Hypothesis: Pressing causes long-term damage to comics

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A few people in the recent pressing threads in Comics General have thrown out a hypothesis that I suspect is untrue but that my research thus far been able to neither prove nor disprove--that introducing virtually any amount of heat, humidity, and/or pressure to a comic book while pressing it can cause long-term damage to the comic or reduce its life expectancy. I'd like to explore available professional opinions about this which either support or refute the hypothesis.

I'm going to continue Googling the topic and poking around www.loc.gov and www.archives.gov as I have on and off the first few weeks, but so far I haven't found anything particularly compelling. I'm only posting now to share a question I asked to the Library of Congress via their "Ask a Librarian" feature on the site. I used this feature back in 2003 or so to ask whether or not encapsulating a comic in an airtight or near-airtight container such as CGC's case is harmful and got back a pretty useful response; maybe I'll get lucky and get a good response this time as well. Here's the question I asked that they're supposed to respond to within 5 days:

In the comic book back issue hobby there is a controversy surrounding the paper restoration technique of pressing. The major grading certification company for comics, the Comics Guaranty Corporation, normally notes restoration procedures performed to a comic, However, this company does not define pressing as restoration, and one of the common reasons they give for doing this is that because it is difficult or impossible to detect many forms of pressing which do not involve a comic book's disassembly. The topic is controversial because any collector can purchase a multi-hundred or multi-thousand-dollar comic that is already in excellent condition, press it slightly using a dry-mount press or localized heat/pressure, and re-sell that comic for many multiples of the original value, sometimes resulting in profits of many hundreds or thousands of dollars for a relatively small amount of pressing work.

 

I have a few questions involving paper pressing that I'm hoping a conservation professional can answer to help comic collectors resolve some of the controversial issues around the practice. I intend to share the answer with several hundred fellow comic book collectors via message forums located on the Comics Guaranty Corporation's web site and possibly via an article in a comics industry periodical. The questions I have are as follows:

 

- Most people believe that unlike many conservation or restoration techniques applied to paper products, heat and/or humidity-based pressing is undetectable when performed properly by a skilled conservationist. Is this true, or are there known methods for the detection of pressing?

- American comic books published from the 1930s to present have typically been printed on a variety of low-grade groundwood pulp paper stocks. Is heat and/or humidity-based pressing a safe procedure that can be freely and universally applied to any grade or type of paper product when performed by a conservation professional, or can it instead be destructive to some types or ages of paper regardless of the skill of the person performing the work?

- If you know of any historically or culturally significant paper documents or periodicals which have undergone pressing, or any that have specifically been selected to not be pressed, could you please share them? It would be of great comparative use for comic collectors to know what other similar and noteworthy documents have safely undergone this procedure.

I'll post their response when I receive it. If anyone has links to any professional opinions about the safety or harm of pressing, please share the information or research you've discovered.

A few people in the recent pressing threads in Comics General have thrown out a hypothesis that I suspect is untrue but that my research thus far been able to neither prove nor disprove--that introducing virtually any amount of heat, humidity, and/or pressure to a comic book while pressing it can cause long-term damage to the comic or reduce its life expectancy. I'd like to explore available professional opinions about this which either support or refute the hypothesis.

 

I'm going to continue Googling the topic and poking around www.loc.gov and www.archives.gov as I have on and off the first few weeks, but so far I haven't found anything particularly compelling. I'm only posting now to share a question I asked to the Library of Congress via their "Ask a Librarian" feature on the site. I used this feature back in 2003 or so to ask whether or not encapsulating a comic in an airtight or near-airtight container such as CGC's case is harmful and got back a pretty useful response; maybe I'll get lucky and get a good response this time as well. Here's the question I asked that they're supposed to respond to within 5 days:

 

In the comic book back issue hobby there is a controversy surrounding the paper restoration technique of pressing. The major grading certification company for comics, the Comics Guaranty Corporation, normally notes restoration procedures performed to a comic, However, this company does not define pressing as restoration, and one of the common reasons they give for doing this is that because it is difficult or impossible to detect many forms of pressing which do not involve a comic book's disassembly. The topic is controversial because any collector can purchase a multi-hundred or multi-thousand-dollar comic that is already in excellent condition, press it slightly using a dry-mount press or localized heat/pressure, and re-sell that comic for many multiples of the original value, sometimes resulting in profits of many hundreds or thousands of dollars for a relatively small amount of pressing work.

