Treating sticky VHS tape with airtight bag, desiccant?

[vhsnewb]

After a long pause, I’m restarting my VHS capture project, and I need to figure out what to do about several “sticky” tapes I know I have (and likely many more that I haven’t identified yet).

I posted about this before, specifically about tape baking: https://www.digitalfaq.com/forum/vid...pe-baking.html. I'd also like to explore a possibly gentler option of putting the tapes in an airtight bag with desiccant packs.

To recap, I have some tapes that sound a lot like this:

Quote:

Dealing with 'sticky-shed tape syndrome' has been one of our ongoing concerns. We receive weekly calls from VCR owners with clogged video decks caused by sticky tapes. When tapes have been stored for many years in an environment with humidity above 45%, the binder on the tape releases, causing 'sticky-shed syndrome'. This causes tapes to stick to the VCR's transport path. VCRs suddenly slow down during playback, video heads clog, and the whole tape path gets gummed up.

I have tapes with those symptoms, as well as one tape that will literally stop playback like the machine hit the end of the tape. I also have some that seem to have a minimal amount of stickiness, where I’ve been able to capture them but the VCR sounded like it was struggling in places. I've also had a couple of my VCRs get extremely gunked up, which I assume is due playing tapes like those.

I read a mention of an attempt to cure a sticky tape with desiccant in this 2013 account of the restoration of only extant copy of Game 5 of the 1973 NBA finals from a non-VHS Cartrivision tape:

Quote:

To rid the tapes of the sticky-shed syndrome, Schechter first tried to absorb the moisture by sealing the tapes in an airtight bag with desiccant, such as silica gel, for a month. That didn’t work. Then he scrubbed the tapes clean with a tape cleaning machine. The tapes were still sticky. Then he incubated, or baked, the tapes at a low temperature in a specialized oven. Still, the stickiness remained.
….
Then, at 2:00 a.m. on that Saturday morning, he raised the temperature of the incubator to just below that at which plastic melts. If Schechter was wrong, it would destroy the tapes. “I knew it was a one-way trip,” he said. “But it was either that or nothing. I was basically out of options.”
When he removed the tape 24 hours later, the plastic reels had begun to melt, but the tape stayed intact. He described the feeling as pure euphoria when both cassettes actually played from beginning to end without getting stuck and he was able to record the video digitally.

The person who was doing this "heads up the restoration division of New York postproduction house DuArt Film and Video," and had "been working with videotape for 37 years."

Has anyone heard of the technique of "sealing the tapes in an airtight bag with desiccant" or had any success with it? Ultimately he had to do an aggressive bake, but he was dealing with a worst-case tape. I’m wondering if it might be a good option to use this technique as a “standard procedure” before capturing a tape, to minimize the possibility of stickiness without the aggression and risk of baking. I have some good-quality mylar bags and fresh silica desiccant packs (I know can get the RH down to ~0% in those bags). Are there any problems with this idea that would make it unwise?

-- merged --

I was doing a little more research on this, and found this mailing list post:

https://cool.culturalheritage.org/by.../msg00340.html:

Quote:

Date: Wed, 14 Feb 2007 14:03:50 -0500

....

Polyester-base audio tape, all video tape and optical discs can benefit from
being stored with desiccant if the temporary storage environment is likely
to experience high humidity. These materials include moisture only as a
"contaminant" and do very well in extremely low humidity.

Acetate-base audio tape and film should NOT, as a general rule, be sealed
with a desiccant as some moisture is necessary for their "well being".

....

Peter Brothers
SPECS BROS., LLC
973-777-5055
peter@xxxxxxxxxxxxx

Tape restoration and disaster recovery since 1983

I understand Lord Smurf recommends SPECS BROS for tape restoration and cleaning, so I take it that opinion is trustworthy and storing VHS tapes (as a subset of "all video tape") would at least do no harm.

