Re: [ARSCLIST] revisiting tape bakers

["Charles A. Richardson" <charlesarichardson@xxxxxxxxxxx>]

Hi Richard:

There has been a continuing discussion of baking as a remedy for  
sticky shed contamination on magnetic tapes.  List members point to  
the Ampex Baking Patent as authority for baking sticky shed tapes to  
enable playback.  The discussion seems to assume the safety or ignore  
the damage that baking does to tapes.  Baking is dangerous and much of  
the information about baking tapes is misleading.  The following is  
not just my opinion or assertion but has been substantiated by the  
scientific analysis of a nationally recognized, independent forensic  
chemical laboratory.

1)  The baking process set out in the Ampex Patent melts the sticky  
shed debris with heat  energy.  This stops tape
frictional squealing while the sticky shed debris remains in a  
liquefied state, but the squealing returns after the debris cools off  
and solidifies once more.  It does not cure the underlying chemical  
causes of the tape problems which return endlessly.

2)  Magnetic tapes are made with complex chains of polymers.  The  
polymer links are extremely heat sensitive.  Baking destroys the  
flexibility of the tape and the binder adhesion because it damages the  
links in the chemical chains.  Applying heat permanently breaks down  
the chain links, causes unwanted new cross linking of chemical bond  
links, and creates new, unwanted chemical compounds.  The tape becomes  
increasingly brittle and the coatings start to flake off the base  
film.  Repetitive baking increases the damage to the chemical,  
magnetic and physical components, and eventually destroys the tape.

3)  Sticky shed debris, liquefied by baking, collects at the tape head  
gap.  This debris accumulation pushes the tape oxide surface further  
and further away from the tape head's surface at the critically  
important head gap.  This collection of debris causes a physical and  
major magnetic separation loss, which, as you know, severely reduces  
the ability of the tape head gap to magnetically scan the short wave  
lengths of the oxide's recorded content at high frequencies.  This  
results in inferior mechanical, magnetic and sonic playback  
performance and thereby a deficient transfer of tape content.  The  
playback head's high frequencies are greatly reduced, the noise  
reduction system playback performance mis-tracks, and worsens these  
high frequency losses. Thus the tape sound quality is now made dull  
and lifeless because sticky shed debris on the head gap magnetically  
attenuates proper and complete scanning of the important high  
frequencies that are now greatly reduced or even missing altogether.

4) Baking causes increased print-through.

5) Baking causes weakened magnetic fields and thus lower flux and  
output signal levels.

6)  Baking does not provide any "restoration" or "rejuvenation" of  
binder chemicals.  To the contrary, it causes progressive
and permanent damage to and destruction of the tape.  A fundamental  
thermal law of chemistry is that heat energy destroys
substances.

7)  Baking is not a safely repeatable solution.  Each time a tape is  
baked, it requires higher temperatures and/or longer bake times.  Each  
round of baking produces worse chemical, physical, magnetic,  
mechanical, and sonic results.

8)  The high heat used in baking drives off by evaporation the light  
weight polymers and causes the magnetic particle material attached to  
them to fall off.

9)  Baking the tape damages the tape's magnetic content and seriously  
degrades the playback performance.  People have ruined tapes by baking  
them, but this is generally not admitted, possibly because of fear of  
liability and potential loss of income.  They may be unaware of any  
other method to stop tape squealing safely and permanently.

10)  Some proponents of baking try to rationalize this dangerous  
baking method by inventing a new set of terminology and
circumstances, such as "soft binder syndrome", to justify using the  
baking technique to obtain a mediocre playback.  I am unaware of any  
scientific evidence or support by an independent laboratory for "soft  
binder syndrome" as either being separate and distinct from or a sub- 
set of sticky shed syndrome.

11)  The accurate standardized chemical terminology is that tape  
binders are inherently hygroscopic, and thus are susceptible to  
hydrolysis.  The only safe and highly effective method to restore and  
preserve tapes suffering from hydrolysis of the binders, or sticky  
shed syndrome, is to first, put the affected tapes in a stable  
environment of low heat and humidity for as long as it takes to  
reverse the hydrolysis reaction, and then second,  safely clean all  
the tape's debris from both the oxide surface without damaging the  
surface, and also completely remove its chemical material causal  
source, namely the deteriorated carbon black back coating.

