This lovely piece which disguises the appearances of the bands in a flowerpot is signed for you by Victor Moscoso. The headliners, Blue Cheer played in a psychedelic blues rock style, and are also credited as being some of the earliest pioneers of heavy metal, with their cover of "Summertime Blues" sometimes cited as the first in the genre. They have also been noted as influential in the development of genres as disparate as punk rock, stoner rock, doom metal, and grunge. Eric Clapton defined them as "probably the originators of heavy metal".
"Blue Cheer" was the name of a variety of LSD made by chemist and Grateful Dead patron Owsley Stanley and the band was probably named for that, although the name existed earlier, as the name of a laundry detergent for which the LSD variety itself was named. The band was managed by an inactive member of the Hells Angels named Allen "Gut" Terk, who also designed a few posters for Hell’s Angels parties featuring SF-based bands.
Their first hit (OK, their only hit) was the cover version of Eddie Cochran's "Summertime Blues" from their debut album Vincebus Eruptum (1968). The single peaked at No. 14 on the Billboard Hot 100 chart, and the album peaked at No. 11.
Victor Moscoso was born in Spain but raised in Brooklyn, studying art at Cooper Union and later Yale under Joseph Albers. Moscoso's use of vibrating colors was influenced by painter Josef Albers, one of his teachers at Yale. He moved to San Francisco in 1959, attending and later teaching at the San Francisco Art Institute. In 1966 he noticed the psychedelic posters being created by Wes Wilson and Mouse and Kelley and immediate wanted to be part that scene. He created a handful of posters in the Fall of 1966 but by December had become a leading producer and one of the “Big Five” San Francisco psychedelic poster artists.