[timtape]

Quote:

Originally Posted by vhsnewb

I was doing a little more research on this, and found this mailing list post:

https://cool.culturalheritage.org/by.../msg00340.html:
I understand Lord Smurf recommends SPECS BROS for tape restoration and cleaning, so I take it that opinion is trustworthy and storing VHS tapes (as a subset of "all video tape") would at least do no harm.

I think it's important to note Peter Brothers' qualification. He wrote: "... all video tape and optical discs can benefit from being stored with desiccant if the temporary storage environment is likely to experience high humidity . " (My emphasis).
He's not saying this should be done routinely but in the expectation of temporary high humidity.

High humidity is a perfect environment for mould, which is a good reason to avoid such a storage environment. Mould can often be removed in preparation for playing the tape but it's not an easy task to remove it properly so better of course to reduce the risk of mould formation in the first place.

[vhsnewb]

Quote:

Originally Posted by timtape

I think it's important to note Peter Brothers' qualification. He wrote: "... all video tape and optical discs can benefit from being stored with desiccant if the temporary storage environment is likely to experience high humidity . " (My emphasis).
He's not saying this should be done routinely but in the expectation of temporary high humidity.

I think some extra context from the thread I quoted is important: Peter Brothers was answering a specific question from a woman who had to move her archive (of quite varied media) to a temporary storage location for an indeterminate period of 5 or 6 months or more. I think "temporary storage environment" was specifically referring to that woman's situation. I think the more generally relevant statement was "Polyester-base audio tape, all video tape and optical discs.... These materials include moisture only as a 'contaminant' and do very well in extremely low humidity."

But in any case, my question isn't about mold or long term storage, but about treating and preventing playback problems due to sticky tapes. If Peter Brothers thinks it's fine to store a videotape in a bag with desiccant for 6+ months, then I'd imagine he wouldn't think a tape would be damaged by doing a similar thing for only one month to treat a sticky tape (barring some sticky tape-specific complication).

Which brings me back to my original question: does this technique actually work for some sticky tapes? Is it worth trying? Is it worth doing as a preventative measure (e.g. before attempting to capture, put the tapes in a bag with desiccant for a month, then play them)?

[lordsmurf]

Physically damaged media has too many variables, and inexperienced users are rarely able to properly ascertain the methods needed to properly recover the media. So for that reason, I generally prefer to not comment in threads like this. In fact, I generally heavily dissuade users from potentially (LIKELY!) ruining them further.

I'm really not sure if a desiccant will help or harm here, or even do nothing. If you don't actually care about recovering the content, and this is merely an academic exercise, then run a full spectrum experiment. No desiccant in a bag with a tape, one "serving" in another, more in others. The "serving" size will probably be guessed.

You might even ask Spec Bros, but I'm pretty sure they'll just dissuade DIY, and strongly suggest you let them handle it.

Understand this is not typical, still less than 1% of tapes have such issues. It's far more than it used to be, but still 1%. In another decade, probably more. This is the sort of problem that will hit us in a wave, not a trickle, as we approach magnetic media EOL. VHS is 35-65 years, and we're at about year 45 for 70s tapes, years 35-40 for early 80s tapes. By 2040, I'm confident that things will quickly turn ugly. (But by then, I'll hopefully be retired, doubt I'll care too much.)

[timtape]

Quote:

Originally Posted by vhsnewb

...Which brings me back to my original question: does this technique actually work for some sticky tapes? Is it worth trying? Is it worth doing as a preventative measure (e.g. before attempting to capture, put the tapes in a bag with desiccant for a month, then play them)?

I guess the best way to know from personal experience is to try it. It seems like it wont do any harm.

It seems VHS and Betamax tapes rarely exhibit binder problems such as stickiness. I've found it hard to find a list of VHS or Beta tape brands and types which regularly require baking, whereas it's not hard to find a list for classic open reel audio tapes such as Ampex 40-, 45- etc. On his website Peter Brothers identifies some Betacam and Umatic tapes requiring treatment but I dont recall him mentioning any VHS or SVHS tapes. That doesnt of course mean there arent any.

