Odd tape dilemma...

[Teeg]

  I purchased a collection of studio tapes, all 7.5 ips 1/4" 10.5 NAB reels, that contain various music titles; each reel arranged by genre. Best guess is that the tapes were originally masters for radio stations to build playlists from. Problem is that the tapes are wound upside down on the reel (the oxide is out). The boxes are marked 'tails out', and at first glance that seemed correct, but the tape is definitely wound incorrectly.
  I cant figure out how one would do that in the first place, let alone fix it. All of the tapes (around 200) are like this. Has anyone run across this before, or know how to un-do the incorrect wind?

Regards,
Tj

[docb]

A Nagra T can handle tape wound either way by setting a switch. There may be some other machines that can do this as well. It would be a matter of finding one that can and using it to rewind the tapes off the "original reels and onto a reel with the oxide in, then playing them off that reel onto the original reel with the oxide in and the tail out.

[ironbut]

Hi Tj,

What you've got there are tapes in what's called B wind. That's with the oxide out as you already know. What you may not know is that all cassette cased tapes are B wind. If you think about how a cassette works with the heads contacting the tape as it passes through the "window" of the case if it was A wind like reel to reels, the heads would have to be located inside the case.
So, tapes meant to be played in the standard radio station "cart machine" are also B wind. I've never seen them delivered on large reels but I would say that these tapes were meant to be sliced and loaded into cart machine cases for daily use. If you've ever seen the abuse that media takes in your typical radio station you'll appreciate the wisdom of using cartridges.
BTW, this is just my best guess.

[astrotoy]

I think I remember finding a tape wound that way once. What I remember doing is after mounting the tape on the left hand reel, I twisted the tape one half turn, so the oxide side was facing correctly, then threaded the tape the normal way to the other reel. I then played the tape (not fast forward), so the tape wound correctly onto the other reel. You can then wind it onto another reel as needed if you want it to be heads or tails out. I don't think there was a problem with the tape creasing.   Larry

[ironbut]

Yep, the truth be told, I did that accidentally to one of my Tape Project tapes (gulp!). I realized what had happened after I stopped the rewind at the leader. There was some edge damage since it doesn't get quite as nice a tape pack anymore but the tape still sounds fine. Kinda scary!

[Tubes n tapes]

Tj,

Do you know where these tapes originally came from? In the German broadcast industry it is quite normal to have a B-wind. Most of the Telefunken M12 and M15 machines, the standard machine for the German broadcast, were configured for B-wind. After Telefunken discontinued their tape recorder production, Studer developed a replacement machine, custom made for the German broadcast industry, the A816. This machine, based on the A820, also has the heads on the outside of the tape.

In your case I would first rewind the tape and then play it back with a half twist in the tape. After that you're set.
(It is best to use a machine that has quite some distance between the reel and the first tape guide.)

[Teeg]

  After taking a good look at the tapes, it turns out that only a handful (from the same series) are incorrectly wound. Since several of the tapes are sealed in plastic and tagged, I would guess they were originally produced like that, but for what market is a guess. All of the songs in this series are mid 80's top 40 stuff, with a short pause and verbal description between each title.  Using the above suggestions, I was able to re-wind the tapes using a twist, and running my ATR slightly faster than normal play with the shuttle control.

  The rest of the tapes all look 'backwards'....shiny brown on one side with an almost black matte-finish surface on the other, which is outside. A friend suggested to spool one up as normal and try it, and sure enough, these appear to be wound correctly and play fine. The odd thing is that whatever type of tape was used (the reels are not marked at to the tape type), the play side is visually deceiving, being the shinier side of the two.  Yet on the top 40 tapes, the oxide is the darker side. If you saw any of the reels side by side, the tape looks identical.

 Wierd, and I spent the better part of Sunday afternoon flipping reels.

Tj

[docb]

The rest of the tapes all look 'backwards'....shiny brown on one side with an almost black matte-finish surface on the other, which is outside. A friend suggested to spool one up as normal and try it, and sure enough, these appear to be wound correctly and play fine.

Yup, that is backcoated tape. The RMGI SM468 that we use is similar in appearance.

[Teeg]

  What is the purpose of the backcoating?

 In standard practice, I add 4 or 5 feet of leader to my reels and was wondering if the backcoating affects the quality of the splice or the materials needed to do it properly.

 I threaded up more tapes last night, and so far the 'B wind' tapes are limited to just a few of the same series, perhaps a dozen. Rewinding them is a slow process and I don't seem to get the best tape pack right after using the half-twist. Running them back onto the original spool after flipping at fast speed seems to pack the spools better, for whatever reason.

