https://en.wikipedia.org/wiki/Marvin_Pipkin?mc_cid=f3e05c714c&mc_eid=544159cdb1#Light_bulb_innovations Clear transparent incandescent lamps give off a sharp light, which is unpleasant to many people, and also makes it hard to see objects close to the lamp. In 1920, General Electric developed a 30 watt light bulb that had outside etching as a frosting effect. It effectively diffused the light to make it softer; however, it decreased the light produced by 15–25 percent. Another problem with the lamp was that fluorides used in the etching attacked the tungsten filament, and that external etching of the globe bulb weakened it. The rough outside surface collected dust and dirt and was difficult to clean. The etched bulbs were brittle and would often break with ordinary handling. When Pipkin went to work for General Electric he was assigned the supposedly impossible task of finding a way to frost electric light bulbs on the inside without weakening the glass. He was not aware that this assignment was considered a fool's errand, so he went about the task as if it were something that could be done. Pipkin produced an innovative acid etching process for the inside of the globe of an electric lamp so that it did not deteriorate the lamp glass globe. His was a two step acid process that etched the interior of glass with tiny crevasses on the first process like in the normal procedure, but he added a second acid step that caused soft, rounded dimples from the crevasses which gave the bulbs added strength. There was minimal loss of diffusion of light with his innovation. It left the outside of the globe of the glass lamp smooth so that it did not hold dust like those etched on the outside. The first electric light bulb frosted on the inside with sufficient strength for ordinary handling that could be sold to the public was invented by Pipkin in 1925. Patent No. 1,687,510 was issued to Pipkin on October 16, 1928, and by him assigned to his employer, General Electric Co. On November 5, 1945, however, the United States Supreme Court invalidated the patent, on the ground that the claimed invention was not sufficiently original. This idea of having a second treatment to smooth out the fine-grained texture to dimples came about by accident. Pipkin would often clean out the experimental bulbs with another solution of the acid, but in a weaker solution. If he left the filled bulb for a while with this weaker solution it would clean out the etching previously done and return the glass globe to its transparent state. This made it possible to repeat an etching experiment on the following day. One day, while he was pouring the weaker solution into a bulb, the phone rang. In the process of answering the phone, he accidentally tipped the bulb over before it had enough time to finish cleaning out the previous etching. When he returned to his work, he accidentally knocked the glass bulb off the workbench and onto the floor. To his surprise it did not shatter, as etched bulbs normally did, but bounced a few times and then rolled under the workbench. Pipkin was surprised to find that the bulb glass had somehow become much stronger. As it turned out, a short bath in the weaker cleaning solution, not long enough to remove the etching, caused the etching of the first frosting treatment to form dimples in the etching, that strengthened the glass. Pipkin did a demonstration of the bulbs' integrity to his supervisor at General Electric. He presented to his supervisor six light bulbs that had been frosted on the inside. Some had just the one application of acid and others with his reinforced second treatment. He placed the bulbs on his supervisor's desk, standing up on their screw bottoms. He tipped the first three over, one at a time, to simulate a bulb being dropped from a small height. These were the bulbs treated with original single acid application, and as expected, all three bulbs shattered. He then tipped over the remaining three bulbs, which were tempered with his new two-step acid treatment. They remained unbroken, much to the surprise of his supervisor. Then, to further demonstrate the effectiveness of his tempering process, Pipkin took bulbs that had not shattered and dropped them again, this time allowing them to fall to the office floor. The bulbs bounced on the floor, and settled without breaking. Pipkin's new frosted bulb revolutionized the industry, allowing the manufacture of frosted bulbs that diffused the light without losing much intensity, and were strong enough to be commercially viable. He went on to make many innovations to the light bulb and two decades later developed the soft white light bulb.