Do your sticky VHS tapes share anything in common such as same brand, type, same storage conditions compared to the others which didnt etc? Any evidence of mould on the top of the tape packs? Is it possible these few tapes share some other problem such as sticking because of a faulty cassette including faulty parts inside the cassette?

Here is Peter Brothers' website address. Lots of useful information: http://www.specsbros.com/

[latreche34]

By the time of VHS era, magnetic tape manufacturers have almost perfected the bonding agents that adhere the magnetic particles to the plastic film, Any magnetic tape no matter how good is can have problems with poor storage conditions, Extreme heat and cold alternation as well as moisture can pretty much destroy anything. Ampex is a well known company that had/has higher failure in SSS (sticky shed syndrome), Starting from their early reel to reel audio and video tapes, to pretty much anything else, DAT, DDS data, VHS, Beta you name it.

There is a member at tapeheads.net use to work for BASF and he is one of the most knowledgeable people I've ever interacted with in terms of tape chemistry, I believe his member name is steerpike, Feel free to join and ask.

[aramkolt]

Not sure if this has ever been tried, but what about running the tapes cold - say entire VCR in a refrigerator and tapes stored in refrigerator beforehand. Typically gummy adhesives are less gummy at colder temperatures. Guessing operating temp of a VCR can handle fridge temps as long as your air isn't humid beforehand which could cause condensation on VCR parts that you wouldn't want. Maybe give that a go with a cheap VCR and a tape that you haven't been able to fix by other means. You'd probably want the top cover of the VCR off as well so that any heat generated by the power supply and other components escapes upwards without heating up the deck area.

That suggestion is really only good if your goal is to get a digital backup of the tape, don't think it's going to help you long term to reverse any damage already done or make it any less likely to progress.

If you try it, let us know how it goes!

[timtape]

"cold play" has been used with some success on (again) open reel audio tapes. See Richard Hess Degrading tapes. https://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-audio/degrading-tapes/
Hess mentions VHS in passing in relation to the audio tracks but makes no mention of sticking or squealing, which is strange if there are documented problems inherent in the VHS tapes.

For me the problem is finding anyone who can report stickiness in a VHS tape which is inherent to the tape, not due to external factors such as flooding, mould, contamination with sticky material etc. Has anybody here experienced such VHS tapes? Even one?
The people who should know about such cases would normally be the bigger media transfer companies or archives where a large number and variety of VHS tapes have passed through their hands over the years.

[aramkolt]

Personally haven't experienced one, but why not give it a try? Sounds like there's a good chance it will show some improvement.

I don't know that most professional transfer services would bother dealing with difficult tapes, or just run them as is and the result just is what it is. Or at least that's what some online reviews would suggest.

[timtape]

Quote:

Originally Posted by aramkolt

Personally haven't experienced one, but why not give it a try? Sounds like there's a good chance it will show some improvement.

I wasnt being merely rhetorical. I for one have already invited anyone who has such a tape, to name the tape brand and type, upload a few photos, and we try in good logical fashion to eliminate every other possible cause so that it must be something in the tape manufacture itself. Then see if other samples of that tape brand and type are showing the same symptoms. If vhsnewb really has such a tape(s) it's highly likely there will be many more such tapes out there. But vhsnewb hasnt posted for some days now. Hasnt responded to questions. Not sure why.

Quote:

Originally Posted by aramkolt

I don't know that most professional transfer services would bother dealing with difficult tapes, or just run them as is and the result just is what it is. Or at least that's what some online reviews would suggest.

It's hard to know what can be going on. I suspect it varies greatly between different companies and individuals. But it doesnt take much intelligence to make a note of particular brands and type of VHS tapes with problems, especially companies which dont want to deal with such difficult tapes.

[vhsnewb]

Quote:

Originally Posted by timtape

Do your sticky VHS tapes share anything in common such as same brand, type, same storage conditions compared to the others which didnt etc? Any evidence of mould on the top of the tape packs? Is it possible these few tapes share some other problem such as sticking because of a faulty cassette including faulty parts inside the cassette?

