The effects of hydrolysis over great enough period of time, can cause weakening of the binder layer to the point where de-lamination from the substrate occurs. The problem often manifests itself by almost instant head clogs every few seconds, as the least disturbance of the weakened binder by the rotating scanner video heads results in a shedding of the oxide. In severe cases (especially where the tape has been exposed to water & not properly immediately treated), the oxide literally falls off the substrate, making for a horrific mess.
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Here the oxide has literally
flaked off the substrate. Note the now "transparent" tape and the
large flakes of oxide strewn about. Sadly, this was the only recording
of a wedding . |
Other causes are exposure to temperatures in excess of 130 deg f or below 5 deg f. The binder layer and substrate are made of disparate materials with a different coefficients of expansion/contraction. Excessive and repeated exposure to temperatures outside the norm, may result in almost immediate delamination, resulting in oxide shed. Improperly stored tapes that are damp and then "fast frozen", will literally tear the binder apart (not unlike our roads here in Maine come spring, where repeated freezing / re-freezing wreaks havoc). An asphalt paved road is very similar to a video tape, in the sense that the smooth paved surface corresponds to a tapes' binder layer, and the gravel base is analogous to the tapes' substrate. Not surprisingly, the same environmental processes that delaminate a roads' surface (read: potholes) also results in a damaged video tape.
Oxide shedding is a serious problem, as there is no known technique for repairing the malady. However, tape baking can make it's effects less pronounced (only if caught in the very early stages) before separation is visually evident, by reducing the stickiness and subsequent drag on the tape. Tape re-lubing can also often get a tape with a weakened binder layer to play without shedding off the oxide by reducing friction, just long enough for the transfer to be made.
Tapes exhibiting signs of oxide shedding without being properly prepared, should never be burnished. Unless the binder can be re-stabilized, the oxide layer on these tapes is extremely fragile and the least amount of force can tear it free. This is a case where often the cure is much worse than the ill.
Once a tape exhibits oxide literally falling off the substrate in either flakes or strips - or the machine transport get rapidly "gummed up" by the residue, it's sadly far too late... It's then the "All the Kings' Horses, and all the Kings' Men" scenario, as that tape will never play Video Again.....
This topic is closely related to oxide shedding, as well as the effects of hydrolysis and proper environmental storage conditions. In effect, it's the last and final breakdown stage of the tape.
During manufacture, the binder layer (usually made from a thin coating of polyurethane) is bonded to the substrate layer (usually polyester) thru a process of high temperature and pressure. (No.... the two layers are not "glued" together)...... The high temperature plus high pressure applied, literally forces the molecular bonds of both similar (but still slightly different) polymers together. This results in a strong yet extremely flexible bond... just ideal for the manufacture of both audio and video tape !
Though durable, thin and flexible, the molecular bonds are capable of being broken. Long term exposure to moisture (hydrolysis) or excessively high temperatures (the tape was left out in the sun or in the trunk of a car on a hot summers day) can break the bonds apart. Other common reasons are exposure to any solvent or a damp tape being instantly frozen, as is sometimes the case in the northern latitudes during the frigid winter months... The newly formed ice crystals tear the bonds apart.... When the bonds are broken, the binder layer containing the oxide or metal particles, separates from the substrate. The binder then either flakes off like confetti or may be dislodged in strips.
Once de-lamination has occurred, the tape & all it contains, is "history"......
Though the image degrades a varying amount each year, by the time 25 years or so have elapsed, more seriously than the image degradation is that the video tape is often now unplayable...... owing to mechanical breakdown of the tape itself. The video tape has sadly arrived at the end of it's useful life. All might not, yet be lost..... it can often be brought back from the grave ! It's not the "fountain of youth", but it will stabilize it at least long enough to make a good transfer. After baking, the transfer should be made as soon as possible - generally within a week at most. This area of the video restoration process is known as Tape Baking and is effective in about 95% of the cases where tapes are experiencing stickiness but have not yet progressed to the Oxide Shedding or Delamination stages !
