1. Tape Degradation Factors and Predicting Tape Life Richard L. Hess Aurora, Ontario, Canada

2. Richard L. Hess ARSC Milwaukee 2007-05-042 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…”

3. Richard L. Hess ARSC Milwaukee 2007-05-043 King’s 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.

4. Richard L. Hess ARSC Milwaukee 2007-05-044 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 it’s their turn to be copied Some tapes may degrade before it’s their turn to be copied

5. Richard L. Hess ARSC Milwaukee 2007-05-045 Conceptual Timeline

6. Richard L. Hess ARSC Milwaukee 2007-05-046 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

7. Richard L. Hess ARSC Milwaukee 2007-05-047 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

8. Richard L. Hess ARSC Milwaukee 2007-05-048 General degradation modes Tape pack defects Tape pack defects –Spoking –Folded wraps –Popped strands Reel defects Reel defects –Weak hubs –Warped flanges

9. Richard L. Hess ARSC Milwaukee 2007-05-049 Acetate base film 1935–1972 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

10. Richard L. Hess ARSC Milwaukee 2007-05-0410 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

11. Richard L. Hess ARSC Milwaukee 2007-05-0411 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 1943–1972 PVC was made 1943–1972 Paper was made 1940s–1950s Paper was made 1940s–1950s

12. Richard L. Hess ARSC Milwaukee 2007-05-0412 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

13. Richard L. Hess ARSC Milwaukee 2007-05-0413 Binder failures  Soft Binder Syndrome (SBS)  Sticky Shed Syndrome (SSS)  Pinning / Blocking  Binder-base adhesion failure

14. Richard L. Hess ARSC Milwaukee 2007-05-0414 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 

15. Richard L. Hess ARSC Milwaukee 2007-05-0415 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

16. Richard L. Hess ARSC Milwaukee 2007-05-0416 Soft Binder Syndrome T g 3M 175 – Currently T g ≈ +8°C (46°F) 3M 175 – Currently T g ≈ +8°C (46°F) One reel of 175 did not immediately respond at about 38°F (3°F), but did after two days of cold soak One reel of 175 did not immediately respond at about 38°F (3°F), 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

17. Richard L. Hess ARSC Milwaukee 2007-05-0417 Soft Binder Syndrome Solution Since the T g has become lower Since the T g has become lower It’s difficult to raise the T g It’s 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…

18. Richard L. Hess ARSC Milwaukee 2007-05-0418 Soft Binder Syndrome Solution

19. Richard L. Hess ARSC Milwaukee 2007-05-0419 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

20. Richard L. Hess ARSC Milwaukee 2007-05-0420 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

21. Richard L. Hess ARSC Milwaukee 2007-05-0421 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

22. Richard L. Hess ARSC Milwaukee 2007-05-0422 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 

23. Richard L. Hess ARSC Milwaukee 2007-05-0423 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.

24. Richard L. Hess ARSC Milwaukee 2007-05-0424 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 separate—pull-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.”

25. Richard L. Hess ARSC Milwaukee 2007-05-0425 Pinning / Blocking Binder adheres to next layer’s back Binder adheres to next layer’s 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 +4°C with silica gel packet 

26. Richard L. Hess ARSC Milwaukee 2007-05-0426 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 

27. Richard L. Hess ARSC Milwaukee 2007-05-0427 Factors influencing degradation  Tape formulation / component selection  Component degradation / failure  Manufacturing defects / tolerances  Storage conditions  Playback without proper conditioning  Playback on defective equipment

28. Richard L. Hess ARSC Milwaukee 2007-05-0428 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

29. Richard L. Hess ARSC Milwaukee 2007-05-0429 Anticipated lifetimes Manufacturer design life: 10–20 years Manufacturer design life: 10–20 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

30. Richard L. Hess ARSC Milwaukee 2007-05-0430 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

31. Richard L. Hess ARSC Milwaukee 2007-05-0431 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

32. Richard L. Hess ARSC Milwaukee 2007-05-0432 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

33. Richard L. Hess ARSC Milwaukee 2007-05-0433 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

34. Richard L. Hess ARSC Milwaukee 2007-05-0434 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? Don’t delay starting in earnest Don’t delay starting in earnest Do it now … now … now … now Do it now … now … now … now

35. Richard L. Hess ARSC Milwaukee 2007-05-0435 When ? Now

36. Richard L. Hess ARSC Milwaukee 2007-05-0436 What is in typical archives? GOODFilesCDsBADReelsRecordsUGLYDATsCassettesPCM-F1Minidisc

37. Richard L. Hess ARSC Milwaukee 2007-05-0437 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 Don’t assume any of these formats will be playable in 10-20 years Don’t assume any of these formats will be playable in 10-20 years Transfer NOW! Transfer NOW!

38. Richard L. Hess ARSC Milwaukee 2007-05-0438 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

39. Richard L. Hess ARSC Milwaukee 2007-05-0439 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

40. Richard L. Hess ARSC Milwaukee 2007-05-0440 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

41. Richard L. Hess ARSC Milwaukee 2007-05-0441 Topology Varied technologies Varied technologies –Spinning Disk –LTO-3 tape Metadata Metadata –Rich index of what is in archive

42. Richard L. Hess ARSC Milwaukee 2007-05-0442 Security Multiple disk copies Multiple disk copies Multiple tape copies Multiple tape copies Off-site storage Off-site storage Don’t forget storage on different plates, away from faults Don’t forget storage on different plates, away from faults

43. Richard L. Hess ARSC Milwaukee 2007-05-0443 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

44. Richard L. Hess ARSC Milwaukee 2007-05-0444 What about other formats? Don’t try and mix formats, but multiple bit/sample rates may be acceptable Don’t 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, don’t rely on long-term codec availability Convert to the archive format if other formats are ingested, don’t rely on long-term codec availability

45. Richard L. Hess ARSC Milwaukee 2007-05-0445 Storage overview Archival storage must be… Archival storage must be… –Understood –Funded –Designed –Organized –Populated –Managed in perpetuity

46. Richard L. Hess ARSC Milwaukee 2007-05-0446 Storage management Don’t risk losing audio material Don’t risk losing audio material Don’t trust dedicated formats long term Don’t 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

47. Richard L. Hess ARSC Milwaukee 2007-05-0447 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 can’t play the tape doesn’t mean it’s not recoverable. Just because you can’t play the tape doesn’t mean it’s not recoverable. Tapes are not getting better with age. Tapes are not getting better with age.