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By 2007, 200 billion CDs (including audio CDs, CD-ROMs and CD-Rs) had been sold worldwide. Standard CDs have a diameter of 120 mm (4.7 in), and are designed to hold up to 74 minutes of uncompressed stereo digital audio or about 650 MiB ( 681,574,400 bytes) of data.
The metal coats the data side of the disc (upper surface), covering the pit and lands. This metal layer is the reflective surface which can be seen on the reverse (non-label side) of a CD. This thin layer of metal is subject to corrosion from various contaminants and so is protected by a thin layer of lacquer. CDs are printed in waterless offset
The CD jewel case is designed to carry a booklet, as well as to have panel inserts. These may be used to display album artwork, lyrics, photos, thank-yous, messages, biography, etc. [5] Because the CD jewel case is the standard, most commonly used CD case, it is much cheaper. The price of the CD jewel case usually ranges from $0.75 to $0.95.
An optical disc is designed to support one of three recording types: read-only (such as CD and CD-ROM), recordable (write-once, like CD-R), or re-recordable (rewritable, like CD-RW). Write-once optical discs commonly have an organic dye (may also be a ( phthalocyanine ) azo dye , mainly used by Verbatim , or an oxonol dye, used by Fujifilm [ 4 ...
Disc rot is the tendency of CD, DVD, or other optical discs to become unreadable because of chemical deterioration. The causes include oxidation of the reflective layer, reactions with contaminants, ultra-violet light damage, and de-bonding of the adhesive used to adhere the layers of the disc together.
The preservation of optical media is essential because it is a resource in libraries, and stores audio, video, and computer data. While optical discs are generally more reliable and durable than older media types, (magnetic tape, LPs and other records) environmental conditions and/or poor handling can result in lost information.
Candle toppers are cute, open metal lids that often have intricate designs. Like the aluminum foil, they help keep the flames protected from wind and drafts so the wax can melt evenly.
Bombs on London recorded on an aluminum disc by the British Broadcasting Corporation in 1940 on display at the CBC Museum. In the field of audio recording, an aluminum disc (aluminium in the UK and elsewhere) is a phonograph (gramophone in the UK) record made of bare aluminum, a medium introduced in the late 1920s for making one-off recordings.