 

I have a few questions involving paper pressing that I'm hoping a conservation professional can answer to help comic collectors resolve some of the controversial issues around the practice. I intend to share the answer with several hundred fellow comic book collectors via message forums located on the Comics Guaranty Corporation's web site and possibly via an article in a comics industry periodical. The questions I have are as follows:

 

- Most people believe that unlike many conservation or restoration techniques applied to paper products, heat and/or humidity-based pressing is undetectable when performed properly by a skilled conservationist. Is this true, or are there known methods for the detection of pressing?

- American comic books published from the 1930s to present have typically been printed on a variety of low-grade groundwood pulp paper stocks. Is heat and/or humidity-based pressing a safe procedure that can be freely and universally applied to any grade or type of paper product when performed by a conservation professional, or can it instead be destructive to some types or ages of paper regardless of the skill of the person performing the work?

- If you know of any historically or culturally significant paper documents or periodicals which have undergone pressing, or any that have specifically been selected to not be pressed, could you please share them? It would be of great comparative use for comic collectors to know what other similar and noteworthy documents have safely undergone this procedure.

 

I'll post their response when I receive it. If anyone has links to any professional opinions about the safety or harm of pressing, please share the information or research you've discovered.

interesting - I'm looking forward to the response. In the interim, can you post their response (or a summary of) to the first question you asked?

"Step 3: Used a hydraulically operated, electrically heated press with a modified stainless steel platen, to bond the composite document into an integral paper unit. A pressure of approximately 0.5 kg/cm2 and a treatment time of 3 minutes at a temperature of 100o C may be used for most book papers. "

Well, in this case it actually improved bonding strength and paper folding endurance as part of a reconstruction effort (using dry leaf casting) from a library fire in USSR.

http://aic.stanford.edu/sg/bpg/annual/v10/bp10-18.html

Looks like libraries are familiar with the technique.

interesting - I'm looking forward to the response. In the interim, can you post their response (or a summary of) to the first question you asked?

http://boards.collectors-society.com/ubbthreads.php?ubb=showflat&Number=240620&fpart=1

The overall verdict of applying heat and pressure to preserve and lengthen life of cellulose paper based materials does not look like a positive one.

From "Handbook of physical testing of paper."

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Another reference:

"Most often the adhesives used in lamination are also acidic. These factors combined with the heat used in this process act to speed up the acid reaction of the document or book page causing progressive deterioration and eventual embrittlement. Therefore, heat-seal lamination is ultimately extremely harmful to records. It is only appropriate for material with a short life expectancy and should never be applied to documents of historical or intrinsic value."

In this case they are explicitly referring to lamination, however, the commentary on the heat component (which is achieved from pressing) is not good.

from Alabama Department of Archives and History:

http://www.archives.state.al.us/officials/conservlamin02.html

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Lamination

A process of reinforcing fragile sheet material, usually using transparent or translucent sheets of plastic or paper. Some forms of lamination such as those using cellulose acetate are considered unacceptable as preservation methods because of high heat and pressure during application, instability of lamination materials or difficulty in removing lamination from the item, especially a long time after the lamination was performed.

http://www.nla.gov.au/chg/gloss.html

Looks like libraries are familiar with the technique.

