Fewer than half of American adults floss their teeth daily, according to Colgate-Palmolive. So the toothpaste maker teamed up with Eastman Chemical Co., Kingsport, Tenn., to develop a toothbrush that provides 75% of the benefit of flossing by removing plaque between teeth and along the gum line. Eastman’s Eastar copolyester was chosen as the base component after passing chemical resistance, breakage, and appearance tests. The material is said to mold well and bonds with the elastomer chosen for the brushes. It costs less than other toothbrush materials with the advantage of being chemically resistant to peppermint and spearmint oils found in toothpastes. It doesn’t break at weld lines, has high bristle retention, and resists creep.
30 YEARS AGO NOVEMBER 9, 1978 2:1 safety factor built into large worm gear: A 54-in. center wormgear set was machined by the Cleveland Div., Eaton Corp. The 4,300-lb bronze gear ring has a diameter of 8… ft. The mating worm weighs 2,000 lb. The gear will drive a shaft that will rotate the bowl of a coal pulverizer. Rated at 1,150 hp, the gear will be coupled to a 600-hp motor. The safety factor was designed into the gear to avoid problems when foreign objects such as railroad spikes become mixed in with the coal, causing sudden increases in load when debris enters the pulverizer.
50 YEARS AGO NOVEMBER 13, 1958 Porsched computer wins sportscar rally: By figuring distances to within 0.001 mile, two missile engineers and a calculator riding in a Porsche easily won a precision driving contest in New Mexico. The contest required exact maintenance of a predetermined speed over a severalhundred- mile route. The engineers, from Telecomputing Corp., took turns driving and feeding data from a tachometer and chronometer into the calculator to determine speed corrections every 3 min. Their calculations included an allowance for tire expansion due to heat.