Hi Katie:

I'm actually agreeing with you -- definitely treat the exhaust as "hostile" and definitely take the 
precautions you deem necessary. I wouldn't say it's like running a car in a closed garage 
(guaranteed to kill you eventually), but who knows and why be risky in a workplace? And, as I said, 
they don't smell nice (not bad like a skunk, but definitely not pretty like a flower). As in all 
things, I try to be moderate in my approach. Vent hood, yes. Clean room, no.

See my separate post about which tapes to bake. I never bake something that's not exhibiting SSS 
and/or is clearly of the suspect types. There are ways to tell without damaging the tape. If you 
understand the history of a tape type -- what era certain boxes are from, etc -- that's a helpful 
start. For instance, if I get a brown-gray Ampex 406 box, really good bet it's sticky. If I get a 
Quantegy-branded 406 box, maybe but not definite, usually not so far in my experience (other 
experiences may vary). Scotch 226/227 was all sticky. So was Scotch 250, I believe. I've encountered 
old (supposedly pre-SSS) reels of Ampex 406 that were greasy and tacky-oozy but not outright stuck 
together. Those responded well to baking, not sure why since the binder is supposedly different. A 
classic SSS tape will be stuck together right from the get-go. Once you get experience with them, 
you'll note that they smell a certain way and there's kind of a greasy feeling to the edge of the 
tape pack, sometimes you can see little bits of ooze at the edge if you look with a magnifier. If 
you're able to un-wind a few feet of tape from a suspect brand, likely SSS should feel some what 
greasy and tacky. I wouldn't wind it any further, I'd bake it because experience tells me it needs 
it and if it's not stuck together at some point, it is greasy and tacky and will not ride well in 
the tape path.

Here's why I wouldn't bake Scotch 206, for instance, or Maxell UDXL, unless it was clearly stuck or 
oozing. Those tape types are known to get "stiff" over time, similar to what happens to early 
brown-oxide polyester tapes but perhaps to a lesser extent because the brown-oxides are older and 
not enough time has passed for the 206 and Maxell tapes. So far, the "stiff" tapes don't have 
problems playing, but Scotch 206 can definitely get so dried out that it sheds oxide, as can 
Audiotape polyester-backed brown-oxide tape. My belief is that these tapes shouldn't be exposed to 
dry forced hot air (ie baking). In fact, I question whether they -- or earlier acetate tapes for 
that matter -- should be stored in bone-dry conditions as is recommended for known SSS types.

So I'll stick by my recommendation that only SSS types should be baked. At this point, if you have a 
SSS type from the known SSS years, it will be well stuck and clearly need baking. I haven't read or 
heard of damage being done to those types from before and after the SSS era if they, too, are baked, 
so you can do that to keep your workflow simple. I would definitely not bake known non-SSS types and 
if they are stuck I would question whether it's actually SSS. Early brown-oxide non-backcoat 
polyester tapes have never shown SSS, as far as I know, so I would say it's inappropriate to bake 

-- Tom Fine

----- Original Message ----- 
From: "[log in to unmask]" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, February 20, 2012 5:06 PM
Subject: Re: [ARSCLIST] offgasing from baking tapes

" 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.""

Hi Tom:

I agree with the first statement, but not the second. i'm obligated to follow safety regulations to 
the best of my ability in order to protect not only my employer but myself - and I had an employee 
express concern about the effects of baking tape, which is how topic this came up for me -- so I'm 
pretty comitted to toe-ing the OSHA required line here.  If I were in business for myself, or even 
just doing the baking myself, I'd be a little more relaxed about how and when to employ controls, 
and do it all in the most practical way.

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."

Thanks for the info!

"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."

I thought baking wan't employed at all for acetate tapes, for this reason?


----- 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.