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This is what happened with many 35 mm magnetic films. They sealed the canisters thinking that it would keep the bad stuff out. Instead, it kept the bad stuff in.

Gary

____________________________

Gary Galo
Audio Engineer Emeritus
The Crane School of Music
SUNY at Potsdam, NY 13676

"Great art presupposes the alert mind of the educated listener."
Arnold Schoenberg

"A true artist doesn't want to be admired, he wants to be believed."
Igor Markevitch

-----Original Message-----
From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Steve Smolian
Sent: Wednesday, December 13, 2017 8:27 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Plastic bags around tape reels inside cardboard tape box

In the old days, when I was on the AES Tape subcommittee of the Educational Committee, Del Eilers of 3M voiced the opinion that polyester tape be left unbagged, this to allow the gasses emitted by the ageing tape to escape.  Otherwise, he felt the gasses would accelerate tape deterioration.

Ste3ve Smolian.

-----Original Message-----
From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of John Schroth
Sent: Wednesday, December 13, 2017 1:20 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Plastic bags around tape reels inside cardboard tape box

Hi Mark:

My two cents....which with five bucks, might buy you a cup of coffee at Starbucks!

I'm not sure if moving a tape from 60%RH to a bag, then sealed and stored at lower temps will cause actual dew formation but If the tape will be stored in "close to ideal" storage conditions after play-out, then in almost all situations, you're better to allow the tape to breathe. Do not wrap back in the protective bag then place into the cardboard tape box. Moisture + tape = sticky shed and or mold. The tapes may have come packaged new from the manufacturer that way back in the day, but it's not the ideal storage packaging for archival tape storage.

If the tape base is acetate based (you did not specify the tape base) than this is even more important as a micro-environment such as a bag holding higher than ideal RH, can promote vinegar syndrome. Keeping an acetate based tape in this micro-environment, allows the acetic acid vapor to build up and escalate the breakdown faster. I've seen this in many collections.

Obviously lower storage temps can slow mold and vinegar syndrome breakdown but why take the risk?

Some plastic based tape formulations are more prone to sticky shed than others (see references the like of Richard Hess's website, etc, etc). 
The higher the RH environment that the tape is stored in (for certain formulations and back-coatings), the better the chance for sticky shed problems and the longer the baking time associated for short-term correction of the problem, if another payback of the tape is required at a later date. Again another reason for abstaining from storing tapes in plastic bags.

Plastic wrapped tape reels were NIB packaging from the manufacturer and meant for short-term resale of the product. I do not believe that long-term archival storage conditions were taken into account or ever tested for this packaging. As long as your facility does not present a high liability of water damage from flooding or fire, if feel there is no need for plastic bag storage.

Kind Regards,

John Schroth

MTS

On 12/13/2017 12:06 AM, Mark Campbell wrote:
> I have a question regarding dew point and open reel tape playback and subsequent vault storage.
>
> It is a given that playback of tapes will occur in temperature and 
> humidity conditions that are far from ideal for tape storage...(ideal 
> being something approaching 16 deg C and 30% RH and a good studio for 
> playback is set to be comfortable for humans not tapes  ---22 deg C 
> and  60% RH)
>
> The problem thus arise:
>
> If after playback of a 10" master tape...I dutifully place in back in 
> its plastic bag and then into its cardboard tape box ...in doing 
> so...I have capture a bubble of air which surrounds the tape inside 
> the bag which is at 'studio conditions" (60%RH)
>
> That tape (well bagged and boxed) goes to an hypothetical cold store 
> at (8 degrees 30% RH)
>
> My question is...will the plastic bag hold that 'studio-air' around the tape...and cause dew formation?
>
> And if so...
>
> Would it be best not to use the plastic bag at all...and allow the tape to 'breath' in its cardboard tape box?
>
> I hope to hear from you soon.
>
> Mark Campbell
>
>
>
>
>
>
> ---
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