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Lighter edge-shedding another possible degradation modality

Filed under: project notes,Tape Aging — 2011-03-05 by Richard L. Hess — Last Edit 2011-03-05 by Richard L. Hess

We have seen some tapes which cannot be baked and others that did not need baking and could be treated in an easier way. Our degrading tapes page has been updated with a section on Lighter edge-shedding. This also includes a description of a simple tape-wiping process.


Updates posted for “winding tapes for long-term storage”

Filed under: archival practices,reels,storage-care-handling,Tape Aging,video — 2011-02-17 by Richard L. Hess — Last Edit 2011-02-17 by Richard L. Hess

There was yet another discussion about winding tapes for long term storage. This time it was on the Society of American Archivists list. While it was focused on VHS tapes, where it was decided that it was more important not to leave the tape in the middle with active content exposed, some discussions of the mechanics arose and I have added them as comments to the original post, which is available here.


Winding tapes for long-term storage—a quandary

Filed under: archival practices,storage-care-handling — 2008-02-15 by Richard L. Hess — Last Edit 2011-02-17 by Richard L. Hess

In 2006, I wrote a blog post (here) called “Let Sleeping Tapes Lie: What to do with poorly wound tapes”. For years, tape experts have been suggesting that it is not as good an idea to rewind tapes as was originally thought. This was partially based on the fact that most rewinding in archives was done on the oldest, junkiest machines so as to not wear out the good machines. Unless rewinding is done on high-quality tape transports, it is indeed counter-productive.

We continue to receive poorly wound tapes and are able to play them successfully. So why the quandary now? The reason is that I read portions of another Bharat Bhushan book, Mechanics and Reliability of Flexible Magnetic Media, 2nd Edition, New York, Springer, 2000. Referring to several research papers he makes a compelling case that tapes should be rewound annually if subject to storage environment fluctuations and every 3.5 years if kept in a climate controlled storage area. (more…)


IASA TC04 Guidelines on the Production and Preservation of Digital Audio Objects available online.

Filed under: archival practices,cassettes,computer/data,digital,education,history,reels,Tape Aging — 2010-10-08 by Richard L. Hess — Last Edit 2010-10-08 by Richard L. Hess

The International Association of Sound and Audiovisual Archives (IASA) has released their landmark Guidelines on the Production and Preservation of Digital Audio Objects as a free web (HTML) edition, available here.

I provided some information for the listing of tape equalizations, and I find the compiled table (here) most useful.

Thanks to Kevin Bradley and the IASA team for their work in making this available. If you want a PDF copy, join IASA and it’s available.


Cassette equalization redo

Filed under: cassettes,history,Tape Aging — Richard L. Hess — Last Edit 2010-10-08 by Richard L. Hess

There has been much discussion on some web fora about the differences between different brands’ cassette equalization standards.

As I stated here in 2006, there is a 4 dB ambiguity at 16 kHz.

Many things conspire to make this 4 dB ambiguity essentially meaningless in a generally low-fi medium. The only reason I’m mentioning this now is that I’ve been bombarded with email from more than one participant in this discussion and apparently there may be some editorial judgment attached to what is posted.

Jay McKnight has graciously permitted my posting of his comments to me: (more…)


Compander-type Noise Reduction Systems

Filed under: archive operations,audio,history,project notes — 2010-02-20 by Richard L. Hess — Last Edit 2010-05-01 by Richard L. Hess

Note: This information has been incorporated into this page which contains a more in-depth discussion.

I received an urgent phone call yesterday from a man who had digitized several reels of 2″ 24-track analog recordings that he wished to re-mix.

The tapes were originally recorded in about 1978-1979 and he said that he needed them to have Dolby C noise-reduction processing applied to the files.

I did a bit of research, as that did not sound correct from an historic point of view.

Here is an approximate chronology of the major noise-reduction systems and their dates of introduction: (more…)


New Degrading Tapes page

Filed under: project notes,Tape Aging — 2009-01-30 by Richard L. Hess — Last Edit 2009-11-06 by Richard L. Hess

We have pulled the list of degrading analog audio tapes out of the blog postings (which age) and put this information into the Formats hierarchy under Analog Audio Tapes, click here. Please note that we have fudged the hierarchy by starting the title with a hyphen, so it sorts to the top of the Analog Audio Tape grouping, above 0.15″ cassettes.