My past reading and research has shown they're VERY familiar with pressing. I've read at least a dozen references in conservation articles to them performing the technique as routinely as rice paper reconstruction and reinforcement, deacidification, cleaning, etc. I've heard it in use so much that I've always simply assumed it must be safe, but I suppose that was just an assumption. It could be that it isn't universally safe, and that conservationists pick and choose what is a safe pressing candidate.

Over the last week or two I've found at least half a dozen more examples of conservation articles which simply refer to peforming the act of pressing as if it's just a routine procedure, but none go into any detail why and how it was chosen to be done, other than it is often done for conservation, simply so the item will lay flat and not get damaged when it goes up for display. I'm still searching for the smoking gun article that goes into some specific detail about whether or not there are criteria for choosing whether or not to press.

Some forms of lamination such as those using cellulose acetate are considered unacceptable as preservation methods because of high heat and pressure during application

I wonder what temperature ranges are used for lamination? I seem to recall that most paper pressing uses temperatures between 150 and 190 degress fahrenheit.

interesting - I'm looking forward to the response. In the interim, can you post their response (or a summary of) to the first question you asked?

 

http://boards.collectors-society.com/ubbthreads.php?ubb=showflat&Number=240620&fpart=1

thanks for linking that thread - it was a great read!

- Most people believe that unlike many conservation or restoration techniques applied to paper products, heat and/or humidity-based pressing is undetectable when performed properly by a skilled conservationist. Is this true, or are there known methods for the detection of pressing?

- American comic books published from the 1930s to present have typically been printed on a variety of low-grade groundwood pulp paper stocks. Is heat and/or humidity-based pressing a safe procedure that can be freely and universally applied to any grade or type of paper product when performed by a conservation professional, or can it instead be destructive to some types or ages of paper regardless of the skill of the person performing the work?

- If you know of any historically or culturally significant paper documents or periodicals which have undergone pressing, or any that have specifically been selected to not be pressed, could you please share them? It would be of great comparative use for comic collectors to know what other similar and noteworthy documents have safely undergone this procedure.

I'll take a crack at these, since I don't think you're going to get the response you are expecting from the LOC:

1) Some kinds of pressing can be detected because the book was pressed incorrectly, resulting in damage to the book, or because there are creases that are flatter than they might otherwise be (such as a heavily creased and wrinkled book that is unnaturally flat). As to either of these, "detection" is really an educated guess because there are unintentional acts that can cause a book to exhibit the same characteristics in both cases. There are certain localized forms of pressing that can be detected because the paper gets mashed during the process or burned/scorched because someone doesn't know how to use a tacking iron.

But for many kinds of pressing of minor defects, it is not detectable.

2) Heat and moisture will degrade newsprint, especially when used together. The more decayed the newsprint is to begin with, the more dangerous pressing is, whether heat/moisture is used or not. You wouldn't press a book with weak paper because of the risk that you'd split the spine. (You can split the spine of a book with weak paper just by opening and closing the cover - you don't need to put the book into a press to risk damage if the paper is weak.)

If you're doing it to relatively fresh paper, the level of decay in a proper press job using heat and moisture will be negligible because the paper is not exposed to those conditions for very long. On some molecular level, yes, there is some damage occurring to the cellulose chains when you expose newsprint to heat and moisture. But not all pressing requires heat or moisture. And the pressing that does require heat or moisture, if done correctly by someone who knows what to do, is not going to cause any appreciable damage to relatively fresh paper.

3) Pressing is a commonly used conservation technique for all types of paper artifacts. It is a standard step following any kind of aqueous cleaning, as well as to flatten rolled objects (like historical maps) or remove bends from artifacts. Virtually every document that has undergone any kind of aqueous cleaning has been pressed afterward. The procedures used by conservators on historical documents may or may not be the same procedures used by comic book restoration professionals. Your question suggests that you believe that pressing techniques for comic books are limited to one or two techniques. In reality, there are many different ways to press a comic - some harmful, some safe, some in between depending on the level of skill of the person doing it. The one constant is that they all involve some degree of pressure being applied to a comic book in order to flatten what needs flattening. The pressure itself is not going to hurt the comic book unless it is being done incorrectly, such as applying too much pressure to weak paper, or mashing paper when using certain localized pressing techniques.

interesting - I'm looking forward to the response. In the interim, can you post their response (or a summary of) to the first question you asked?

