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Thread: 3M 996 Shed issue, revisited w/photo

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    3M 996 Shed issue, revisited w/photo

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    Several months ago, I had posted a thread about what appeared to be like sticky shed I was having with a box of 996 pancakes that I bought. I had noted that there was mostly white crud and long, thread-like strings. Not the usual brown gunk.

    Have been very busy and haven't had time to mess with it since then, until yesterday. Having thought about it for a long time, I thought I'd run a reel through the Revox again to see what happened. Used a reel that had already been through once. Cleaned heads, guides, etc. thoroughly before loading up the tape. Ran it through at 15 ips (to get it over with quickly), and stopped it three times, loosened the tape and checked the heads/guides, etc.

    The results: This time through, there was no squealing toward the end of the reel, and there was very, very little build up, if any, until the last 5 minutes of the reel. All the build up was white, filamentous, and there were a few of the thread-like strings that I got the first time that I ran this reel through. I took a photo of the erase head, which was the most affected. See the included photo, the arrows point out the threads and blob of white stuff.

    Unless I don't fully understand sticky shed, this doesn't look like sticky shed to me. Do any of you have any ideas what it could be? And, since there appears to have been improvement on the second pass through the machine, do you think it could be cleared up by somehow cleaning the tape?
    Attached Images Attached Images erase-head-close-up-copy-jpg 

  2. #2
    Beck Guest
    Sticky-shed will leave behind white or clear glue-like residue. Strings build up along edge-grooves on the head as they are filled in with residue.

    Refresh my memory. Was this new, sealed 996?

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    Quote Originally Posted by Beck
    Sticky-shed will leave behind white or clear glue-like residue. Strings build up along edge-grooves on the head as they are filled in with residue.
    You are describing exactly what I am getting. But, does sticky shed diminish with each pass through the machine like this appears to do?

    Refresh my memory. Was this new, sealed 996?
    Yes, it was a whole box of pancakes, each still in plastic, each still sealed with the 3M adhesive leader on it, never used. The box in question is from pretty early in the production run of 996.

    FWIW, it appears that 3M did not actually "seal" pancakes in the plastic bags. Every box of 996 pancakes I've ever gotten has the pancakes in the same type of plastic bags, but the bags are always folded over the same way and kind of tucked in on the pancake trays, but they are not heat sealed shut.

    I thought that 996 never suffered from sticky shed.

    Maybe, if 996 doesn't normally get sticky shed, then what I'm getting is some mild variant of it. There is no oxide shedding going on, just the white stuff. If this is a milder relative of sticky shed, or something that looks like sticky shed but is not as bad, then do you think baking it might fix it permanently? Or very long term?

  4. #4
    Beck Guest
    See if it comes off with a dry Q-tip... if it does it's not sticky-shed. According to 3M, 996 and 986 (966) are not prone to sticky shed per se. However, these tapes could be showing signs of some other breakdown Ė maybe just a bad batch. I would expect some light oxide shed, but that should be brown.

    3M started using a different binder when 996 and 966 were introduced (so they said). 1991 was before sticky-shed was discovered though, so they didnít change the binder because of it.

    Another idea Iíve seen kicked around in years past is that different brands of tape have slightly different widths. Manufacturers donít have the same slitting machines to cut the tape. Some 3M tapes, such as 226, were a bit wider than Ampex. Thus, if you have an older machine with a tape path worn by 456, a slightly wider tape will experience edge damage. This could manifest itself with strings of residue, in addition to the normal powdery oxide. Maybe the 1991 batch is a hair widerÖ or maybe not. Iím not experientially familiar with this, but Steve Albini wrote an article about it 10 years ago or so.

    Something to try besides baking, though time consuming, is an alcohol bath. Archivists at the Library of Congress do this for contaminated tape (not sticky-shed).

    Use 90% Isopropyl alcohol or better. Run your machine at play speed while holding a lint-free cloth dampened with alcohol against the tape, between the first tape guide and the head assembly. A second piece of cloth should be stretched across the heads to dry the tape and protect the heads. You can cut pieces from an old T-shirt for the cloth. I would fold the cloth that covers the heads so itís four layers thick.

    After the tape has run through, take the full reel and put it back on the supply side. Next, play it through again with the fan blowing on it to facilitate evaporation of any remaining alcohol.

    This sort of heroic procedure is normally reserved for recovery of valuable recorded material, but if you really want to keep that tape and have the time itís worth a try.

    Me, unless I had some material I was trying to recover I would cut my losses and start using Quantegy GP9Ö well actually, on an A77 I would be inclined to use 456 or RMGI 911, but thatís beside the point.

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    3M made some really, really dirty running tape. Like, little piles of oxide underneath the the contact points of the tape path dirty. I had a reel of 250 that I had to run through 7 or 8 times to get all the crud off; after that it was fine.

    I've got some tape from the same family as 996, and it's doing just what you describe: crud buildup extraordinaire on the first three passes, less on the fourth, and runs fine thereafter. I strongly suspect that this is *not* SSS, but I'll be really annoyed if it is.

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    Quote Originally Posted by Judas Jetski View Post
    3M made some really, really dirty running tape. Like, little piles of oxide underneath the the contact points of the tape path dirty. I had a reel of 250 that I had to run through 7 or 8 times to get all the crud off; after that it was fine.

    I've got some tape from the same family as 996, and it's doing just what you describe: crud buildup extraordinaire on the first three passes, less on the fourth, and runs fine thereafter. I strongly suspect that this is *not* SSS, but I'll be really annoyed if it is.
    Since they last talked about this in 2006, the tape has probably became even stickier.

    Alan.

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    It gets better when aged.


    I have a bunch of 996 2" reels (most were gotten used), and upon running each reel a couple of times through just to clean off the dust and any loose grime that might have settled on them during the years, since some of the reels are at least 15-20 years old...I didn't notice any SSS issues with them, just a little loose oxide on the first pass or two, and then they all cleaned up nice. They actually ran smoother/cleaner than a lot of the Ampex/Quantegy 499 reels I have.

    I'm currently recording with the 499....but I'm saving the 996 for some point in the future when I decide to recalibrate specifically for it, and I don't expect it to be a problem.

  8. #8
    Beck Guest
    Yep, what miroslav said.

    Judas, I'm curious about what model tape from "the 996 family" you're referring to. The older stuff, 206/207 runs the cleanest and is IMO still one of the best tapes around. 226 will have sticky-shed and 250 will most likely have it. 966 (later 986), which was made to replace the sticky-shed 226 is also good stuff. It's basically 226 with a new binder formula, but they changed the model number because of the bad rep 226 had for going sticky very quickly... a lot sooner than Ampex of the same era.

    Quantegy GP9 is an improved 3M 996. After Quantegy acquired 3M magnetics they worked to create a cleaner running 996, and that's what GP9 (Grand Platinum +9) is.

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