We hope to update this as we come across more types. January 2009 was, sadly, fruitful in finding at least some batch(es) of two tapes from 1990 (Agfa PEM 526) and 2003 (Emtec SM911) are degrading. The Emtec SM911 was thought to be more-or-less immune from this disease. As of this writing, it has been confirmed that batch number B0134007 was involved.


Success with squealing Shamrock 031 tape

Filed under: project notes,Racal Store 4DS,Tape Aging — 2007-11-08 by Richard L. Hess — Last Edit 2009-11-06 by Richard L. Hess

I spent days trying to get Shamrock 031 to play without much success. Since this is an Ampex factory budget brand (probably non-spec premium tape) I thought that it might be suffering from Sticky Shed Syndrome. I baked it for 12 hours and it still squealed. I then tried my usually successful cold playing technique and it still squealed. Cold playing has worked successfully with 3M 175 and Sony PR-150.

I was getting rather frustrated and since it was a four-track tape and one of the techniques that is supposed to reduce squeal is to play the tape faster, I dragged out my Racal Store 4DS instrumentation recorder which has a 75,000 Hz bandwidth at 15 in/s and played it at 15 in/s and digitized it at 88,200 samples per second. After slowing it down 4x and ending up with a 10 kHz bandwidth (which I subsequently truncated to 5 kHz since there was no useful information above that, but lots of noise–same as the non-squealing portion of the real-time transfers on a Studer A810).

 Racal Store 4DS playing formerly squealing Shamrock tape

(more…)


Back-coat turning to powder

Filed under: project notes,Tape Aging — 2009-01-30 by Richard L. Hess — Last Edit 2009-11-06 by Richard L. Hess

We have just seen a modification on the Sticky Shed Syndrome (SSS) failure mode. This is a case where the back-coat of the tape is turning to powder. The oxide was brown but yet it left a black, non-sticky accumulation of powder on the reproduce head. This accumulation would drastically reduce the high frequency response of the system due to spacing loss. We did bake the tape and we’re not sure that helped significantly, although it did not appear to make the problem worse. We would NOT recommend baking these tapes in the future. Ultimately, Pellon wiping of the mag coat during transfer after several pre-wipes for the length of the tape solved this.

Agfa PEM-526 exhibited this odd behaviour. The tape was recorded in 1990.

There is also a discussion about PEM-469 showing similar behaviour here.

For a current list of degrading analog tapes, click here.


MD5 Checksums bring peace of mind

Filed under: archival practices,data storage — 2008-05-04 by Richard L. Hess — Last Edit 2009-11-03 by Richard L. Hess

If you ever worry about a bit error happening to your files and not finding out about it, you should use MD5 checksums (or some similar method) to be able to verify that the file has not changed.

The general theory behind a checksum (or “Message Digest” = “MD”) is that it provides a unique 128-bit number for each and every file, based on its content. If one bit changes, the MD5 checksum (sometimes called “hash”) changes. The checksum is repeatable, does not permit discovery of two different files that produce the same checksum, and is non-reversible (i.e. you can’t create the content from the checksum). (more…)


Long-term stability of different batches of Ampex 456 – a guest article by Gary Galo

Filed under: reels,Tape Aging — 2009-10-21 by Gary Galo — Last Edit 2009-10-21 by Richard L. Hess

Here’s some info that might be useful concerning which batches of Ampex 456 are good and which have sticky shed problems.

I recently unearthed 26 brand new 10 1/2-inch reels of 456 from 8 different batches. I checked one reel from each batch by playing them back and forth at 15ips (I only played the bad reels in one direction – that was enough!). The following batches were bad:

(more…)


Zoom H2 line input

Filed under: archival practices,computer audio,live sound and recording,recording/mastering — 2009-04-13 by Richard L. Hess — Last Edit 2009-07-27 by Richard L. Hess

The Zoom H2 HandyCorder is perhaps the lowest-cost digital recorder on the market that provides reasonable and useful results. While I have a Sound Devices 722 for my more serious work, I bought the Zoom to test it out to see if it could be part of a simple tape digitization system for archives on a budget who wish to do the work themselves. It does this reasonably well.

As with much equipment–and especially with lower-cost equipment–the performance specifications and the actual operational data is not published. There are reports of the H2 clipping on the line inputs in some of the reviews and it appears that a lack of understanding how the inputs were configured exacerbated that situation.

There is nothing wrong with the line inputs on the H2. BUT there are some caveats: (more…)


40th Anniversary of Apollo 11 Moonwalk and the loss of data

Filed under: archival practices,data storage,history,oral history,video — 2009-07-17 by Richard L. Hess — Last Edit 2009-07-17 by Richard L. Hess

There has been much discussion over the last few years about finding and saving original tapes of the Apollo 11 Moonwalk videos downlinked from the moon. There is also an exciting project going on to restore and digitize the Lunar Orbiter tapes from more than 40 years ago.

