Tape Problems

There are a lot of sources for vintage tape including eBay, garage sales and your own garage. These tapes can be anywhere up to 50 years old and will likely be shedding, the deposit of oxide onto the tape heads.

The first tape to be available from the 1950s to the mid 1980s was a shade of brown, ranging from light to dark brown, where both sides of the tape is approximately the same color. Once side is duller than the other and faces the tape heads, the other side is shiny and faces away from the heads. If you’re familiar with cassette tapes, consider this tape to be of ‘normal’ bias. It’s a decent quality tape good for voice or music recording, but for the best quality recordings, use later vintage back-coated tape.

Back coated tape was introduced in the mid 1970s, and is the equivalent to chrome dioxide cassette tapes, with a higher tape output, better signal to noise ratio, extended frequency response and lower distortion. By the late 1970s, any high end recording was made on back-coated tape, but by the mid 1980s, some problems were discovered with back coated tape. More on this below.

A typical non back coated tape, medium brown in color (can also be dark gray), showing significant shedding, where oxide has come off the tape in chunks
A typical non back coated tape, medium brown in color (can also be dark gray), showing significant shedding, where oxide has come off the tape in chunks

Non back-coated tape will deposit light to medium brown oxide on the tape heads and guides and rollers, so regular cleaning of the tape path is necessary. Recording studios generally cleaned the tape path before every recording session and after every reel of tape played, so this is a good practice at home as well. You cannot damage tape heads or the tape path with cotton swabs and appropriate tape cleaner or isopropyl alcohol that is over 99% pure. Note however that isopropyl alcohol CAN damage older rubber on pinch rollers. More on this in the tech section regarding cleaning the tape path.

Back coated tape has its own special problems. ‘Sticky shed,’ also known as ‘SSS’ developed a few years after it was sold. We’ve modified this term a bit to ‘SSS’ Syndrome, which stands for ‘Sticky Shed Squeal’ syndrome. Tapes may show one or all of these symptoms. Let’s look at these three issues:

Typical back coated tape, brown on the oxide side, black or charcoal gray on the back side
Typical back coated tape, brown on the oxide side, black or charcoal gray on the back side

Shedding Tape: As with the non back coated tape, back coated tape can shed, and some reels will shed a lot. We’ve seen a few tapes that can literally coat the tape heads and path within 30 seconds of playing with massive amounts of oxide coming off the tape. This can reduce the high frequency output of one or more channels, and in extreme cases, will completely kill the sound output. You stop the tape, look at the heads, and see the oxide all over the tape heads. You clean the heads, start the tape again, and before the reel is finished, the heads are covered in oxide again.

Sticky Tape: If you slide a reel of tape onto a pen or pencil and pull downwards on the tape end, the tape should unroll freely, and end up in a pile at your feet. If a back coated tape becomes sticky, the layers of tape will stick to each other, and the tape will not unroll. In extreme cases, the tape will pull off oxide from the adjacent layer of tape, causing dead spots (dropouts) in the tape, rendering it useless.

An extreme example of shedding tape
An extreme example of shedding tape

Squealing Tape: Within minutes (seconds, sometimes), you’ll get terrible distortion through your speakers along with a squealing sound. You turn the volume off on your amplifier, and you then hear the squeal coming as a mechanical noise from the tape transport itself. By moving the tape gently as it is playing, you’ll hear the squealing sound change. Pull the tape off the tape path, and you won’t generally see any oxide buildup on the tape heads or tape path, and you’re left scratching your head as to why your tape deck is squealing. Along with the squealing, you may find loss of high frequency response on one or both channels, and again, the tape heads and path look clean.

The problem with squealing tape is that it is the tape binder (glue) that holds the oxide to the tape base itself that is shedding, putting an invisible layer onto the tape path. This binder causes massive amounts of friction, and rewind or fast forward either won’t work or is very slow. Don’t panic! Clean the entire tape path, and rewind the tape completely. Then clean the tape path again to remove residue left in the tape path by rewinding the tape. In extreme cases, you may need to apply significant amounts of pressure on the tape heads to remove this tape binder in order to get your high frequency response back.

Fixing SSS tape

There is a cure! Note that this fix only applies to back coated tape and will damage normal tape. The solution is called ‘tape baking’. SSS tape problems are caused by the tape absorbing water vapor over time.

I have baked several hundred back coated SSS tapes successfully, and to date, I’ve only had two reels of tape that could not be baked to eliminate the SSS syndrome. Depending on the articles you read online, the baking time ranges from 6 to 24 hours, and with my own experimentation, I’ve found the following:

  • it appears that most cases of SSS syndrome can be solved by baking a tape 12-24 hours. I’ve found that 6-8 hours isn’t enough to rid many tapes of the problems.
  • it seems that you cannot overbake a tape, since you’re simply evaporating water vapor out of the tape. I’ve accidentally baked tapes for as long as 48 hours, and the tapes continued to work fine
  • If a tape continues to display SSS symptoms after a first baking, there’s no harm in trying a second round of baking, and even a third. One of the aforementioned problematic reels of tape was baked three times here. While it didn’t solve the SSS syndrome completely, it did allow me to transfer the tape to CD successfully, and then I threw the tape out.
  • it is a really good idea to bake all used back coated tape prior to using it. The exception is tape made post 2000, as the SSS problems were solved by that time. If however you’ve gotten yourself a box of 20 year+ old back coated tape, bake it all prior to playing it on your machine.
Tape Baking Equipment

If you have found a cache of new old stock tape, it can still develop SSS symptoms even though it’s never been used, and still is in the cellophane package. It’s fine to bake a tape while still in the sealed cellophane wrapping, the water vapor wil evaporate right through the packaging.

NOTE: DO NOT BAKE non-back coated tape! Baking will destroy the tape, rendering it useless.

Equipment: A standard food dehydrator. This raises the tape temperature to 110-140 degrees Fahrenheit and evaporates the absorbed water and the tape will usually work as new.

Take the reel of tape, whether it’s on a plastic or metal reel, and place it on one of the food dehydrator trays. You can bake several tapes at once, and you can also put tape pancakes right onto a tray. All you’re doing is increasing the temperature of the tape itself to 100-140 degrees to evaporate the water that has been absorbed into the tape itself. Once you have baked the tape, take it out of the food dehydrator, let it cool to room temperature, put it on your machine, and see if the SSS syndrome(s) are cured.

Note: DO NOT bake a tape in your oven! Most ovens do not go below 200 degrees, and even if your oven has a setting of 150 degrees, the thermostat may not be accurate, and you’ll destroy your tape.

I have found that most tapes will work fine for many uses after baking. This counters most articles online that say to copy the recorded material onto another medium once you’ve baked the tape, the then throw the reel away. I use a number of tapes daily on my bench that I have baked a number of years ago, but I do throw out tapes that continue to develop SSS syndromes after multiple bakings.

READ MORE: All About Tape