developed by Metronome Records GmbH, a subsidiary of Elektra Records. These new picture discs were made by creating a five-layer lamination consisting of a core of black vinyl with kiln-dried paper decals on either side and then outer skins of clear vinyl film, manufactured by 3M, on the outsides. In manufacture, one layer of the clear film was first placed on the bed of the press on top of the stamper, then a "puck" of hot black vinyl from the extruder was placed on top of that. Finally the top print and vinyl film layer was added (held by a retracting pin in the upper profile usually employed to retain the upper paper label) and the press closed. Problems with poor vinyl flow caused by the paper texture and air released from the paper (that had not been removed in the kiln drying process) plagued the process. The first 'modern' rock picture disc was introduced as an assortment of artists such as the MC5 and The Doors. It was released in 1969 by Metronome of Germany and entitled "Psychedelic Underground - Off 2, Hallucinations". The second release was the British progressive rock band Curved Air's first album, Air Conditioning, a UK issue (1970). One commercially issued American picture disc is To Elvis: Love Still Burning, a collection of 11 Elvis Presley tribute songs by various artists, issued in May 1978. Both sides of the album (Fotoplay FSP-1001) picture Presley. Initially picture discs were usually promotional items pressed in small quantities, but by the late 1970s they began to be produced as commercial products in large quantities. In the 1980s numerous commercial picture discs were released, but by the end of the decade, the interest in picture discs had declined as consumers began transitioning away from vinyl records towards newer formats such as cassette tapes and compact discs. Types of picture discs On some picture discs, the images used were meant to create an optical illusion while the record was rotating on the turntable (as in the B side of Curved Air's Airconditioning), while others used the visual effect to add to the music — for example, the 1979 picture disc of Fischer-Z's The Worker featured a train which endlessly commuted around the turntable, reinforcing the song's message. Later picture discs included liquid light show style fluids between the vinyl, Rowlux 3D effect film, diffraction rainbow film, metal flake (vide examples