Tape Degradation Factors and Predicting Tape Life Richard L. Hess Aurora, Ontario, Canada Richard L. Hess ARSC Milwaukee Dietrich Schuller says: The world's stock of audio recordings is estimated to be more than 50 Mh (million hours) of materials. None of these recordings are on permanent carriers Richard L. Hess ARSC Milwaukee Kings College London says: Seventy percent of all audiovisual material is under immediate threat of deterioration, damage or obsolescence and seventy percent of collection managers don't know it. Richard L. Hess ARSC Milwaukee The Challenge Archives hold tapes from the 1940s on Archives hold tapes from the 1940s on The tapes are degrading The tapes are degrading Few new playback machines are made Few new playback machines are made Multiple factors involved in the degradation Multiple factors involved in the degradation Only limited research has been done Only limited research has been done Recommendations for tape differ from film Recommendations for tape differ from film Some tapes may degrade before its their turn to be copied Some tapes may degrade before its their turn to be copied Richard L. Hess ARSC Milwaukee Conceptual Timeline Richard L. Hess ARSC Milwaukee Components Base film Base film Binder/oxide Binder/oxide Lubricant Back coating (later tapes) Back coating (later tapes) All contribute in varying degrees to tape degradation All contribute in varying degrees to tape degradation Richard L. Hess ARSC Milwaukee Base film degradation modes Acetate Acetate Vinegar Syndrome Brittleness/Drying out, Shrinkage Polyester (PET) Polyester (PET) Warping, especially with tensilized PET PVC and Paper PVC and Paper Slow weakening due to aging Richard L. Hess ARSC Milwaukee General degradation modes Tape pack defects Tape pack defects Spoking Folded wraps Popped strands Reel defects Reel defects Weak hubs Warped flanges Richard L. Hess ARSC Milwaukee Acetate base film 1935 1972 Vinegar syndrome slowed by freezing Vinegar syndrome slowed by freezing Freezing is considered bad for tape Freezing is considered bad for tape Vinegar syndrome is left to advance, but it is doing so slower than film Vinegar syndrome is left to advance, but it is doing so slower than film Will it plateau or continue? Canadian Conservation Institute has plans to research freezing tape Canadian Conservation Institute has plans to research freezing tape Richard L. Hess ARSC Milwaukee Acetate degradation Reel window imprint Corrosion 1943 German Acetate tape showing cracking and corrosion caused by the acetic acid of vinegar syndrome and related shrinkage From the Ampex Museum collection at Stanford, photo by author Richard L. Hess ARSC Milwaukee PVC & Paper base film Degradation is not as fast as acetate Degradation is not as fast as acetate Paper in general is known to respond well to freezing Paper in general is known to respond well to freezing So far, PVC tape has been stable So far, PVC tape has been stable There is worry about the plasticizers in PVC tape PVC was made 19431972 PVC was made 19431972 Paper was made 1940s1950s Paper was made 1940s1950s Richard L. Hess ARSC Milwaukee PET: Polyethylene terephthalate Also known as Mylar (DuPont TM) Also known as Mylar (DuPont TM) Generically called a Polyester Generically called a Polyester PET is probably the most stable and least problematic of historic base films PET is probably the most stable and least problematic of historic base films Tensilized PET is potentially more problematic (aka Tenzar, 3M TM) Tensilized PET is potentially more problematic (aka Tenzar, 3M TM) It is hygroscopic and can move water to the back of the coatings It is hygroscopic and can move water to the back of the coatings Richard L. Hess ARSC Milwaukee Binder failures Soft Binder Syndrome (SBS) Sticky Shed Syndrome (SSS) Pinning / Blocking Binder-base adhesion failure Richard L. Hess ARSC Milwaukee Soft Binder Syndrome (SBS) Tape squeals, may leave some debris Tape squeals, may leave some debris Baking may or may not solve problem Baking may or may not solve problem If baking works, then it is Sticky Shed Syndrome Sticky Shed is a subset of SBS Richard L. Hess ARSC Milwaukee Soft Binder Syndrome Causes All SBS seems to be caused by binder hydrolytic breakdown All SBS seems to be caused by binder hydrolytic breakdown Polyester-Polyurethane binders suffer most Polyester-Polyurethane binders suffer most Glass transition temperature T g is lowered Glass transition temperature T g is lowered T g is the temperature above which the substance becomes rubbery T g is the temperature above which the substance becomes rubbery It can be below room temperature Richard L. Hess ARSC Milwaukee Soft Binder Syndrome T g 3M 175 Currently T g +8C (46F) 3M 175 Currently T g +8C (46F) One reel of 175 did not immediately respond at about 38F (3F), but did after two days of cold soak One reel of 175 did not immediately respond at about 38F (3F), but did after two days of cold soak Removing moisture may raise the T g somewhat Removing moisture may raise the T g somewhat The reactions are not truly reversible in a filled matrix The reactions are not truly reversible in a filled matrix Richard L. Hess ARSC Milwaukee Soft Binder Syndrome Solution Since the T g has become lower Since the T g has become lower Its difficult to raise the T g Its difficult to raise the T g We wish to play the tapes We wish to play