at the time the lp was introduced, nearly all phonograph records for home use were made of an abrasive (and therefore noisy) shellac compound, employed a much larger groove, and played at approximately 78 revolutions per minute (rpm), limiting the playing time of a 12-inch diameter record to less than five minutes per side. the new product was a 12- or 10-inch (30 or 25 cm) fine-grooved disc made of pvc ("vinyl") and played with a smaller-tipped "microgroove" stylus at a speed of  rpm. each side of a 12-inch lp could play for about 22 minutes. only the microgroove standard was new, as both vinyl and the  rpm speed had been used for special purposes for many years, as well as in one unsuccessful earlier attempt (by rca victor) to introduce a long-playing record for home use.