I have pretty incomplete info. I have not attempted to capture all of the tapes I plan to. I also don't think the tape labels are totally reliable to determine brand. Many are unlabeled, labeled with generic labels, or (probably) a label from a different brand of tape. I'm also going off my notes and recollections from a year or two ago.

All the tapes were stored in roughly the same conditions for the last couple decades. Some of the ones I've had the most trouble with are from the 80s, so I've avoided attempting to capture similar tapes and have been saving them for the end of my project. IIRC, some of those tapes may have spent an extra decade in a midwestern basement, which is not noticeably damp or humid. None of them have been submerged, stored in non-climate-controlled conditions, etc.

Attached are some images of the "sticky" tape I've spent the most time with. I was also the first one I encountered, and after this one, if something stopped playing in the middle or struggled too much, I would just stop the capture and move on. When I started with it, it was advanced towards the end, and I couldn't rewind past a certain point with a VCR. I managed to rewind all the way to the beginning with a rewinder and did a partial capture of the beginning, but stopped after I hit the sticky area from the other direction. I have a note "friction & squeaking/stopping 1.5 hrs in."

My assumption is that I've been dealing with sticky tapes is because of the "friction & squeaking/stopping" symptom, and two VCRs that got very dirty (the one I personally opened up and tried to clean looked kind of like this photo). The guides on this tape also have a similar buildup.

Quote:

Originally Posted by timtape

But vhsnewb hasnt posted for some days now. Hasnt responded to questions. Not sure why.

This is a hobby side-project of mine. I can't work on it every day, since I have other things going on.

[timtape]

Thanks for the extra comments and images.

It's not necessarily easy or inexpensive to do but with problem tapes I'm convinced of the value of cleaning them before transfer. Here's Specs Bros on tape cleaning. Worth reading in full.

http://www.specsbros.com/white-paper...-cleaning.html

With one of your valued oldest obviously dirty tapes why not send it to Specs Bros or someone similarly skilled and equipped, for examination and a thorough clean. Specs Bros have many specialised cleaning machines. Then try playing it in a good VCR known to be in excellent condition (including its ability to wind the tape as new) and obviously with its full tape path (not just the video heads) also very clean, not just with a cleaning tape but a full manual clean.

If you arent able to do this work yourself (understandably most cant) I guess someone else with the skills and tools would need to do it. Obviously no amount of dessicant in a bag or cold play is a substitute for first removing deposits from the tape, the cassette and its fixed guides, and the VCR's tape path. Failure to properly clean the tape and cassette, sometimes before even attempting to play or wind it, and failure to use a good, well maintained VCR , always with clean tape path, seems common. Sometimes the solution is neither easy nor cheap.

[vhsnewb]

Some updates:

I had a very interesting and informative email discussion with a VHS preservation expert a last year, but I don't think I should direct quote in a public forum because it was a private communication. Here's a quick summary of what I learned (all my wording, so I probably got some finer points wrong, at least):

• Polyester-base tapes (like VHS) should be able to be stored indefinitely in a low humidity environment. Humidity is a chemical contaminant in them.
• It's not been extensively studied what low humidity does to the glues used in tape splices.
• Video tapes including VHS do suffer from binder hydrolysis, even later professional Beta format ones. It's just not as bad as older reel-to-reel tape.
• Binder hydrolysis breaks the polymers into shorter oligomers. The reaction is bi-directional, and can be reversed to re-form the oligomers into polymers (but not exactly the same, they're shorter). Shorter polymers are more subject to binder hydrolysis.
• Exposing a hydrolyzed tape to a low humidity environment (20% to 30% or lower) for (as a rule of thumb) 3 to 6 months can cause the oligomers to re-form polymers.
• Tape baking for less than a day causes the oligomer residue on the surface to be reabsorbed into the tape. It takes 3 days of baking before there's noticeable crosslinking of the oligomers into polymers.

