what causes audio tape to screech and squek
Reel of magnetic audiotape
Sticky-shed syndrome is a status created past the deterioration of the binders in a magnetic tape, which agree the ferric oxide magnetizable coating to its plastic carrier, or which hold the thinner back-coating on the exterior of the record.[i] This deterioration renders the tape unusable.[2] Some kinds of binder are known to pause downward over fourth dimension, due to the absorption of moisture (hydrolysis).
The symptoms of this breakdown tin be immediately obvious even when rewinding the record: tearing sounds and sluggish behavior.[iii] If a tape with sticky-shed syndrome is played, the reels will brand screeching or squeaking sounds, and the tape volition go out dusty, rusty particles on the guides and heads.[4] In some cases, particularly with digital tapes, the symptoms are more subtle, causing intermittent dropouts.
Cause [edit]
Some tapes may deteriorate considering of a breakdown in the binder (the glue) that holds the oxide particles on the tape, or the back coating on the opposite side, if the tape was from whatever of the tape manufacturers who had inadvertently used an unstable folder formulation. That binder contained polyurethane that soaks up water (Hydrolysis) and causes the urethane to rise to the record's surface.[ commendation needed ] This problem became known as the 'sticky-shed syndrome'. One explanation offered was that short strands of urethane were usually used in tapes until it was discovered that mid-sized strands are improve and were good at absorbing moisture.[3] Baking the tape at depression temperature may temporarily restore the tape by driving the water molecules from the folder so that it tin can be safely copied to another record or a different format. Afterward baking, the tape may remain in skilful status for approximately a month. If the tape re-deteriorates, it may exist possible to bake the record again.
Afflicted stock [edit]
Many tapes affected by sticky-shed are those that were fabricated by Ampex/Quantegy such as 406/407, 456/457, 499, and consumer/audiophile course dorsum coated tapes such every bit Grand Master and 20-twenty+.
Tapes made past Scotch/3M are also affected and the nearly common offenders here are the "pro" tapes such equally 206/207, 226/227, 262 (though not all 262 is backcoated and therefore isn't afflicted), 808, and 986 equally well as audiophile tapes such as "Classic" and "Master-XS".
Though less common, many Sony branded tapes such as PR-150, SLH, ULH, and FeCr have besides been reported to suffer from glutinous-shed.
Blank cassettes from the 70s-90s are unaffected because the hygroscopic binder was not used in cassette formulations. Even so, some cassette tape formulations do endure from a like problem caused by fatty acids working to the surface of the tape that tin crusade sticking to heads and guides and severe modulation of signals through the playback head until it is cleaned.
Ampex-branded u-matic cassette tapes are also now exhibiting viscous-shed issues, similar to their reel tape media.
As of 2012, there are no documented or proven examples of sticky-shed from Maxell. TDK has been showing signs as of belatedly of shedding its lubricant in the form of a white powder or white/yellowish goo. This has shown up on the TDK SA and some LX and BX tapes.[ citation needed ] There accept been a few reports of some tape from the current manufacturers ATR and RMGI exhibiting symptoms of sticky-shed. But these may be isolated incidents relating to paradigm or single bad batches and are not necessarily indicative of the overall product line integrity.
BASF tape product did not use the unstable conception, and their tape production rarely shows this type of coating instability, although BASF LH Super SM cassettes manufactured in the mid-70s are prone to the problem. Certain batches of Chromdioxid Extra II C-90s, produced around 1989-1991 and sold in the Britain, shed a white powder that would coat the record/playback head afterward a few months of use. The slightly higher performance Chromdioxid Super 2 and Chromdioxid Maxima C-90 cassettes were unaffected.
As of 2015, some 35 mm magnetic fullcoat tapes produced past Kodak, such as those used for the audio portion of older IMAX films, are also reported to exist exhibiting sticky-shed.[five] As tapes remain in storage for a longer fourth dimension, information technology is possible that other folder formulations may develop problems.
Solutions [edit]
The binder on this record has deteriorated to the extent that the oxide (brownish), which holds the magnetic data, has come up away from the polyester base (clear). Information technology is unrecoverable.
