By the 1940s, 10” 78rpm discs were still the norm. By the end of the war, a new material called polyvinyl chloride (PVC), commonly known solely as “vinyl” had started to come into use, which in comparison to fragile shellac was relatively unbreakable and with a smaller grain structure. This made it capable of more refined impressions. They would be known as “microgroove discs” and allowed for broader frequencies and dynamics. As well, a new standard speed for record playback emerged that allowed for longer playing times – a major benefit for jazz artists. The 331/3rpm “long-playing” (LP) record was first introduced by Columbia in 1948, and with a diameter of 12”, 25 minutes of music could fit on one side of the disc.
Interestingly, this was not the first disc of its kind. Electrical transcriptions for radio used the 33rpm speed and vinyl material in the 1930s. Various experiments with playback speeds and disc materials took place almost at the advent of commercial discs themselves. Therefore, the switch from 33 to 78 and shellac to vinyl didn’t occur over night. When Columbia unveiled their 12” vinyl, they also introduced 10” vinyl, perhaps in keeping with the public’s familiarity with 78 rpm singles. These albums held up to 15 minutes per side and approximately 3 songs, but by the mid-1950s, these largely fell out of fashion amongst popular music listeners who wished to hear more music on one side.