I agree with Richard on all of this. I don't know for a fact that SSS tapes being baked makes for 
completely breathable air, but I betcha it's less toxic than walking down an urban street. The 
problem is, they definitely smell a certain way and some people really don't like that odor. I 
usually bake overnight, with the food dehydrator on top of the stove and the vent hood on, mainly 
because my wife really doesn't like the odor and I don't find it especially pleasing. Ampex 456 
smells worse than Scotch 226, to my nose, but that is 100% subjective.

Richard's last paragraph bears repeating and careful consideration. Only tape exhibiting SSS should 
be baked. Baking is not a good "precaution" or "preventative measure." Not at all. It ruins older 
acetate tapes.

-- Tom Fine

----- Original Message ----- 
From: "Richard L. Hess" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, February 20, 2012 2:15 PM
Subject: Re: [ARSCLIST] offgasing from baking tapes

> Hi, Katie,
> In a commercial environment with the inherent liability issues, I would use an outside-venting 
> exhaust fan in the area I was doing tape baking--or perhaps a fume hood. I know that's energy 
> inefficient in Wisconsin winters, so perhaps using outside makeup air or a heat-recovery 
> ventilation system would be a good choice.
> I am more concerned about mold and the related toxins than I am about the tape outgassing, though 
> I can definitely detect the latter when I'm doing baking. I generally bake in a separate generally 
> unoccupied room, but don't pay particular attention to the exhaust issues.
> I bake moldy tapes in my garage in a separate dehydrator. I figure any mold that escapes there 
> will probably find long-lost relatives <sigh>. I also wear a NIOSH-rated respirator when dealing 
> with mold.
> One archive I've been corresponding with used a dust mask and I suggested if they were concerned 
> enough either for health or perception reasons, they should switch to a respirator rather than 
> just a dust mask.
> I am not a toxicologist nor doctor nor chemist, so take this as comments of a casual user.
> Please remember that not all tapes need baking and baking acetate tapes as well as certain other 
> tapes may do more damage than good.
> Cheers,
> Richard
> On 2012-02-20 1:48 PM, Katie Mullen wrote:
>> Hello:
>> We're looking into the particulars of how we would go about setting up a
>> tape baking program in-house. One thing I have not seen addressed in the
>> informal discussions about baking or in the literature is whether people
>> are concerned about exposure to anything potentially harmful (or that would
>> be regulated under OSHA exposure limits) from off gassing during baking,
>> and following that, whether anyone uses controls (such as a fume hood) to
>> mitigate any potential exposures.
>> A chemist who is studying the degredation of video magnetic media recently
>> said in response to my query that among other likely products, "Degradation
>> products of magnetic tape include carbon dioxide, acetaldehyde, vinyl
>> benzoate, carbon monoxide, methane, and benzaldehyde.  Many of these
>> compounds are considerably harmful if inhaled, so I would definitely make
>> an effort to move the baking to a well-ventilated area, or have it
>> separately ventilated." Beyond the general question posed above about
>> concern vs. controls, if anyone has actually measured exposure during
>> baking to the listed components, I would appreciate knowing more about your
>> results.
>> Stories from your experiences baking, or particulars about how and where
>> you do your baking would be much appreciated!
>> Thank You,
>> Katie Mullen
>> Preservation Coordinator,
>> Library-Archives
>> Wisconsin Historical Society
>> 816 State Street
>> Madison, WI  53706-1482
>> PH: 608-264-6489
>> [log in to unmask]
>> Collecting, Preserving and Sharing Stories Since 1846
> -- 
> Richard L. Hess                   email: [log in to unmask]
> Aurora, Ontario, Canada           (905) 713 6733     1-877-TAPE-FIX
> Quality tape transfers -- even from hard-to-play tapes.