The main problem with videotape is simply bad chemistry. This is really not a careless design flaw, but simply the the nature of the best technology yet available. Videotape is made from a base of polyester, which is coated with polyurethane. The coating acts as a binder (alas, it's name), trapping magnetic oxide particles -- the carriers of the magnetically encoded information -- within the tape. The binding system is fragile. High temperatures and humidity can wreak havoc with it, causing the urethane particles in the coating to react with water infiltration (a process known as hydrolysis), break free, and then migrate to the surface of the tape. The next time the tape is played, the oxide particles, no longer bound by the binder, peel or flake off, taking with them all evidence of anything previously recorded. The first symptom is clogged video heads.
Though all tape formulations are susceptible to the phenomenon, tapes manufactured between 1965 and 1985 are especially vulnerable to the "Sticky Tape Syndrome", where the tape turns in to a "sticky - gooey - mess" (not the exact scientific term, but nonetheless, an accurate descriptor...). The only hope of video recovery/restoration, is to literally attempt to bake out the moisture and thus harden & stabilize the binder.... The two most positive effects of tape baking is that it not only reduces the stickiness, but also hardens up the binder. Bad analogy: but sort of re-manufacturing the tape "on the fly" ....... Though the binder is hardened by the process, it still remain porous and weakened. Thus the effects of baking are only temporary , offering a small "window of opportunity" to effect a good transfer.
The tape is slowly baked in a temperature controlled electric convection oven for a time determined by the mass of the tape. Again, the procedure is not a permanent fix and the positive effects are often short lived, ranging from a few days to a couple of months before the effects of hydrolysis become apparent again. Should that fail, then the sad reality is that you waited too long to have it transferred. The tape and all that it might contain is lost forever, and will simply make a great paperweight.... (There's probably other applications for the tape, but none come quickly to mind.....)
Should "Sticky Tape" be encountered, immediately stop the machine and eject or remove the tape. To proceed further will not only permanently ruin the tape but will most likely lead to a severe jam requiring disassembly of the machine to remove the sticky tangled mess as well as another hour spent cleaning up the sticky residue from the tape path and pinch roller.
Read more on tape baking and Lab Ovens by clicking Here
Anywhere moisture or high humidity is present and the environment or the air contains even trace amounts of mold spores and other organic materials that serve as a "food" source, it's only a matter of time before mold spores decide that your video tape might be a nice place to live ! They perhaps "think" to themselves: "Hmmm..... A constant source of water - plenty of food and nice & dark in here.... This looks nice - Luxury accomodations ! - - - Think I'll move in and and start a large family !").... This is especially a problem in the tropical maritime climates where constant high humidity is the norm. You can't do much about airborne spores or other organics in the air, nor is it advisable to leave your tapes out in the sun. The only avenue left to stop mold development or growth is to cut off their water supply. Storing tapes in an environmentally controlled area or better yet, in an airtight bag with a small packet of silica gel placed inside is one solution. Another would be to purchase a vacume sealer. The moulds and fungi if left to grow, can eventually infiltrate into the binder layer given enough time, making their removal impossible without destroying the tape.
Cleanliness of a video tape is of prime importance. Even common household dust is a mixture of fragments of human skin, pet dander, minute particles of mineral or plant material, textile fibers, industrial smoke, grease from airborne sources , and plethora of other organic and inorganic materials. This chemical concoction often consists of the spores of countless moulds, fungi and micro-organisms which live on the organic material contained in the "dust". Much of the dirt is hygroscopic - meaning simply that it acts as a sponge. This increased moisture retention further encourages the growth of moulds, as well as increases the corrosiveness of airborne salts. It also serves to dramatically speed up the process of hydrolysis in tapes. (sort of a "double whammy")... The organic material often consists of fatty acids that promote the release of Palmetic and Hexadecanoic Acids that appear as a white substance on the tapes which must be removed before playback is attempted.