The Lunar Orbiter tape digitization folks have just posted a commentary that bears reading by all archivists who are holding tapes. You may link to it here. The main site is www.moonviews.com

NASA, in their press conference yesterday held at The Newseum, admitted that the original 14-track 1-inch instrumentation (IRIG) tapes that contained the slow-scan video direct from the moon were most likely recycled and reused for later missions. Apparently, over 350,000 reels of instrumentation tape were recycled by NASA over time. No one apparently thought to preserve the 45-odd reels of the original moon walk. (more…)


Kodak Durol triacetate tape with bad vinegar syndrome

Filed under: project notes,Studer A807,Tape Aging — 2009-04-07 by Richard L. Hess — Last Edit 2009-04-07 by

I recently received two 7-inch reels of Kodak Type 31A Triacetate tape (1250 feet, Durol Base) that smelled of vinegar even before I got the envelope open.

These tapes were badly warped due, most likely, to the vinegar-syndrome induced differential shrinkage. Other factors may have been poor winding during long-term storage (I had received them after several attempts to play them on another machine). (more…)


Images of Scotch (3M) tape boxes available

Filed under: history,reels,Tape Aging — 2009-02-04 by Richard L. Hess — Last Edit 2009-02-04 by

I was interested in the progression of the Scotch/3M tape boxes over the years, especially after someone contacted me because his father was in the picture on some of the 1960s tape boxes.

(more…)


Tape Degradation—Introduction

Filed under: storage-care-handling,Tape Aging — 2006-03-09 by Richard L. Hess — Last Edit 2009-01-30 by

This is a general article to provide some information on the subject. More should follow.

For a current list of degrading analog tapes, click here.

There are multiple modes of degradation and it depends on the type of tape.

Acetate Tape

  • Degrades through drying out (hydration has helped in some cases)
  • Breakdown of the base through “vinegar syndrome” and possibly leading to total decompostion (although that has not been seen for tapes on any large scale)
  • Damage from heat
  • Damage from mold/fungus
  • Loss of Lubricant is probably rare in acetate tapes. Few examples of it have been found.
  • Freezing acetate tape (especially) is considered bad as many of the formulations included fatty-acid lubricants. Remember, this was from the 1940s and 1950s and one of the best lubricants of the era was sperm oil.

Polyester tape

  • Binder hydrolysis (or sticky shed syndrome [SSS]) is the largest challenge faced with tapes from the 1970s-1990s. This can be partially reversed through incubation or heat treatment. While this link may not be complete, it is a great introduction.
  • Loss of Lubricant (LoL) can be severe and can possibly be combined with binder hydroysis.
  • Freezing is also not recommended for polyester tapes due to the potential of that tape also containing fatty-acid lubricants.

Obviously all tapes can suffer from mechanical damage and poor winds.

I expect to be discussing aspects of this in greater depth, but it is a complex subject and contradictory reports have been generated.


Wet playing of reel tapes with Loss of Lubricant—A guest article by Marie O’Connell

Filed under: Tape Aging — Marie O'Connell — Last Edit 2009-01-30 by

This is the first of many guest articles here. Thanks to Marie for agreeing to share her wonderful work in playing tapes that did not respond to baking. SSS=Sticky Shed Syndrome, LoL = Loss of Lubricant
For a current list of degrading analog tapes, click here.–Richard

There has been a lot of interest in this issue recently and I’ve answered several people privately. Hopefully this location will make the work more accessible to all who are interested.

overall view

The general appearance of the Mark II. As you can see, I had the luxury of being surrounded by these great machines and so we sacrificed one with all the adaptations done by a great technician by the name of Noel McGinnity – we both agreed we still wanted it to look like an almost regular Studer! All the tubing has been adapted to withstand isopropyl alcohol and the IV drip bag does not leak.

I began working at Sound Archives/Nga Taonga Korero, which is a wholly owned subsidary of Radio New Zealand in 1994. My task was to preserve and digitize the entire NZ Composer’s collection to begin with. I was taught my skills “on the job” but was lucky enough to have the wisdom & know it all of several older broadcasting technicians at my fingertips.