I did an experiment to see what kind of humidity I could achieve with the mylar bags (AwePackage half-gallon 8x12") and silica desiccant packs (Dry & Dry 20 Gram, Blue Indicating) I mentioned above. I packed two half-gallon bags with two tapes per bag, a Ambient Weather WH31E sensor, and varying amounts of desiccant. The sensors have a range of 10 to 99% RH with an accuracy of ±5% (only guaranteed between 20 to 90%), and I calibrated them (on the base station) with Boveda 32% calibration kit. I also had a sensor in the room to record the ambient indoor humidity outside the bags. I arbitrarily let the experiment run for 9 months, because I moved on to other things for awhile.

These were just random commercial tapes, not sticky ones, so I can't say anything about the effects of doing this to fix a tape.

My results: the one-packet bag got down at low as ~20% RH, and the two-packet bag got to ~10%. It takes a month or more to reach the lowest RH value.

I'm a little skeptical of the 10% value, because I was told commercially available desiccants usually can't achieve less than 20% RH and I'm using consumer-grade sensors at the limits of their range).

Below are the graphs of my data, as well as attached images showing how I stored the tapes in the bags (they were stored so the tapes would be on-edge, with the zip closure unstressed and hanging over the edge of a shelf).

The beginning if the graphs requires some explanation: I kept the sensors for a little while in a bag with a 32% Boveda two-way humidity control packet. Then I got everything setup but let the bags sit open for a couple days, then sealed them. I initially didn't fully-seal the one-packet test. So after noticing the problem I opened up the bag, replaced the packet with a fresh one, and sealed it properly.

2024-06-26 one-packet test graph.jpg

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[lordsmurf]

I read your post, interesting.

Some comments:

Quote:

Originally Posted by vhsnewb

I had a very interesting and informative email discussion with a VHS preservation expert a last year,

This is a situation of "name or BS" (sort of like "pics or it didn't happen"). A lot of so-called "experts" are just morons in their garage or basement. To be vetted as an expert, I need to know vastly more. Not necessarily even their "real name", just a name to vet them.

Because:

Quote:

Polyester-base tapes (like VHS) should be able to be stored indefinitely in a low humidity environment

No.

After about 65 years, all bets are off. The range is 35-65 years for the chemistry, and of course you get exceptions above and below that. But after 65 years, expect the worst at any time. I deeply studied this in the late 2000s, even digging through patent documents. I was tired of reading BS about "tapes die in 10-20 years" -- which was marketing BS from hack conversion services (and a misquote of false optical longevity information released by IBM employees, which is where the 5-10 / 10-20 claims originated in the early 2000s; the irony here being that IBM sold magnetic media, and it was an anti-optical campaign, so it's amusing the it went full circle to again falsely be claimed against a consumer magnetic media format!)

^ This is a benefit of "being there", most users don't remember this, and the origins were somewhat scrubbed offline over the years.

Quote:

Humidity is a chemical contaminant in them.

Huh? Jabberwocky. Misquote?

Quote:

It's not been extensively studied what low humidity does to the glues used in tape splices.

No. Well, yes and no. Most/all adhesives (used for splicing, whatever) = well studied. The tapes = well studied. So the "adhesives used on tape" is really somewhat moot/immaterial.

Quote:

Video tapes including VHS do suffer from binder hydrolysis, even later professional Beta format ones. It's just not as bad as older reel-to-reel tape.

Yes, but also no. Wide variation in formulations. For example, some 90s tapes were crap when produced, fell apart at the moment of usage in a deck.

Quote:

Binder hydrolysis breaks the polymers into shorter oligomers. The reaction is bi-directional, and can be reversed to re-form the oligomers into polymers (but not exactly the same, they're shorter). Shorter polymers are more subject to binder hydrolysis.
Exposing a hydrolyzed tape to a low humidity environment (20% to 30% or lower) for (as a rule of thumb) 3 to 6 months can cause the oligomers to re-form polymers.

Stuff like this always amuses me. Referring to this "expert", and to quote (paraphrase) a Pickles comic: "If you can't put it in plain English, then you don't understand it yourself".

Quote:

It takes 3 days of baking before there's noticeable

No. Varies based on factors.