Tj

[ironbut]

Hi TJ,
Here's what the tape manufacturers claimed the advantages of backcoating is;

? Provide a smoother wind
? Provide better grip for tape movement
? Provide for electrostatic drain
? Reduce print-through

The actual day to day results vary with formulations of course but I believe the main consideration was the winding and grip parts.
How well the carbon black, that was one of the main components of back coatings, adheres also depends on the binder that was used to attach it to the backing. I don't think there's any way that it could be as strong a bond for splicing tape as no coating, but I find that the life of the splicing tape is usually more relevant. Breakdown of the adhesive into a hard, non adhesive rather than a sticky goo is always preferred though. I really don't know if there's any adhesive that lasts forever.

[docb]

Rewinding them is a slow process and I don't seem to get the best tape pack right after using the half-twist.

Yeah, the half twist method is dicey at best. Not only do you run the risk of the twist traveling into the pack and creasing or stretching the tape, as you found the tape tension and alignment with a twist in the tape is enough different to affect the pack. I suspect you could possibly end up with some edge damage as well. I think you are on the right track in doing a rewind after the twisting process, though I would usually recommend a play off at slow speed rather than a fast wind.

[ironbut]

Here's a stupid tape trick that might be best for you. I was thinking that the best thing would be to avoid as many tape guides as possible and if you could isolate it to moving guides, all the better. Unfortunately this stupid tape trick will only work on rewind or ff but I think that it should work pretty well and be fairly quick.

Take a piece of adhesive tape and hold the right tensioner down just enough to fool the machine into thinking that there's a tape threaded ( so it'll rewind/ff). Leave just enough loose so you can pull the tape off when the tape is done. Put an empty reel on the left (supply side) and your full reel on the right. Put your twist right at the full reel. Thread the tape under the right tensioner and over the second one making sure the twist stays between the full reel and the right tensioner. Then secure the end of the tape on the empty reel like usual. Keep your fingers crossed and hit rewind. The twist should stay between the reel and the right tensioner and the surface that the tape edge comes in contact will be turning so it should do a minimum of damage.
WarningRemember, the adhesive tape will keep the machine from knowing when the tape ends so you need to pull it off to stop the machine (that's what the loose end is for).
I tried this without the twist so let us know it it works with one.

We're all praying for you!

[Teeg]

  That sounds like a reasonable idea, but I'll have to work up the courage to try it (!)

 Hows this for kicks.....I have a spare 440B transport; it is just a parts deck but it does work. I'll disconnect the left side motor and adjust the brake for just a small amount of drag.....just a minimal amount......the full reel will go here with the tape leading off of what would normally be the wrong direction. The tape will thread across (no headblock installed), thru the capstan, and onto the empty reel, all at normal play speed.

 I doodled the tape path on paper and it looks OK, but perhaps this is best tried with a reel of junk tape first.

Tj

[ironbut]

To add to the backcoating post,..
I was so engaged with trying to find a 3M bulletin when they first started backcoating their tapes that I forgot some of the background involved. Now that I've had a second, I'll try and paraphrase what was contained in that bulletin.

In an effort to improve American tape the oxide side of the tape was polished. I'm not sure if they realized that what they were doing was reducing scrape flutter but it improved the high frequency. European tape had a reputation as allowing a more consistent wind and this effort was also meant to try and improve tape pack. Well, contrary to their intentions, the polishing of the oxide side made the tape pack worse. The reason for this is it reduced the tiny escape channels for the air that is trapped between the layers of tape so the tape would ride on the trapped cushion of air. In those days the back of the tapes were nice and shinny so the idea was to make the back as rough as the oxide side used to be and everybody would be happy. While they were formulating that coating it was discovered that if the coating was made conductive that the static charge that was caused by the friction of the layers of tape rubbing against each other could be drained through the tape pack, out through the metal reel and the turntable spindle. Another plus since the lack of a charge didn't attract dust as much reducing drop outs.

So, it seems like a win-win and except for the added cost there didn't seem to be any downside to backcoating. Well, unfortunately the problem with backcoating really has nothing or very little to do with the backcoating itself. It came into widespread use around the same time that the binders which result in the dreaded Stick Shed Syndrome were introduced. And some of these tapes which could have been baked and transfered were made much more difficult to deal with since the oxide sides can stick to the backcoating pulling the oxide off of the backing altogether. The correlation between backcoating and SSS was so frequent that there were (and are) those who believed that the backcoating was a causative agent but I've never seen any scientific data linking the two.

[Tim]

This company repairs sticky-shed tapes using a patented cleaning method, not the common baking process.  They claim backcoating is quite involved in the SS syndrome.   I believe part of their repair process is removing the backcoating!

http://rezerex.com/thestickyshedsolution.html