(more…)


Sticky Shed & Loss of Lubricant

Filed under: archival practices,Tape Aging — 2006-05-17 by Richard L. Hess — Last Edit 2009-01-30 by

This post has been updated as: http://richardhess.com/notes/2007/03/21/soft-binder-syndrome-and-sticky-shed-syndrome/

For a current list of degrading analog tapes, click here.

For several years, we have been discussing the differences between Sticky Shed Syndrome (SSS) and Loss of Lubricant (LoL).

Recent work in which I’m participating seems to indicate that what we thought was happening in both instances may not be really what is happening.

For now, the continued recommendation is to bake tapes for which baking works. These include:
Agfa (pre-1990): PEM 468, PEM 469
Ampex/Quantegy (1970s-1980s): 406, 407, 456, 457
Note: Recent reports indicate that these problems may exist in tapes  made in the 1990s
and later, even under the Quantegy name.
Audiotape/Capitol (early 1980s): Q15
Note: This tape may or may not respond to baking. Some tests will be conducted soon.
Scotch/3M: 226, 227, 806, 807, 808, 809

If these are squealing and leaving deposits, they should be baked (at your own risk). The Ampex patent for baking tapes can be found here.

The classic test for determining if a tape is suffering from LoL has been to bake it and see that baking fails. The assumption has then been that it is loss of lubricant. This test, however,  may exacerbate the condition and it is not recommended to bake suspected LoL tapes.

Tapes which appear to be suffering from LoL include:
Scotch/3M: 175 and Melody 169 (a seconds brand of Scotch)
Sony: PR-150
Pyral: (type numbers unknown for this French tape)

We have seen cassette tapes also suffering from LoL.

There are several ways to address playing LoL tapes, but, for the moment, we are not prepared to publish anything definitive beyond Marie O’Connell’s tried and true method shown here.


The beginning of 3M 175 squeal ?

Filed under: Tape Aging — 2006-07-12 by Richard L. Hess — Last Edit 2009-01-30 by

UPDATE: March 2008…Cold playback (see this article) seems to work with the two tapes mentioned in this article, 3M 175 and Sony PR-150. We’ve had confirmation from several sources who have tried it.

For a current list of degrading analog tapes, click here.

Fellow restorer Doug Pomeroy sent me a photocopy of Herman Burstein’s “Tape Guide” article from the May 1977 issue of “Audio” magazine. Robert Coe of Manchester, CT, wrote in saying “…some of these [Scotch 175] tapes have developed a high frequency chatter or squeal which is mechanical and can be stopped by rubbing the tape with a light coating of talcum powder. The squeal only occurs on the Scotch 175 tape even when used with several different brands of tape machine.” Burstein replied, “Yes, I’ve heard other complaints about squeal, sometimes involving Scotch tape which is not surprising in view of 3M’s large share of the market, but yours is the first complaint about 175 tape.” He went on to say that another 3M tape exhibited this but it was limited to the batch and 3M replaced it.

We do not recommend the talcum powder approach as it overall has proven to be a bad idea since it gums up the machines and increases spacing loss more than other solutions.

Doug is currently having a joyous bout with 175 but Art Shifrin apparently has a proprietary mechanical fix to the tape deck that allows playing 3M 175.

We are researching more about 175 and hope to have updates. The use of decamethylcyclopentasiloxane (D5 or cyclomethicone) has had mixed results with 175 and Sony PR-150, another known squealer.


Soft Binder Syndrome and Sticky Shed Syndrome

Filed under: storage-care-handling,Tape Aging — 2007-03-21 by Richard L. Hess — Last Edit 2009-01-30 by

For a current list of degrading analog tapes, click here.

For several years, we have been discussing the differences between Sticky Shed Syndrome (SSS) and Loss of Lubricant (LoL). It appears from my latest research (presented at the 2006 Audio Engineering Society’s 121st Convention in San Francisco in October) that LoL does not really factor into the equation for most tapes and that an overarching failure mode is Soft Binder Syndrome, or SBS. Sticky Shed Syndrome appears to be a subset of SBS. (more…)


Another way to identify a tape with Sticky Shed Syndrome (SSS)

Filed under: archival practices,reels,Tape Aging — 2008-08-22 by Richard L. Hess — Last Edit 2009-01-30 by

For a current list of degrading analog tapes, click here.

Teaching people how to identify tapes that are suffering from sticky shed syndrome is often difficult.

I would like to propose that a careful inspection of how the tape comes off the pack may be a good way. Please provide comments as to how it’s working for you.

The tape should come off the tape pack at a precise tangent to the tape. If the tape starts to adhere and not pull off straight, that is a sure sign that the tape needs baking.