12)  Much reliance has been placed, or should I say misplaced, on the  
Ampex Baking Patent.  The Ampex Baking Patent is intended solely to  
expedite the transfer of recorded information.  The title, "Restored  
magnetic recording media and method of producing same", is inaccurate  
because the baking method does not  take steps to preserve the media,  
but only to restore temporarily a "playable condition" in the media.   
It is merely a band aide fix, not a cure.

13)  The 1993 Ampex Baking Patent suggests that heating tapes to  
120-130 degrees Fahrenheit "does not further deteriorate the tapes"  
and implies that baking a tape for prolonged periods of time is safe.   
The patent does not cite scientific or chemical evidence to back the  
"no further deterioration claim".  Moreover, the claim runs directly  
contrary to pre-existing chemical thermal laws and 1980 scientific  
findings that heat damages tape's magnetic content by increasing print  
through levels, published in a scholarly article written by Ampex's  
own staff scientist, H. Neal Bertram.  "The Print Through  
Phenomenon" (JAES Volume 28, Issue 10, pp.690-705; October 1980).

14)  The elevated temperatures stated in the Ampex Baking Patent,  
120-130 degrees, also violates Ampex's own tape manufacture's warranty  
limiting heat to not exceed 90 degrees.  This chemically abusive high  
baking heat radically shortens tape lifespan to a small fraction of  
the time tapes can last if they are instead stored and handled as  
chemical science requires.  Tapes have the ability to be reliably  
archival for a very long time.  However, if abused by improper  
storage, handling, and wrong headed restoration, then tapes are  
damaged, degraded, and destroyed far ahead of their time.

15)  As you know, a patent does not confer a certification or  
implication that an invention is scientifically proven to be effective  
or safe.  A patent is a grant from the U. S. government (or other  
authority in other countries) of a right to exclude others from  
making, using, or selling one's invention and also includes the right  
to license others to make, use or sell it.
A patent application is only narrowly and formally reviewed to  
determine whether the invention is entitled to be granted a patent  
under U. S. Patent law.  The most important requirement under U. S.  
Patent law is that the invention be a new or useful process, machine,  
manufacture, or composition of matter, or any new and useful  
improvement thereof.  Clearly, a  patent, baking or otherwise, is no  
scientific authority and no certification of safety.

16)  Richardson Magnetic Tape Restoration is concerned, not just with  
minimal baking type partial recovery of the magnetic content  
information contained within a sticky tape, but with the long term  
preservation of magnetic tapes as the primary or original source of  
the all the magnetic content information on the tapes and to create  
optimal playback conditions for high quality reproduction needs.  To  
achieve this goal, RMTR hired a nationally recognized independent  
forensic chemical laboratory to test chemically and to examine under a  
high power electron microscope, the sticky shed tapes, before and  
after application of baking heat treatments.  The lab results showed  
significant deterioration of the tape after it was heated as per the  
Ampex baking patent.  Application of heat treatments, the chemists  
concluded, accelerates even more damage from hydrolysis, and increases  
the cross linking of the polymers used in making the PET Mylar base  
film and binder components of the tapes.  This baking practice soon  
"leads to unwanted tape destruction."  The chemists also concluded  
that the new RMTR process was both safe and effective for tape  
restoration, preservation, and playback mastering needs.

I have a written paper that elaborates on these concepts.  The paper  
is available on request.

If you or any other list members have independent chemical laboratory  
research that refutes these points or supports baking as both safe and  
effective for the restoration and preservation of magnetic tapes, I  
would appreciate seeing it.

Charles A. Richardson,  RMTR LLC




































On Sep 27, 2008, at 8:42 PM, Richard L. Hess wrote:

> At 08:05 PM 2008-09-27, Tom Fine wrote:
>
> > I forgot if Richard has a complete list of must-bake types on his  
> > website. If so, I'm sure he'll provide a link.
>
> I do and your points that I snipped are important for those who  
> haven't heard them before.
>
> http://richardhess.com/notes/2007/03/21/soft-binder-syndrome-and-sticky-shed-syndrome/
>
>
> Richard L. Hess                   email: richard@xxxxxxxxxxxxxxx
> Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
> Detailed contact information: http://www.richardhess.com/tape/contact.htm
> Quality tape transfers -- even from hard-to-play tapes.