Flattening maps

Michael Mccolgin <mimccol [at] dlapr__lib__az__us> wrote

>Do any of you have any experience in
>humidifying and flattening large quantities of oversize materials?

For the most part, flattening maps is a very easy thing to do.  I have
flattened many maps, but none that were laminated or mounted on cloth.
My experience only covers rolled or folded paper.

Quoting from Books, Their Care & Repair by Jane Greenfield:

   "A paper document that has been stored rolled or folded is
    disinclined to lie flat.  (Disinclined is an understatement.)
    Flattening is one of the first steps in treating it.  Humidifying
    relaxes paper: if is allowed to dry under light pressure, it will
    usually stay flat.

A simple humidifier is described on page 41.

Humidifier

Any closed container large enough to hold a wet sponge in a saucer and
the material to be humidified without their touching each other will
serve as a humidifier.  A simple, effective one was invented by the
conservator, Carolyn Horton.  It consists of a plastic waste basket
inside a plastic trash barrel, with about 6" of water in the trash
barrel.  Empty the barrel and leave the top off when you are not
humidifying.  Wash both waste basket and trash barrel occasionally with
soap and water.  A sign on the cover of the trash barrel, reading "This
is not trash.  Do not empty." is advisable."

To humidify:  Place the material to be flattened on end in the waste
basket.  Place the waste basket in the waste barrel (which has the 6" of
water in the bottom).  Cover the waste barrel with the accompanying lid
or a large garbage bag cinched up tight around the waste barrel.  Leave
the paper in the waste basket until it is limp and slightly damp.

Check the paper periodically.  the humidification process can take from
half an hour to a day or two as different papers water at different
rates.  In some climates mold can be a problem and must be taken into
account.

Once the rolled or folded object has absorbed moisture, gently unroll or
unfold it.  Use cloth covered weights to hold it in position.  I have
large pieces of blotter paper and Hollytex I use to build a microclimate
so the paper will dry slower.  (I've always felt that if the paper dried
slower, it would retain a flat "memory" better.  I have no scientific
proof for this belief.)  My sandwich usually consists of large sheets of
blotter paper, Hollytex, the object, another layer of Hollytex, another
layer of blotter paper and a large sheet of Mylar to hold the moisture
in longer.  Any material like Hollytex (material that will allow
moisture to pass through and not damage the paper) could be used.

I usually flatten maps on the top of large map case or on a corner table
in the Reading Room.  I use 3/8" pieces of glass with ground edges to
weigh the maps down.  These pieces of glass are in various shapes so I
can select ones to fit the map.  Some institutions use table-sized
pieces of plexiglass and add weight on top.  If I feel I need weight, I
use paper covered bricks.

Often a map will dry overnight.  If I am worried about having enough
space to flatten a map or being in the way, I wait until Thursday or
Friday and flatten over the weekend.  It is very important that the
paper be completely dry before reshelving.  If the map is cool to the
touch (I often touch the paper to my cheek as it's more sensitive than
my fingers) it is still damp.  The blotter paper can be changed to
hasten drying or it can be left to air dry for a longer period of time.

I have often humidified  several maps at one time and stacked them on
top of one another to dry.  I have never had a problem but if a map
seems too fragile for that, do each one individually.

Artemis BonaDea
Conservation Technician
Alaska State Library
Box 110571
Juneau, AK  99811
907-465-2924
Fax: 907/465-2990

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                  Conservation DistList Instance 8:52
                  Distributed: Monday, January 9, 1995
                        Message Id: cdl-8-52-004
                                  ***