Properly cleaning an old video tape is best accomplished by gently passing both sides over Pellon ® tissue or a simple lint free fabric. Pellon is the trade name for a cloth like material, made of synthetic fiber, that was originally designed and produced to be used as a shirt collar stiffener, though it makes an ideal tape cleaner. Pellon ® (a trade-name) is low abrasive and non-dusting.
NOTE: If attempting to remove moulds yourself, beware that some moulds pose a serious and potentially FATAL health risk. While most, if not the vast majority of moulds are benign, some strains and embedded viruses are nothing short of DEADLY under the right conditions. Dried spores can easily be dislodged and become airborne, making inhalation possible. (Translation: This might NOT be a good thing for your longevity or general well being).... Thus always wear impermeable gloves and an approved Bio mask at the very minimum. Do not re-use the gloves and dispose of them properly. Replace mask filter elements according to the manufacturers recommendations. (Note: A workshop dust mask is NOT the same as a positive pressure Bio Mask). If there is ANY DOUBT WHATSOEVER in what you're dealing with, then contact a health professional before proceeding. Unless identified, treat all molds as a potentially serious health risk.
Many professional commercial tape cleaners employ a sapphire or ruby blade to break up the surface debris and burnish (scrape) the surface smooth & clean. Perhaps yet another bad analogy, but somewhat akin to a snowplow to remove the heavy "debris". The ruby or sapphire blades are effective on new tapes (ie: smooth paved roads if you will), but can totally trash an older tape with a binder just ready to delaminate. Like trying to plow snow from soft muddy driveway, the blade digs in and tears up surface. Thus the razor sharp scraper blade is the final blow and can peel the now aged softened binder right off the substrate. Never attempt to burnish a tape with any signs of mould if the binder is weak. The ruby/sapphire blade will scrape away the mould and sadly the binder as well. Then to add to the misery, mould spores can be thrown into the air where they can be inhaled. If not yet evident; removing mold requires specialized equipment and techniques. Before sending a vintage tape in for professional mold removal, make certain they have experience in handling such tapes.
In the case of just general cleaning where mold is not evident, most tapes we receive require but a single cleaning pass. Every so often, one will show up exhibiting severe mould growth, dust/grime, hexadecanoic acid deposits or any combination thereof. These are easy to spot, as they look like they might have just been fished out of a dumpster... (sadly, this isn't an exaggeration). Naturally, these tapes will require more than one cleaning pass, often using different specialized cleaning techniques, which is an additional charge.
Even tapes that aren't "gooey" from the effects of hydrolysis, can still stick and bind to the head drum simply from lack of adequate lubrication. The resulting stickiness here is quite different from that due to the effects of hydrolysis. The Binder Layer of virtually all magnetic audio and video tapes were impregnated with a lubricating agent when the tapes were manufactured. This lubricating agent serves to reduce friction and minimize wear. This lubrication is lost over time, partly due to the tapes' aging process, but also a small amount is "scraped off" each time the tape is played. Thus tapes that don't suffer from the effects of hydrolysis resulting in the dreaded "Sticky Tape Syndrome" or tapes that have been successfully baked, can still bind on the head drum simply from lack of adequate tape lubrication. Tapes that suffer the most from this effect are notably the older reel to reel tapes, though any tape older than 15 years is susceptible. Re-lubrication of the the tape involves a controlled reapplication of the lubricating agent to replace that which was lost, allowing the tape to glide smoothly over the head drum again.
In the case of weakened binders, the reduced friction reduces the effects of oxide shedding by the tape now "gliding" more freely over weakened areas.
We often get calls from folks whose tapes have been submerged in flood waters.
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Typical flood damaged tapes as received. |
In the case of flood damaged tapes, time is of the essence in getting them properly cleaned before irreparable damage ensues from possible contaminants in the water.