Of course, don’t bake acetate tapes even if they show this indicator, but on the last batch of questionable SSS tapes, I’ve been looking at this and it’s a fair indicator, and it seems to show at the outer edge of the pack.

More than one “test” or “factor” is needed to be sure, but this one is looking good.

Another almost sure sign of SSS is brown oxide and black back-coat.


ARSC Journal Tape Degradation article available online

Filed under: archive operations,audio,computer/data,Tape Aging,video — 2009-01-03 by Richard L. Hess — Last Edit 2009-01-03 by

My paper on “Tape Degradation Factors and Challenges in Predicting Tape Life” that was published in the Fall 2008 issue of the ARSC Journal is now available online. Click here.


Magnetic Tape Splicing

Filed under: archive operations,cassettes,reels — 2008-01-07 by Richard L. Hess — Last Edit 2008-06-05 by

I received an email asking me to discuss tape splicing. Most of my work is now repairing old splices so I try and butt them together as best I can in an Edi-Tall block and use the blue Quantegy splicing tape (which will become harder to find with Quantegy exiting the business). I will not be evaluating a replacement for several years as I bought a large supply a few years ago. (more…)


Project Notes: Advanced oxide delamination of a cassette

Filed under: cassettes,project notes,Tape Aging — 2006-03-31 by Richard L. Hess — Last Edit 2008-06-05 by

A client phoned me and said a cassette he was playing started to shed in his machine and he stopped and took it out. He sent it to me and as I pulled a little bit of clear leader out of the middle of the tape, this is what I found:

flaky_tape_01

Notice how the complete strips of oxide exist on their own, independent of the clear “leader” to which they previously were attached. (more…)


Transfer Recommendations

Filed under: archival practices,recording/mastering — 2006-03-08 by Richard L. Hess — Last Edit 2008-06-05 by

Remember, this transfer that you (or I) are about to undertake may be the last time (and hopefully the best time) that the original is transferred. Here are some suggestions: (more…)


Aligning a tape recorder

Filed under: archival practices,cassettes,recording/mastering,reels — 2008-02-02 by Richard L. Hess — Last Edit 2008-06-03 by

It seems some people new to tape are confused over how to align a tape recorder. This is the abbreviated version.

If you want to record on a tape recorder (and I do not recommend doing that these days as you’re just generating more tapes that will need to be transferred later) the first thing to do is get the playback correct.

  1. CLEAN the machine. (more…)

DSS and other compressed digital files in an oral history archive

Filed under: archival practices,computer audio,dss — 2006-08-17 by Richard L. Hess — Last Edit 2008-06-03 by

With budget limitations, it appears that oral histories are being recorded with little thought to their long-term preservation. While this appears to have been the case in the past as well, with purchasing agents buying the cheapest white-box tape that they could find, continuing this into the digital age needs to be reconsidered.

The cost savings in using bargain-basement digital speech recorders are offset by the labour required to reformat these files upon their receipt by an archive and also the fidelity of the recording suffers, and with fidelity, intelligibility also suffers.

DSS was an industry standard agreed upon by Olympus, Grundig, and Philips in 1994. (more…)


Hard disk formats for interchange

Filed under: data storage,storage-care-handling,tools — 2008-02-03 by Richard L. Hess — Last Edit 2008-06-03 by

The question of how to format hard disks (i.e. what file system to use on them) for easy interchange is another FAQ. A recent experience brought home the fact that it is more complex than one might hope. The computer industry is headed towards universal readability, but it is not there yet. The most-able-to-be-read-and-written format appears to be FAT32, although my friend Eric Jacobs makes the point that NTFS is a more robust hard disk file system, and I have to agree. (more…)


Can I destroy my originals after I digitize them?

Filed under: archival practices — 2007-09-20 by Richard L. Hess — Last Edit 2008-05-10 by

Jill Hurst-Wahl in her excellent blog “Digitization 101” asks this question and provides some good answers with reasons. You can read it here.


Digital storage file systems and topologies

Filed under: archival practices,audio,data storage,video — 2008-03-04 by Richard L. Hess — Last Edit 2008-04-15 by

Once again, an interesting post on Jill Hurst-Wahl’s Digitization 101 Blog. She started by discussing tape backup issues. In the comments, I discussed my solution of using multiple spinning disks. Another commenter, Ike, provided an extensive review of file system options and his opinions on what works (and doesn’t) for long-term storage. Ike’s comment is fascinating and has lots of food for thought. Here is the post. (more…)


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