Tape Thickness

[wkrbee]

Hello all.I have seen some discussion about some tapes causing extra wear/some machines not working well with Brand X/Brand Y/Brand Z.There was some allusion to tape thickness.Maybe you can shed some light on this,( all off the respective mfg.website):
Quantegy 456-1.925 mils,( I have always seen this referenced as 1.5mil)
RMGI 900-2.05 mils
RMGI 911-1.97 mils
RMGI 468-1.89 mils
ATR Magnetics-2.04 mils
Unless some are more abrasive,(first batches of Ampex 499 were a prime example),or the machine can't supply enough bias current,what really is the difference in how a particular machine would handle the tape related to the tape thickness?

 

[miroslav]

I don't think it's just about the physical thickness, but also the stiffness....though with some transports even the small thickness difference is enough to upset the smooth tape handling, or enough so that you need to (if possible) recalibrate the machine mechanically for the different tapes.

You can try several brands/types on a given deck, and without any technical measurements, you can spot which tape moves more smoothly/easily....or if there is one that doesn't.

I've always been very impressed with 911 on my small format deck...but I'm using 499 on my 2", and the machine seems to like it, even though it is considered stiffer than 456. I plan to do another mechanical setup for specific to the 499 just to fine tune it, as I can see it's not 100% optimal, but still pretty solid.

Wait for Beck to chime in...he has more experience with a wider variety of tapes....he can give you more details.

 

[Beck]

Tape thickness categories are generally based on tape film thickness before the oxide and backcoating are added. So most finished 1.5 mil tapes are actually much closer to 2-mil and 1-mil tapes are closer to 1.5-mil. Some base film is thicker and/or stiffer than others, depending on how it’s made and what it’s made of. The base films have been polyester for a long time for any tapes of interest, but there are different types of polyester, so one tape company will use something a bit different than another. Also +9 class tapes tend to have thicker oxide coating and are more abrasive to the tape path. They’re also heavier due to the coating.

Specifications change as manufacturers fine-tune tape formulations, so spec sheets get outdated.

The latest change in tape thickness is ATR tape, and it’s no longer billed as +10. I never really thought of it as +10 anyway. It was always in the +9 class, and now ATR specs it as +9 over 185 nWb/m in the latest literature. There’s significantly less oxide on it now, which could explain that, but might also be tweaking the formulation.

Michael Spitz of ATR said recently that the old pdf spec sheet was wrong and what’s on website now is right, but I don’t think so. If that is so how could someone have left it up for years without catching the error? There’s a mistake in the math because the total doesn’t match the individual measurements on the pdf, but I’m sure the tape has changed in thickness and other ways. For one thing, they made a big deal about it being the first +10 tape from the start, but now the allegedly correct specs say it is +9. Tape formulations have always been nudged and tweaked to improve performance or when sources of raw materials changed and they had to mix the oxide differently. It's no big deal. They don't have to hide that fact. I would rather hope that they changed the tape formulation rather than think they left an inaccurate spec sheet out there for five years.

Also, oxide thickness does impact where the bias current should be, so it all works together.

 

[Dan Ö]

Tape thickness categories are generally based on tape film thickness before the oxide and backcoating are added. So most finished 1.5 mil tapes are actually much closer to 2-mil and 1-mil tapes are closer to 1.5-mil. Some base film is thicker and/or stiffer than others, depending on how it’s made and what it’s made of. The base films have been polyester for a long time for any tapes of interest, but there are different types of polyester, so one tape company will use something a bit different than another. Also +9 class tapes tend to have thicker oxide coating and are more abrasive to the tape path. They’re also heavier due to the coating.

Specifications change as manufacturers fine-tune tape formulations, so spec sheets get outdated.

The latest change in tape thickness is ATR tape, and it’s no longer billed as +10. I never really thought of it as +10 anyway. It was always in the +9 class, and now ATR specs it as +9 over 185 nWb/m in the latest literature. There’s significantly less oxide on it now, which could explain that, but might also be tweaking the formulation.

Michael Spitz of ATR said recently that the old pdf spec sheet was wrong and what’s on website now is right, but I don’t think so. If that is so how could someone have left it up for years without catching the error? There’s a mistake in the math because the total doesn’t match the individual measurements on the pdf, but I’m sure the tape has changed in thickness and other ways. For one thing, they made a big deal about it being the first +10 tape from the start, but now the allegedly correct specs say it is +9. Tape formulations have always been nudged and tweaked to improve performance or when sources of raw materials changed and they had to mix the oxide differently. It's no big deal. They don't have to hide that fact. I would rather hope that they changed the tape formulation rather than think they left an inaccurate spec sheet out there for five years.

Also, oxide thickness does impact where the bias current should be, so it all works together.

Thanks for explaining about tape thickness. I've also been wondering about how come they call it 1.5 mil and not 2 mil.