Although we have recovered flood damaged tapes up to 2 years after exposure, this was one of those exceptions where the "Video Gods" were in one of their more rare benevolent moods. Ideally, recovery procedures should be initiated as soon as possible after exposure - preferably within several days. The longer the tape is exposed to the inherent contaminants contained in the waters, the greater will be the risk of permanent damage.
Naturally, folks that have lost their homes have many more immediate pressing problems, so understandably, it's not unusual for us to receive tapes up to a month or more after exposure.
Though contrary to most people's natural instincts, tapes should not be allowed to air dry or left in the sun to dry, as the slow uneven drying often results in physical distortion of the tape, making playback unstable due to constant tracking errors, or in some cases, recovery impossible. The proper drying process is a critical step and must be done in a tightly controlled laboratory oven.
If the tapes have dried out, all may not be lost, but chances of a clean recovery are greatly diminished.
For tapes that are still wet or damp inside, the first on-site step you should take is to VERY GENTLY flush out what you can ..... Gently swirling them in a bucket of clean water is about the most "force" you want to use....
First of all, make certain the water you use to flush the tapes with, contains no chlorine, as is often found in most treated municipal water supplies. Rain water, well water or distilled water is free of chlorine & safe to use for general flushing out of the cassette shell. (The reason one must be certain the water is chlorine free, is that chlorine is an oxidizer that reacts with many organic materials as well as the metal particles in the binder.)
Before you begin, keep in mind the following:
DO NOT blast them with a hose, as the tape is especially fragile when wet. Don't attempt to remove it all, as without specialized equipment and cleaning techniques, you will be lucky to get even half of it, and attempting to do so risks damaging the very fragile tape... Remember; at this stage, you're only trying to dilute the heaviest of the contaminants including oils and solvents that were possibly in the flood waters. If on-site flushing is impractical as is often the case, don't panic.... it can be skipped if no other option exists.
Begin by submerging the tapes in a bucket of clean water (preferably distilled water if available) and keep them cool until they can be packed for shipment, making sure the shells completely fill with clean water. Doing so obviously keeps them from drying out, but also serves to further dilute whatever contaminants are still trapped inside. If worse comes to worse and no clean water is available, then dirty water will have to suffice until clean water becomes available - but make certain there is not the least hint of oils, solvents or chlorine ! In other words KEEP THEM WET - DO NOT LET THEM DRY ! - even if it means having to re-submerge them in murky water if there is absolutely NO other immediate option. Be sure to use enough water to completely submerge the tapes. Solvents, gas and oils if present, will float to the surface and you want the tapes below the floating layer of effluents. If in the northern latitudes, DO NOT permit them to freeze while still wet. As soon as possible, contact us for further more detailed instructions.
(Keeping them submerged and cool, slows any mold growth, further dilutes any contaminants and obviously keeps them from drying unevenly which can lead to tape distortion. Once allowed to improperly dry, the tapes may physically distort, and no amount of re-soaking will return them to their prior state)
Latent moisture makes for an excellent breeding ground for molds and mildew which require removal. Time is also of the essence here as well, as once the moulds grow into the binder, they sometimes become impossible to remove without destroying the tape in the process. Flood waters normally contain great quantities of organic materials and mould growth can be quite rapid - especially in warm tropical climates.
Flood waters also may contain, mud, silt, grime, both organic & in-organic materials, oils, gasoline, lubricants, solvents and a host of other contaminants which all must be removed. Mud and silt have an amazing propensity for finding their way even inside cassettes even stored in protective covers.
Removal of the tape from the cassette housing is required for proper cleaning and adequate air circulation when baked. Drilling drainage holes in the reel spindles is also sometimes required.
Some shells are thermally welded or the securing screws and internal components (springs, guide pins etc) have turned to "rust", necessitating having to re-shell the tape in a new housing. In most cases, the old shells are re-useable.
