making mirrors of this type is to apply molten aiuminum to one surface of a glass sheet or plate by spraying the same thereon with a metallizing gun. The present invention contemplates the provision of a novel method of producing mirrors of this type whereby the quality of the mirror and the specular redection of the sprayeci aluminum or other metallic coating is greativ improved. Brieily, this is accomplished by subjecting the metallic coatlng. after it has been applied to the glass, to a relatively high pressure. This can be done in a number of different ways as will be more clearly hereinafter set forth.

I have discovered that by subjecting the metallic coating to a pressure suflicient to induce a ilowing of the metal, a much more brilliant coat of metal is provided in contact with the glass surface. This results in a much sharper specular refiection. I have further found that the use of pressure in this manner results in a mirror exeeedingly stable to weathering and. that the metallic coatina requires no additional treatment for the protection thereof, such as does the common mirror baciring'lldirrors treated in this manner, using aluminun'r cr other metal, are. useful for many rarrpose such as in the home, the rear view mirrors offautomobiles, and. decorative and outdoor mirror,s` of all kinds.

In the cirawing wherein lilre nurnerals are employed to desigrt'ate lille parts throughout the same:

Pig. l is a perspective diagrammatic view showing the spraying of the metal coat upon one surface of a glass sheet; and

Pigs. 2, 3, and 4: are diagrammatic views illustrating three different ways in which the pressure may be applied to the metal coat.

With reference to the drawing. there is illustrated in Pig. 1 the Coating of the upper surface of a glass sheet II as it is supported horizontally upon the top of a suitable table or the like II. The numeral li designates a metallizing gun of any conventional or preferred construction by means of which molten aluminum II is sprayed upon the glass sheet to form a coating li of the desired thiclrness thereon. Although I have referreclto the coating ll as being of aluminum, it will be understood. that the better weathering aiuminum alloys can also be used and the word "aiuminum" as used herein and in the claims is therefore to be understood as also including 55 the suitable aiuminum alloys. Liltewise. other ductile metals. such as, for example, copper, may be used.

After the metallic coating ll has been spra yed upon the glass sheet, it is adapted to be subiecteci to a pressure suilicient to cause a dowing of the metal. This may be done while the metal is still hot or after it is cold. Further, the metal coat may be reheated before the pressure is applied if desired. lis shown in Fig. 2, the pressure is applied by laying the metal coated glass sheet II upon a suitable support IS and passing it beneath a rotatable roll Il. Of course, the support IS may be maintained stationary and the roll li moved thereover if preferred.`

In I"lg. 3, the pressure is applied by passing the metal coated glass sheet IO between a plurality of pairs of pressing rolls i'I and II, while. in Pig. i, the metal coated glass sheet is subiected to pressure between the platens II and 20 of a mechanical or hydraulic platen press.

The pressure may be applied under ordinary room conditions, in prepared atmospheres or in a vacuum. Likewise, any temperature up to the meltlng point of the metal may be used. While the invention is not limited to any particular degree of pressure, the amount of pressure applied should be sufficient to eifect the desired flowing of the metal. Tha words "flow" and "flowing" are used herein to designate a spreading of the metal upon the application of pressure thereto rather than the flowing of metal in a molten condition.

The flowing action of the metal may also be accomplished in other ways. such as by scraping, buffing or burnishing with a suitable tool, wheel, or brush; by machlning or spinning action; hammering or bombardment with shot. It may also be desirable with any of the above pressingoperations to employ Sheets of paper, cloth, leather, resin. or metal or other materials to assist in the flowing of the metal and/or to protect the glass from breairage. Further, lubricants or other materials can be applied to the metal surface to help the process of flow.

I claim:

1. The method of making a glass mirror having a, metallic reflecting coatina, which comprises spraying a coating of molten ductile metal upon the back surface of a transparent glass sheet or plate, and then subjecting said metallic coating topressure sufficient to cause a flowing of the metal at the glass-metal interface to increase specular reflection of the inner surface of the metal in contact With the glass when viewed through the glass sheet or plate.

2. The method of making 9. glass mirror having a metallic reilecting Coating'. which comprises spraying `a coating of moiten altimnum upon the back surface of a transparent glass sheet OI' plate, anti then increasing the specular reiiection of the inner surface of the aiuminum coating in contact With the glass when viewed through the glass sheet or plate by subjecting said altiminum Coating to pressure sufficient to cause 8. Ilowing of the metal at the glass-metal interface.

3. A method of improving the specular reilection of 8. mirror comprising B. transparent glass sheet or plate having a sprayeci coating Of ductile metal upon the back surface thereof, including the step of subjecting the metallic Coating to pressure suiiicient to cause 8, ilowing of the metal at the glass-metal interface.

4. A method OI improving the specular reflection 01' 8 mirror comprising a transparent glass sheet or plate having a sprayeci Coating of aluminum upon the back surface thereof, including the step of subjecting the aiuminum coating to pressure sulflicient to cause the said aiuminum to flow at the glass-metal interface.

JOHN J. I-IOFFIELI).

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