the tapes What can we do? What can we do? One solution suggests itself One solution suggests itself Richard L. Hess ARSC Milwaukee Soft Binder Syndrome Solution Richard L. Hess ARSC Milwaukee Soft Binder Syndrome Solution This worked with 3M/Scotch 175 This worked with 3M/Scotch 175 This worked with Sony PR-150 This worked with Sony PR-150 Both of the above tapes were Both of the above tapes were Previously unplayable Did not respond to baking Partially responsive to relubrication Richard L. Hess ARSC Milwaukee Soft Binder Syndrome Solution ALL heads and guides were in place for this test ALL heads and guides were in place for this test We used the high tension (large reel) setting to make this a tougher test We used the high tension (large reel) setting to make this a tougher test Environment approx +4 C; 25% RH Environment approx +4 C; 25% RH This has worked in other tests as well This has worked in other tests as well Richard L. Hess ARSC Milwaukee Soft Binder Syndrome Alternate 3M/Scotch 175 did respond to 3M/Scotch 175 did respond to Cleaning, Removing all stationary guides/heads except play head, and Reduced tension Sony PR-150 did not respond to this at room temperature Sony PR-150 did not respond to this at room temperature Richard L. Hess ARSC Milwaukee Sticky shed syndrome (SSS) Back-coated mastering tapes Back-coated mastering tapes The two coatings appear to interact Leaves hard-to-remove debris Leaves hard-to-remove debris The layers sometimes adhere to each other (blocking / pinning) The layers sometimes adhere to each other (blocking / pinning) Therefore, use caution when evaluating the previous technique with these tapes Richard L. Hess ARSC Milwaukee Sticky shed syndrome (SSS) Responds to baking Responds to baking Tapes NOT as good as new Multiple baking may degrade tape Last Ditch Effort to recover content May be getting worse with time Baking does not re-link the chains but temporarily raises the T g and appears to reduce the pinning. Baking does not re-link the chains but temporarily raises the T g and appears to reduce the pinning. Richard L. Hess ARSC Milwaukee Sticky shed syndrome (SSS) Ric Bradshaw, IBM/Challenger tape hypothesizes, Ric Bradshaw, IBM/Challenger tape hypothesizes, All of the back coatings are far more binder rich than the magnetic coatings and their modulus is half that of the magnetic coatings due to the very poor reinforcement of carbon black. I believe what happens is that the back coating and magnetic coating are compressed into a high pressure contact during storage, and since the binders in both are essentially the same, they intermix and entangle over time such that when you pull them apart some of the magnetic coating and some of the back coating are transferred to each other as they separatepull-outs. This deposit is above the normal surface and is clipped off onto the head during tape motion. The frictional heating is enough to make the debris melt to the head and it can be very difficult to clean off. Richard L. Hess ARSC Milwaukee Pinning / Blocking Binder adheres to next layers back Binder adheres to next layers back Binder/oxide is ripped out Binder/oxide is ripped out Increases with higher tension, usually near hub Increases with higher tension, usually near hub Anecdotal evidence supports: Anecdotal evidence supports: Cold soak* Slow unwinding Rehumidification May happen with SSS tapes May happen with SSS tapes *A month at +4C with silica gel packet Richard L. Hess ARSC Milwaukee Binder-base adhesion failure Binder/oxide delaminates from base film Binder/oxide delaminates from base film Not widespread Not widespread May affect Ferro- Chrome (Type III) cassettes more than other tapes May affect Ferro- Chrome (Type III) cassettes more than other tapes May respond to cold soaking May respond to cold soaking Richard L. Hess ARSC Milwaukee Factors influencing degradation Tape formulation / component selection Component degradation / failure Manufacturing defects / tolerances Storage conditions Playback without proper conditioning Playback on defective equipment Richard L. Hess ARSC Milwaukee Prioritization of preservation Assessment tools such as FACET by Mike Casey at Indiana University Assessment tools such as FACET by Mike Casey at Indiana University Identifying at-risk tape types/batches Identifying at-risk tape types/batches Running changes make this difficult Tapes can have multiple formulations during their run Rank importance as well as risk Rank importance as well as risk Richard L. Hess ARSC Milwaukee Anticipated lifetimes Manufacturer design life: 1020 years Manufacturer design life: 1020 years Oldest tapes are approaching 60 years Oldest tapes are approaching 60 years Some 30-year-old tapes difficult to play Some 30-year-old tapes difficult to play Player obsolescence is now Player obsolescence is now Studer is supporting the A807 thru 2010 Studer is supporting the A807 thru 2010 Only available reel player: Otari 5050 Only available reel player: Otari 5050 No new top-of-the-line cassette players No new top-of-the-line cassette players Richard L. Hess ARSC Milwaukee Prediction of life Low reliability of tape life prediction Low reliability of tape life prediction Life can be batch-specific Life can be batch-specific Cannot rely on tape box to ID tape Cannot rely on tape box to ID tape Most tapes are now past design life Most tapes are