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Mud & silt even infiltrates the
cassette shells, which necessitates removal of the tape and literally
flushing out the heavy muck as the first step. Though it appears hopeless,
this tape and the 42 others in similar condition were recoverable. |
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These VHS-C tapes were likewise filled with mud. They're now washed & ready for the oven. After baking, they're put back in their shells and then run through the final cleaning stage. Finally they're placed in a vcr and "with fingers crossed", the transfer is made. |
It may seem like a penetrating glimpse of the obvious, but never store media in basements - especially in cardboard boxes that turn to "mush" when wet. Even on the off chance the flood waters were clean, the dissolved cardboard fibers make for a real mess and are loaded with contaminants all their own.
Due to the wide variations in types of damage, (gas, oils or solvents present in the water etc etc) it's impossible to predict the outcome of tape restoration efforts or even the costs for restoration. Some water damaged tapes need only a simple cleaning and baking, while most others require much more, such as removal of the tape from the cassette shells - especially if the waters were contaminated. There are so many variables, it's simply impossible to predict. Thus the best insurance beforehand, is to get them transferred and save copies in separate locations.
Successful recovery depends a lot on immediate attention as well as the type of water damage (ie: How many and what type of contaminants were in the flood waters). There are a lot of variables & unknowns and successful recovery is not always possible or guaranteed.
The process does not make the tapes immortal nor will it renew them to "Factory New !" condition. The positive effects of baking after submersion are normally short lived (lasting anywhere's from several days to a month or two). However, this allows a window of opportunity for playback to effect transfer to a new medium.
Though the master tapes are returned, we strongly recommend they never be played again. Note that we often remove & discard the internal spring locking mechanisms and sometimes other non-critical components that often have become rusted and prone to jamming. Note also that the adhesive paper labels rarely survive the cleaning process, so be sure to note any labeling before sending the tapes in.....
All of our efforts are spent cleaning and processing the all important tape. As such, we spend very little time in trying to make the old shells appear "as new". We clean those only to the point that affords reliable playback. In cases where there is too much internal damage to the shell & it's components, we will then re-shell the tape.
In the case of flood damaged recovery work, all of our efforts are targeted towards performing the recovery. As such, we do not perform any editing or spanning of tapes across DVD's...... Final labeling is by reel number, month/year when known and amount transferred.
Recovery Rates
1/2 inch, 3/4 & 1 inch tape formats usually have around a 95% success rate owing partly to their wider track pitch and lower data densities. These wider tape formats can sustain a fair amount of physical abuse, since any given area of oxide damage represents a much smaller picture area. Smaller format and metal particle tapes (8mm, Hi8 D8, MiniDV for example) generally have about a 70% chance of full recovery. The high data densities of these formats requires precise alignment and any damage represents a much larger image/data area. In other words, the smaller formats are not nearly as robust or "forgiving" as their older analog counterparts. Although mud and silts oozing out of the cassette shells may appear to make the situation hopeless, in fact, they do not pose much of a problem once properly removed. It's what you don't see that usually causes the serious permanent damage..... 70 to 95% recovery rates in light of all the tapes have been through is quite impressive (even we're still amazed after seeing their condition upon arrival ! ) These percentages however, can take a real "beating" the longer the delay before recovery procedures are initiated. I can't repeat it enough - - - TIME IS OF THE ESSENCE to afford the best chance of a full recovery !
Even so, we are in most cases still able to recover sections of Katrina damaged tapes being uncovered from below the rubble even a year later !
Any amounts of solvents in the water such as gasoline, oils, paint thinners, Acetone, Xylene, Xylol, fuel stabilizers, lacquers, etc etc etc can spell almost instant disaster - even in very small trace concentrations. However, even with heavy concentrations of solvents in the waters, some tapes will survive virtually unscathed, if they were lucky enough to fill quickly with "clean" water & sink rapidly to the bottom, where they are "protected" by remaining below the effluents floating and passing above. There are a lot of unknown variables !
To read more on video recovery, please refer to http://www.videointerchange.com/video_recovery.htm
Last Modified: Mar 1, 2008
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Video Interchange
92 George Luce Rd
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207-832-5064 - mail@videointerchange.com
Northeast Region - New England