Current solutions to sticky-shed syndrome seek to safely remove the unwanted wet from the tape binder. Two different strategies are commonly employed: applying rut to the tape (usually chosen 'baking'), and changing the environment to lower the humidity. Baking is widely good only can destroy tapes. While modification of humidity by safely decision-making the environment may take significantly longer, its major do good is that it does non irreparably damage the tape. Culling practices have also been developed by engineers to repair afflicted tapes.
Baking [edit]
Baking is a mutual practice for temporarily repairing sticky-shed syndrome. There is no standard equipment or practice for blistering, then each engineer is left to create their own methods and materials. More often than not, tapes are baked at depression temperatures for relatively long periods of time, such as 130 °F to 140 °F (54 to 60 °C) for 1 to 8 hours.[vi] Wider record formats may accept longer. It is commonly thought that blistering a tape volition temporarily remove the moisture that has accumulated in the binder. A treated tape will reportedly part like new for a few weeks to a few months earlier it will reabsorb moisture and be unplayable once again.[7]
Baking cannot be used with acetate tapes, nor is information technology needed.[3] Baking is likewise much less effective with U-matic tapes equally the cases for those tapes prevent effective air circulation within the tape media, limiting its ability to remove moisture.
Necessity [edit]
Tape baking is a somewhat risky procedure, since in that location is a risk of dissentious the tape from the heat. Nevertheless, there are some important signs that show when a tape needs baking. The usual symptom is squealing when the tape passes the playback head or other fixed parts of a tape player. The squealing is audible direct from the tape and usually as well transmitted electronically through the output of the tape recorder as a wideband distortion of the playback point. Continuous use of a squealing tape risks permanently damaging the tape, equally oxide is sometimes torn off the record. This flaking residue can exist seen and can experience gummy while nevertheless on the tape's surface. There is likewise a risk of damage to the player. Another symptom is the record sounding dull and distorted. In a video recording, degradation can exist represented by acoustic dropouts.[viii]
References [edit]
- ^ Hess, Richard. "Tape Degradation Factors and Challenges in Predicting Tape Life" (PDF). richardhess.com. ARSC Journal XXXIV / ii 2008 Conference paper.
- ^ Pearce-Moses, Richard. "A Glossary of Archival and Records Terminology". Retrieved 2009-08-12 .
- ^ a b c Ciletti, Eddie. "If I Knew You lot Were Coming I'd Have Broiled A Tape!". Retrieved 2009-08-12 .
- ^ Rarey, Rich. "Baking Former Tapes is a Recipe for Success". Archived from the original on 2011-07-16. Retrieved 2009-08-12 .
- ^ "Looking for DTAC soundtrack of THE GREATEST PLACES". Retrieved xv September 2015.
- ^ Ciletti, Eddie. "Sleep Like an Egyptian". Archived from the original on 2008-06-12. Retrieved 2009-08-12 .
- ^ Rivers, Mike. ""Baking" Magnetic Record To Overcome The "Sticky-Shed" Syndrome". Retrieved 2009-08-12 .
- ^ Van Bogart, J. W. C. (June 1995). Magnetic tape storage and handling. Washington, DC: Commission on Preservation and Access.
Further reading [edit]
- Holmes, T. (Ed.) (2006). The Routledge guide to music engineering science. New York: Taylor & Francis Group.
External links [edit]
- Much info on recovering vintage video(tapes)
- Explanation on "sticky-shed" syndrome
- 'Dealing with "glutinous-shed syndrome
- List of some specific analog reel tape types and manufacturers known to require blistering
- Clan of Moving Image Athenaeum on sticky-shed syndrome for Videotape
- Footstep-by-step guide on tape baking by Dave Luepke
- Cups 'N Strings saves l Record Plant live recordings.
- Master preservation
- Record Resources Online
- Super Oldies Reel Tape Baking Guide
- Method confirmed and it works
hardnettthimend1940.blogspot.com
Source: https://en.wikipedia.org/wiki/Sticky-shed_syndrome
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