Quote:

I did an experiment
I'm a little skeptical

This is also amusing, because it's eerily familiar to the ramblings of (and trolling of) the banned member gamemaniaco (and multiple aliases) all throughout the 2010s on this site and multiple others.

As I told him, way too many times, bags trap moisture and/or induce moisture. So sealing something in plastic has the opposite effect as intended, and the included desiccant serves no real purpose other than to remove the created moisture/humidity. True, it may reverse some of the RH% of your natural environment, but it will not be excessive.

So part of this experiment actually says more about your location than it does the methodology of the experiment itself.

I realize this may come across wrong/whatever to some, but you must understand I've interacted with a lot of "experts" over the years -- people that don't know their ass from their elbow. I question a lot of what I read here in your post. As a newbie, you can be "ooh'd and ahh'd" by smooth talked BS. I see the BS, or at least "off" information. Now, to give benefit of the doubt, perhaps it is misquote, or perhaps it was simplified info to introduce you to the topic. Hard to say. That's when knowing the source matters, either "oh yeah, him/her, good info there (but you probably misread/misheard)" or "who the f* is that?"

My only advice here is "proceed with caution".

A random Redditor gave a good concise quote:
"The tape used is coated with liquid oxide and then charged magnetically. Those particles are going to degrade over time and no longer be magnetic. The "degradation" of vhs is speaking on the slurry used to coat the tape. The binder will also become brittle and cause wraps in the tape. It is not a myth at all. There is no "end" of a tapes life. It will not just one day "break" suddenly. It is going to slowly fail over time. Like a car battery holding a charge. Even if you do not use it, the charge will not last forever."

^ This is essentially correct, in laymen's terms. No jabberwocky required to understand it.

No amount dehumidifying and/or plastic bags/baggies will change this fact.

As I often write, VHS tapes are essentially rusty goo on Mylar/plastic. It will break down like any other rust, goo, or Mylar/plastic. That Mylar/plastic is also made of oil -- meaning from dead dinosaurs.

Even stone tablets don't last forever.

[vhsnewb]

Quote:

Originally Posted by lordsmurf

This is a situation of "name or BS" (sort of like "pics or it didn't happen"). A lot of so-called "experts" are just morons in their garage or basement. To be vetted as an expert, I need to know vastly more. Not necessarily even their "real name", just a name to vet them.

Maybe so, but not the person I was communicating with. He is an actual respected professional, someone I think you're familiar with. I'm just not going to direct-quote or name names from any private communication out of courtesy.

Quote:

Originally Posted by lordsmurf

Quote:

No.

After about 65 years, all bets are off.

I can see how that statement was confusing. The context is the discussion upthread about if a low humidity storage environment will damage tapes over the long term, and the answer was no. I don't think anyone is claiming tapes in such an environment will last forever.

Quote:

Originally Posted by lordsmurf

Quote:

Huh? Jabberwocky. Misquote?

No it's not. The email list post from Peter Brothers quoted upthread says exactly the same thing. Some materials require a little water as part of their structure, and I understand he's saying VHS tape is not one of those materials and the water is just a cause of problems with it.

Quote:

Originally Posted by lordsmurf

Quote:

No. Well, yes and no. Most/all adhesives (used for splicing, whatever) = well studied. The tapes = well studied. So the "adhesives used on tape" is really somewhat moot/immaterial.

I understood that to be a caveat, qualifying that extended exposure to low-humidity is known to be fine for the magnetic tape itself, it's not been studied what such extended exposure would do to the glues used in the splices. It could be helpful or harmful.

Quote:

Originally Posted by lordsmurf

Quote:

Stuff like this always amuses me. Referring to this "expert", and to quote (paraphrase) a Pickles comic: "If you can't put it in plain English, then you don't understand it yourself".

It's chemistry, so plain English doesn't really apply. It's been a while since I've been in a chemistry classroom, but it made enough sense to me. Basically you have a reaction where water molecules come from the environment and insert themselves into polymers, breaking them into smaller pieces. If you take enough water out of the environment, you can affect the equilibrium of the reaction so that water molecules (on average) pop back out and longer polymers form from shorter ones.