 

http://boards.collectors-society.com/ubbthreads.php?ubb=showflat&Number=240620&fpart=1

thanks for linking that thread - it was a great read!

 

It was an entertaining read, but there is so much bad information in that thread that it makes my head hurt.

Some forms of lamination such as those using cellulose acetate are considered unacceptable as preservation methods because of high heat and pressure during application

 

I wonder what temperature ranges are used for lamination? I seem to recall that most paper pressing uses temperatures between 150 and 190 degress fahrenheit.

Correction - dry mount pressing uses heat near the lower end of that range (190 is unnecessarily hot). Many other kinds of pressing use no heat at all.

You aren't going to find that smoking gun article. The question you're asking may seem like a deep, scientific issue for you, but for a conservator, whether or not to press an artifact tends not to be a huge internal struggle. Their scholarly articles will deal with far more sophisticated topics. Pressing is "Conservation 101."

Looks like libraries are familiar with the technique.

 

My past reading and research has shown they're VERY familiar with pressing. I've read at least a dozen references in conservation articles to them performing the technique as routinely as rice paper reconstruction and reinforcement, deacidification, cleaning, etc. I've heard it in use so much that I've always simply assumed it must be safe, but I suppose that was just an assumption. It could be that it isn't universally safe, and that conservationists pick and choose what is a safe pressing candidate.

 

Over the last week or two I've found at least half a dozen more examples of conservation articles which simply refer to peforming the act of pressing as if it's just a routine procedure, but none go into any detail why and how it was chosen to be done, other than it is often done for conservation, simply so the item will lay flat and not get damaged when it goes up for display. I'm still searching for the smoking gun article that goes into some specific detail about whether or not there are criteria for choosing whether or not to press.

My guess is the far majority of comic pressing would not be done on relatively fresh paper (what would be the monetary purpose); it is likely done on paper from the 70s and backwards. That being the case, your argument seems to corroborate most of the arguments I cited earlier, that being that heat, oxygen, and pressure combine to speed up the acidic reaction and thus, accelerate the process of decay rather than stabilize it.

Although, I agree that experience and technique would greatly affect the outcome (as you mentioned, a cold and dry pressing might mitigate the negative effects). It would be interesting to hear someone with experience in comic restoration chime in to whether or not it is common to use heat and pressure on golden/silver age comics.

I used to remember being horrified at the chart in Gerber's books that discussed rate of decay of comic paper, and how I cringed at the thought of purchasing a golden age comic considering most were close to his chart's point of deterioration. Yet, it seems there are still plenty of nice stable copies of golden age in existence.

My guess is the far majority of pressing would not be done on relatively fresh paper (what would be the monetary purpose); it is likely done on paper from the 70s and backwards. That being the case, your argument seems to corroborate most of the arguments I cited earlier, that being that heat, oxygen, and pressure combine to speed up the acidic reaction and thus, accelerate the process of decay rather than stabilize it.

There is plenty of "relatively fresh paper" that is older than 70s newsprint. Any book with Off White or better page quality (as a general rule of thumb) will be fine. If the paper is cream but still flexible, it's still probably fine. If it smells heavily acidic and feels less than supple, then you really need to start thinking about whether the book should be pressed while still assembled. (Pressing individual folios is fine as long as the paper isn't brittle.)

Although, I agree that experience and technique would greatly affect the outcome (as you mentioned, a cold and dry pressing might mitigate the negative effects). It would be interesting to hear someone with experience in comic restoration chime in to whether or not it is common to use heat and pressure on golden/silver age comics.

You just did.

