Video – Identifying Audio Reels with Binder Hydrolysis


Transcript of the video "Identifying Audio Reels with Binder Hydrolysis"

Video length: 00:03:19

Joe Iraci, Senior Conservation Scientist: "One of the most significant problems with magnetic tapes in collections is degradation of the binder layer or the layer that holds the magnetic particles onto the tape base.

This degradation occurs via hydrolysis or a chemical reaction involving water molecules.

When the binder layer degrades in this way, the tape becomes sticky and the binder sheds because it no longer adheres to the tape base."

[Cross-section of audio reel tape, indicating various areas of the tape near the labels. Label text: Cross-section of a typical audio reel tape: magnetic particle; lubricant reservoir; binder layer; base layer and backcoat layer.]

Joe Iraci: "It is for these reasons that the degradation is often referred to as the sticky-shed syndrome."

The classic signs of a binder degradation problem are noticed when a tape is played. Binder material sheds and builds up on the parts of the playback equipment. This creates high friction and a squealing noise."

[Audio sample can be heard. Text: Audio Sample of Squealing Noise, Audio sample from AVAA]

Joe Iraci: "Playing a tape in this condition will often damage it beyond repair. Therefore, it is best to determine if this problem exists prior to playing a tape.

A non-destructive test to identify a binder degradation problem on reel tapes is the gravity test.

To perform the test, the loose end from a reel of tape is suspended. A tape without binder degradation will freely unwind from the reel without much resistance."

[A demonstration of the gravity test is presented with both good and poor conditioned tape]

Joe Iraci: "On the other hand, when performing the same test on tape with binder degradation, there is some noticeable adhesion between the tape layers, and the tape does not unwind without some resistance.

In order words, there is a slight amount of stickiness.

An additional test is to examine if the binder sheds off the plastic base of the tape.

This is a destructive test, but only a small portion of the tape is required."

[A demonstration of the destructive test is presented]

Joe Iraci: "To perform the test, a strand of tape is rolled between the fingers with the binder side pointing outwards. If you are unsure about which side is the binder side, perform the test on both sides. A tape with binder degradation will shed off the plastic base rather easily.

Some treatments are available that will give you an opportunity to salvage the tape so that it can be played and digitized.

However, in order to ensure maximum success in restoring the tape, treatments for the binder hydrolysis problem should only be performed by an expert in tape restoration."

[Text on screen: For more information, please see Canadian Conservation Institute Technical Bulletin 30, The Digitization of Audio Tapes, and Technical Bulletin 27 Remedies for Deteriorated or Damaged Modern Information Carriers.

Acknowledgements: AVAA: The AV Artifact Atlas (]

[Canadian Conservation Institute signature and Canada wordmark]

This video demonstrates tests used to identify the presence of binder hydrolysis on audio tape reels. This video was created by the Canadian Conservation Institute.

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