The White MAZDA Lamp
The bulbs of incandescent lamps made prior to about 1920 were generally manufactured clear, but outside frosting by etching or sandblasting was available on some lamps. By their nature clear bulbs gave glare, which resulted in discomfort for many persons. The outside frosting had at least two drawbacks. It resulted in a weakening of the glass and the outside rough surface was difficult to wipe clean. In terms of light loss by absorption, it decreased it by about 10%².

A bulb was developed about 1920 that diffused the light so that the glare problem was nearly eliminated. This lamp, known as the White MAZDA, had a bulb made of a special white glass¹. A performance drawback of the special glass was that it absorbed more light than did the frosted bulb. It reduced the light level by 15%². The glass was used for the straight wire vacuum MAZDA lamp with the exhaust tip but then a tipless lamp was introduced which was gas-filled and employed a coiled tungsten filament. The exhaust method was that developed by L. E. Mitchell and A. J. White at Nela Park in 1919. A picture of both lamps follows. The new tipless pear shaped lamp shown is a 50-watt, 115-volt design, with a maximum overall length of 5-1/8 inches. The maximum diameter of the tipless lamp is 2-1/2 inches whereas the lamp with the tip has a maximum diameter of 2-3/8 inches.

The inside frost technique developed by Marvin Pipkin about 1924 did not diffuse the light as well as the white glass lamp but the light loss was only about 1-1/2% instead of the 15% in the White MAZDA³.

References
1) "The White Mazda Lamp", Earl A. Anderson, General Electric Review, Vol XXIII, No 8, Aug 1920, pg 712.
2) Paul W. Keating, Lamps for a Brighter America - A History of the General Electric Lamp Business, McGraw-Hill Book Co., Inc., 1954, pg 126.
3) C. E. Weitz, General Electric Lamps - A Condensed Text on the Design and Operation of Incandescent, Mercury and Fluorescent Light Sources, Large Lamp Department, General Electric Co., Cleveland, OH, Jan 1956, pg 24.

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