When auto-changing turntables were commonplace, records were typically pressed with a raised (or ridged) outer edge and label area. This would allow records to be stacked onto each other, gripping each other without the delicate grooves coming into contact, thus reducing the risk of damage. Auto changing turntables included a mechanism to support a stack of several records above the turntable itself, dropping them one at a time onto the active turntable to be played in order. Many longer sound recordings, such as complete operas, were interleaved across several 10-inch or 12-inch discs for use with auto-changing mechanisms, so that the first disk of a three-disk recording would carry sides 1 and 6 of the program, while the second disk would carry sides 2 and 5, and the third, sides 3 and 4, allowing sides 1, 2, and 3 to be played automatically, then the whole stack reversed to play sides 4, 5, and 6.
The sound quality and durability of vinyl music records is highly dependent on the quality of the vinyl. During the early 1970s, as a cost-cutting move towards use of lightweight, flexible vinyl pressings, much of the industry adopted a technique of reducing the thickness and quality of vinyl used in mass-market manufacturing, marketed by RCA Victor as the "Dynaflex" (125 g/m²) process, considered inferior by most record collectors. Most vinyl records are pressed on recycled vinyl.
New "virgin" or "heavy" (180-220 g/m²) vinyl is commonly used for modern "audiophile" vinyl releases in all genres. Many collectors prefer to have 180 g/m² vinyl albums, and they have been reported to have a better sound than normal vinyl. These albums tend to withstand the deformation caused by normal play better than regular vinyl180 g/m² vinyl is more expensive to produce and requires higher-quality manufacturing processes than regular vinyl.
Since most vinyl records are from recycled plastic, impurities can be accumulated in the record, causing a brand new album to have audio artifacts like clicks and pops. Virgin vinyl means that the album is not from recycled plastic, and will theoretically be devoid of the possible impurities of recycled plastic. In practice, this depends on the manufacturer's quality control.
The orange peel effect on vinyl records is caused by worn moulds. Rather than having the proper mirror-like finish, the surface of the record will have what looks like an orange peel texture. This introduces noise into the record, particularly in the lower frequency range. It should be noted that with direct metal mastering (DMM) the master disc is cut on a copper-coated disc which can also have a minor "orange peel" effect. As this "orange peel" originates in the master rather than being introduced in the pressing stage, there is no ill-effect.