Honestly, this is the bit that's the most compelling to me: a plausible chemical mechanism.

Quote:

Originally Posted by lordsmurf

This is also amusing, because it's eerily familiar to the ramblings of (and trolling of) the banned member gamemaniaco (and multiple aliases) all throughout the 2010s on this site and multiple others.

I'm going to ignore that comparison.

Quote:

Originally Posted by lordsmurf

As I told him, way too many times, bags trap moisture and/or induce moisture. So sealing something in plastic has the opposite effect as intended, and the included desiccant serves no real purpose other than to remove the created moisture/humidity. True, it may reverse some of the RH% of your natural environment, but it will not be excessive.

Trap moisture, yes, but by what mechanism is moisture "induce[d]" or "created"? It's got to some from somewhere. The condensation reaction I mentioned above?

The only purpose the bags serve here is to prevent the little 20g silica packets from turning into really poor room dehumidifiers.

Quote:

Originally Posted by lordsmurf

the included desiccant...it may reverse some of the RH% of your natural environment, but it will not be excessive.

Which is more-or-less what I was trying to empirically find out in my experiment: get a rough feel of how effective these packets are in these bags with VHS tapes.

Quote:

Originally Posted by lordsmurf

No amount dehumidifying and/or plastic bags/baggies will change this fact.

I don't think you understand my goals. I'm not trying to preserve these tapes forever. I don't even plan on keeping them after I'm done capturing them.

Anyway, what I'm sharing here is what I've learned and my attempts to checking my assumptions with the tools I have on hand, in the off chance that someone else may find it helpful.

[timtape]

vhsnewb, the person I suspect you have been communicating with is indeed very knowledgeable and experienced and well respected in the industry for decades. He occasionally contributes to another forum of which I am a member. When he offers advice, wise people sit up and listen attentively...

[lordsmurf]

Quote:

Originally Posted by timtape

vhsnewb, the person I suspect you have been communicating with is indeed very knowledgeable and experienced and well respected in the industry for decades. He occasionally contributes to another forum of which I am a member. When he offers advice, wise people sit up and listen attentively...

Hopefully so!

It's just that, without any reference, it's "some random guy told me this", which we have far too much of in our current Youtuber "expert" society. So when conversations start to veer that direction, I feel the need to interject for the good of all readers.

Quote:

Originally Posted by vhsnewb

I can see how that statement was confusing. The context

Ah, gotcha, that mattered.

Quote:

Some materials require a little water as part of their structure, and I understand he's saying VHS tape is not one of those materials and the water is just a cause of problems with it.

The word "contaminant" is what I took/take issue with. The structure of tape will contain some % of water, like almost everything else. I don't necessarily agree it's contamination as much as simply being part of the structural makeup. I know science can waffle on that definition, between latter adds/changes vs. intrinsic impurities. Good explanations.

Perhaps we're just disagreeing on syntax here, and I dislike semantic arguments, so I withdraw my comments.

Quote:

it's not been studied what such extended exposure would do to the glues used in the splices. It could be helpful or harmful.

I don't see any way that it could be deemed helpful. It's really a case of "how harmful", but that depends on so many factors that it's hard to create such an exacting experiment, especially with a format that (essentially) no longer exists. And extant tapes are so far from factory now that age itself introduces variables.

Quote:

It's chemistry, so plain English doesn't really apply.

Yep.

Quote:

Trap moisture, yes, but by what mechanism is moisture "induce[d]" or "created"? It's got to some from somewhere. The condensation reaction I mentioned above?

Correct, condensation. And any present H and O elements can also be induced to form H2O.

Quote:

Which is more-or-less what I was trying to empirically find out in my experiment: get a rough feel of how effective these packets are in these bags with VHS tapes.

I would suggest at least 90% of the silica is merely fending off the bag-induced humid/moist environment, and maybe 5% goes towards the external environment.