I used to remember being horrified at the chart in Gerber's books that discussed rate of decay of comic paper, and how I cringed at the thought of purchasing a golden age comic considering most were close to his chart's point of deterioration. Yet, it seems there are still plenty of nice stable copies of golden age in existence.

The chart in the Gerber guides is not at all scientific or even particularly accurate.

You aren't going to find that smoking gun article. The question you're asking may seem like a deep, scientific issue for you, but for a conservator, whether or not to press an artifact tends not to be a huge internal struggle. Their scholarly articles will deal with far more sophisticated topics. Pressing is "Conservation 101."

They're not born knowing that though--they learned it from somewhere. I'm looking for those sources because I'm tired of people using this as yet another argument against pressing in the endless threads on the topic. I'm sure most question anything they do to paper at some point, just to feel better that what they're doing won't get un-done by future conservationists just as it's sometimes their job to un-do the bad stuff that 18th, 19th, and early-20th century conservationists have done to documents.

Would love to hear some good hard facts on this issue.

This is why I don't have any opinions on pressing yet.

I need some solid evidence that pressing is damaging and so far I haven't heard any

You aren't going to find that smoking gun article. The question you're asking may seem like a deep, scientific issue for you, but for a conservator, whether or not to press an artifact tends not to be a huge internal struggle. Their scholarly articles will deal with far more sophisticated topics. Pressing is "Conservation 101."

You aren't going to find that smoking gun article. The question you're asking may seem like a deep, moral issue for you, but for some one looking to make a buck, whether or not to press a funny book tends not to be a huge internal struggle. Their financial gains will deal with far more sophisticated topics. Pressing is "Profitering 101."

Fixed that for ya.

Think that separates a conservator from the rest.

You aren't going to find that smoking gun article. The question you're asking may seem like a deep, scientific issue for you, but for a conservator, whether or not to press an artifact tends not to be a huge internal struggle. Their scholarly articles will deal with far more sophisticated topics. Pressing is "Conservation 101."

 

 

 

 

You aren't going to find that smoking gun article. The question you're asking may seem like a deep, moral issue for you, but for some one looking to make a buck, whether or not to press a funny book tends not to be a huge internal struggle. Their financial gains will deal with far more sophisticated topics. Pressing is "Profitering 101."

 

Fixed that for ya.

 

Think that separates a conservator from the rest.

Since we're trying to have a serious discussion here, maybe you could confine this useless moralizing to one of the other 800 pressing threads?

You aren't going to find that smoking gun article. The question you're asking may seem like a deep, scientific issue for you, but for a conservator, whether or not to press an artifact tends not to be a huge internal struggle. Their scholarly articles will deal with far more sophisticated topics. Pressing is "Conservation 101."

 

They're not born knowing that though--they learned it from somewhere. I'm looking for those sources because I'm tired of people using this as yet another argument against pressing in the endless threads on the topic. I'm sure most question anything they do to paper at some point, just to feel better that what they're doing won't get un-done by future conservationists just as it's sometimes their job to un-do the bad stuff that 18th, 19th, and early-20th century conservationists have done to documents.

Just because a conservator isn't born knowing it doesn't mean that one of them will have done an extensive scholarly article on the topic. Feel free to keep looking though.

Just because a conservator isn't born knowing it doesn't mean that one of them will have done an extensive scholarly article on the topic. Feel free to keep looking though.

I have no expectation of finding an article devoted to pressing--just someone who does more than mention it in passing with the same presumption you alluded to, that it's simply standard practice. One or two sentences with some specific details about when to press or when not to, or some explicit reference that pressing is something that's appropriate for any type of paper, or alternatively that there are times you shouldn't use it.

One of the main jists of the recent pressing arguments which I can't just refute out of hand is that pressing might be fine for sturdier documents, but not for the cheap pulp comics are printed on. This was one of the only useful ideas I was able to extract while quite masochistically reading that latest infinite pressing thread (99.99% of it is the same old drek tho).