A while back I forwarded a query on flattening paper to Conservation On-Line.
 Here is one response that I have received to date.  Apologies to those who
are cross-posted:


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Forwarded message:
From:   [log in to unmask] (George Leake)
To:     [log in to unmask]
Date: 97-04-23 16:31:48 EDT

[please realize I am not a professional conservator, simply technical staff
in Preservation work with 12 years experience]

    I recently ran across this description of removing warps from
    paper in the following way on a genealogy newsgroup. Can anyone
    offer a critique of this method?
*indeed. I will critique away (my comments prefaced with *)

 A better method or reference guide?
*it should be obvious here that what's causing the uncurling is the use of
humidity. Clearly there are many better and safer options. A sealed chamber
or area of some size with a humidifier going. Instrumentation should be set
to gauge RH%. IMHO, relative humidity should be gradually increased.
Obviously a more contained environment like a vacuum chamber might be best.
Although even a cigar humidor would be better (again, IMHO) than this! As
far as reference guides go, I know of none offhand


       "I have worked with curled photographs and folded documents
*very important point here. The conservators here at the Ransom Center have
always made this point about paper--it tends to have a memory. One wonders
quite seriously whether folded and curled documents or photographs might
not be apt to curling back up later on even after they're relaxed--paper
has a memory, and dry conditions can cause tightness in many media.


        successfully in the following way: I purchased a very large
        plastic container like you use to store sweaters or a
        blanket. I then put distilled water in the bottom of this
        container. (about 1/2 inch). Take a pie pan or bowl turned
        upside down in the middle of the container.[I like to use
        ones that are small even so that the lid will still close
        but the documents have room not to be touching the cover]
        (this makes a surface where the document can stay but
        doesn't get into the water)  Place the photo on the pan/bowl
        and cover the container. Let it sit anywhere from 12 hours
        to a day or so. (Don't forget it!)
*the problem with this set up is obvious. What keeps the document(s) from
falling in the water, or the water splashing the document?

*one hazard of all uses of humidity to relax paper and other media is of
course the promotion of mold


Once the document has
        absorbed the moisture usually I can unfold it or unroll the
        photo.  You must then immediately place it between wax paper
        or photographic blotting paper and put a very large book on
        top of it.
*the blotting paper sounds good, though what we tend use is more a board.
Which gets changed after at hour intervals, all depending on amount of
moisture. For pressure, we use pressing boards and cloth covered lead
weights.


  Let it dry that way. I wouldn't try this with
        anything that is too crumbly, mostly I've worked with rolled
        photos or folded fairly solid paper documents."
*again, one needs to keep an eye to general conditions in one's
institution. Does the RH% change with the weather, or do you have control
(or can have it) over  environmental conditions?

"Responsibility is what awaits outside the Eden of Creativity." -- N.
Gordimer


George Leake
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