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Date:         Fri, 7 Nov 2008 13:00:49 -0500
Reply-To:     Association for Recorded Sound Discussion List
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Sender:       Association for Recorded Sound Discussion List
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From:         "Charles A. Richardson" <[log in to unmask]>
Subject:      Re: revisiting tape bakers
Comments: To: Association for Recorded Sound Discussion List <[log in to unmask]>
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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. > > > > > Richard L. Hess email: [log in to unmask] > Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX > Detailed contact information: > Quality tape transfers -- even from hard-to-play tapes.

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