now past design life Past storage history Past storage history May adversely affect life Usually unknown and unknowable Richard L. Hess ARSC Milwaukee Prediction of life: Measurement Bradshaw is thinking that T g might be the degradation indicator we wish for Bradshaw is thinking that T g might be the degradation indicator we wish for It is not trivial to measure the mechanical properties of the mag coating off the base film! It is not trivial to measure the mechanical properties of the mag coating off the base film! A pool test kit is considered unlikely A pool test kit is considered unlikely Richard L. Hess ARSC Milwaukee Ongoing research Prestospace in Europe Prestospace in Europe Working to define the preservation factory Looking for markers to prioritize assets Canadian Conservation Institute Canadian Conservation Institute Has evaluated optical media Is planning on revisiting freezing of tape Library of Congress Library of Congress Major upcoming initiatives Richard L. Hess ARSC Milwaukee What to do ? Optimize storage conditions Optimize storage conditions Prioritize copying Prioritize copying Copy (aka reformat) Copy (aka reformat) Store multiple copies Store multiple copies Use geographically diverse repositories Use two different, unrelated media Develop a media evaluation and refresh plan for copies and stick to it Develop a media evaluation and refresh plan for copies and stick to it Richard L. Hess ARSC Milwaukee When ? Now Now If you wish to preserve it, you must start the program now If you wish to preserve it, you must start the program now Not all tapes are failing, but do you know which ones are? Not all tapes are failing, but do you know which ones are? Dont delay starting in earnest Dont delay starting in earnest Do it now now now now Do it now now now now Richard L. Hess ARSC Milwaukee When ? Now Richard L. Hess ARSC Milwaukee What is in typical archives? GOODFilesCDsBADReelsRecordsUGLYDATsCassettesPCM-F1Minidisc Richard L. Hess ARSC Milwaukee The ugly DAT is dead DAT is dead PCM F-1 is petrified PCM F-1 is petrified Cassettes are a carcass Cassettes are a carcass MD is moribund MD is moribund Dont assume any of these formats will be playable in years Dont assume any of these formats will be playable in years Transfer NOW! Transfer NOW! Richard L. Hess ARSC Milwaukee The bad Records are what they are Records are what they are Still playable Most manufactured records are not decaying Many original lacquers are at great risk Tapes are decaying Tapes are decaying Machine obsolescence Operator obsolescence Tape degradation Richard L. Hess ARSC Milwaukee The good CDs should be playable for 50+ years CDs should be playable for 50+ years Disk lifetime probably greater for gold phthalocyanine dye CDs (MAM-A) Fragile Easily cloned Supports shelf storage model Limited to 16 bit 44.1 ks/s Richard L. Hess ARSC Milwaukee The better IT Infrastructure IT Infrastructure Move from shelf storage to file storage Audio files are just another file that needs to be stored, backed up, migrated, and returned to the user Automatic backups Little manual intervention Management required Richard L. Hess ARSC Milwaukee Topology Varied technologies Varied technologies Spinning Disk LTO-3 tape Metadata Metadata Rich index of what is in archive Richard L. Hess ARSC Milwaukee Security Multiple disk copies Multiple disk copies Multiple tape copies Multiple tape copies Off-site storage Off-site storage Dont forget storage on different plates, away from faults Dont forget storage on different plates, away from faults Richard L. Hess ARSC Milwaukee What archive format? Broadcast Wave Broadcast Wave Almost everything can use WAV files It will survive EBU has found it useful Eliminates confusion 1 TB holds about 1,000 channel hours of 96/24 PCM WAV files Richard L. Hess ARSC Milwaukee What about other formats? Dont try and mix formats, but multiple bit/sample rates may be acceptable Dont try and mix formats, but multiple bit/sample rates may be acceptable Down convert for delivery Down convert for delivery Convert to the archive format if other formats are ingested, dont rely on long-term codec availability Convert to the archive format if other formats are ingested, dont rely on long-term codec availability Richard L. Hess ARSC Milwaukee Storage overview Archival storage must be Archival storage must be Understood Funded Designed Organized Populated Managed in perpetuity Richard L. Hess ARSC Milwaukee Storage management Dont risk losing audio material Dont risk losing audio material Dont trust dedicated formats long term Dont trust dedicated formats long term Nothing is certain but change Nothing is certain but change IT data loss rarely happens IT data loss rarely happens IT migrates for long term storage IT migrates for long term storage Data management is well understood Data management is well understood Richard L. Hess ARSC Milwaukee Summary If the content matters to you, do not rely on old tape. If the content matters to you, do not rely on old tape. New data tape is fine, as long as there is a plan to refresh it over time. New data tape is fine, as long as there is a plan to refresh it over time. Just because you cant play the tape doesnt mean its not recoverable. Just because you cant play the tape doesnt mean its not recoverable. Tapes are not getting better with age. Tapes are not getting better with age.