Here's an idea for another experiment you can run:
If you want to test for a term (weeks to start, then months), I'd suggest seeing how a tape-sealed double corrugated box with silica compares. Obviously cardboard is ephemera longer term (years), but it does absorb moisture, as well as re-expel it when the external environment RH% changes back lower. That would remove the plastic bag as a variable.

I ran excessive CD/DVD experiments in the 00s. I actually found that my carpet-lined car trunk held up best, even if the temps were as much as 160-F internally at times. Discs in an outdoor building, or attic, or garage, were vastly worse off. The main differing factor was carpet lining. I wish I'd have run more test on cardboard back then.

Quote:

I don't think you understand my goals. I'm not trying to preserve these tapes forever. I don't even plan on keeping them after I'm done capturing them.
Anyway, what I'm sharing here is what I've learned and my attempts to checking my assumptions with the tools I have on hand, in the off chance that someone else may find it helpful.

Don't get me wrong either. It's interesting discussion, regardless of findings. I'm just not all that trusting of anonymous 3rd party claims, as well I should be. As we all should be, in our age of disinformation and misinformation.

[aramkolt]

Not sure if anyone has tried this, but if you really want to get all of the moisture out of the tape, you could put it under high vacuum and that would get it drier than any of the other methods discussed. It may also cause any volatile compounds to gas off as well which I am unsure if that would be a positive or a negative when it comes to tape restoration.

Typically, this would be done with a freeze drier, but since there isn't a significant amount of water in the item, there's no need to actually freeze the tape first and you'd just need a vacuum pump and a vacuum chamber both of which could be had for less than $200 and probably an hour at most in the chamber. A traditional freeze drier has a "cold trap" to sequester water vapor which will damage a vacuum pump, but that wouldn't really be needed here due to the relatively low moisture content.

Before actually trying that, you'd want to do it on a normal tape to prove that this doesn't damage normal tapes of course, and maybe try your other method first, then see if you get a better result after.

I did see this article, but this is more in reference to tapes that were submerged in water rather than sticky shed:
https://resources.culturalheritage.o...ed-videotapes/

My hypothesis is that a freeze dried tape would actually shed (a lot) more *if* it disrupts the adhesive, but not be sticky at all after the drying.

[lordsmurf]

Since moisture is an intrinsic aspect to tape, complete removal would inevitably result in problems.

You must understand that tape is fickle. If it's too cold, it ruins. If too hot, it ruins. If too dry, it ruins. Videotape has a goldilocks zone, like anything else. Extremes are bad. Even semi-extremes can have negative outcomes.

Aged oxide loves to strip/shed these days.

[vhsnewb]

Quote:

Originally Posted by vhsnewb

Some updates:
I initially didn't fully-seal the one-packet test. So after noticing the problem I opened up the bag, replaced the packet with a fresh one, and sealed it properly.

I just noticed that the annotations I added to the graph were missing from the version I uploaded. I can't seem to edit the post anymore, so here's a corrected version:

2024-06-26 one-packet test graph-corrected.jpg

Quote:

Originally Posted by lordsmurf

I would suggest at least 90% of the silica is merely fending off the bag-induced humid/moist environment, and maybe 5% goes towards the external environment.

Personally, I think there's kind of two phases: 1) the desiccant and the bag contents (including trapped air) reach equilibrium at some RH%, and 2) leaks in the bag allow humidity from the environment slowly infiltrate and saturate the desiccant, causing the RH in the bag to rise.

I'd previously done an (accidently very long term) experiment with just the two sensors in a single bag with one 20g silica packet (and most of the air pushed out). The rate of increase in RH% slowed noticeably during the winter months, when the external RH% was low, then picked up again in the spring/summer/early fall, when the external RH% was high.

I'd share graphs, but I had a lot more corruption in those files and I'd have to do more work than I want to do to piece it together to be presentable.

[As an aside, the graphs I've shared show a relatively warm and therefore humid winter. They're usually much drier, like 20-30% RH.]