Tape Restoration

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The Sticky Sheds

Many open-reel tapes manufactured in the 1970's and 1980's have become unplayable due to binder breakdown; the surface of the tape has become gummy and it sticks to the heads and fixed guides of the tape transport, squealing, jerking and, in extreme cases, slowing down or stopping the tape transport. This problem has become known as the "sticky sheds". Its cause is hydrolysis, or absorption of moisture by the tape oxide binder over time.

Fortunately, this problem is fixable by gentle heating ("baking") of the tape for several hours. Once a tape is properly "baked", it remains playable for about a month under normal storage conditions; ample time in which to transfer it to the medium of your choice.

I have the proper equipment to "bake" analog open-reel tapes. In the case of 1/4" mono or stereo tapes at speeds up to 15 ips, I can also do any subsequent transfer you might wish.

Other tape problems

Tapes can also suffer from lubricant breakdown, which leaves a white residue when the tape is run over the heads, as opposed to the dark residue of binder breakdown. It is a fairly rare problem, but fixing it requires careful cleaning of the tape and possibly applying fresh lubricant. Baking will not solve lubricant breakdown and may make it worse. Also, tapes with acetate backing [typical of many tapes from the 1950's and 1960's] should not be baked, as this will damage the backing.

Tapes from the 1950's and 1960's almost never suffer from hydrolysis. The different binder formulations used then are far less likely to absorb moisture. Rather, problems of deteriorating splices and acetate backing that has become deformed are much more common. In some cases, acetate tapes will suffer acetate breakdown, characterized by a vinegar-like smell. If this becomes advanced enough, the tape will become unplayable and cannot be salvaged. Any acetate tape in the early stages of acetate breakdown should be transferred to another medium as soon as possible.

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Archival Media Options

When a tape is being restored, the issue of what media to copy it to arises. Do we make a new analog tape copy or do we copy to a digital format? For an overview of those options, see my article, Archiving to CDR: some considerations.

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2005, Robert Auld


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