Mounting oversized collage

I have been asked by a local museum to design an exhibition mounting
system for a huge, relatively new collage (1995) and would
appreciate suggestions (including things not to do).  It is 23 feet
horizontally, 6 feet tall.  I have seen only the outer edge--it is
stored on a large rolling tube.  If all the object is similar, it is
made by adhering together pieces of billboard papers, each about 4"
x 6" in irregularly cut sizes.  These pieces are at least several
deep on the backing, which is not one continuous piece, but joined
pieces of what felt like reasonably strong paper at this time. The
collage pieces are not adhered smoothly-- the object has a puckered
topography. I have no idea what adhesives may have been used.  I do
not know how much the whole  weighs, but the end felt heavy when I
lifted it (possibly from adhesive?).  We can calculate weight
distribution when that is needed.  The edges of the piece are
ragged.  It will not be objectionable if there is some
undulation/unevenness in the mounted surface.

The museum has added this object to its collection.  Therefore, I
think it is desirable to aim for a mounting system that can remain
behind the object indefinitely, rather than go back and forth
between exhibition and storage systems.  The object will spend most
of its life in storage so I hope to design a storage system that can
be put on exhibition for several months at time.   Since storing the
collage rolled seems undesirable  due to the puckered construction,
inherently weak papers, and possibility of creating curves, it seems
preferable to store the object flat, face up, despite its size.  The
museum probably could accommodate this, although the idea of a huge
object atop aisles of storage units does not appeal to the staff.
The museum could use a mock-up to ascertain whether the mounted
object could be moved through doors, elevators, etc.

I have learned of non-magnetic metal panels that could be attached
to the gallery wall or mounting panel and would accept magnets
placed over the back of the collage.  I don't yet know what a panel
surface 23' x 6' would weigh, and I don't know whether flexible
magnets placed in bands or spots across the back of the object would
be strong enough to hold it upright.

My thoughts have also turned to Velcro-type strips, although I
understand that they shouldn't be left in contact with objects
indefinitely.  (Interleaf strips could be adhered between either
magnets or Velcro and object.)

I am thinking of using horizontal strips across the width of the
collage, with a vertical distance between strips somewhat less than
what we calculate the strips could bear.  Does anyone have thoughts
about the likely success or failure of such a design?  What are the
hazards I haven't mentioned/foreseen?  Is there a better option
altogether?

A colleague recommended some kind of hinges across the top and down
the sides (slit/carry-through hinges or wrap-around hinges secured
by local magnets, which would allow for adjustments as the object
moves);  but I'm afraid any hinging system would be inadequate for a
heavy, weak surface 23 x 6'. For the same reason, I worry about the
viability of a hanging rod in a cloth casing. That is why I have
been aiming at support in horizontal bands, like cames across
stained glass windows.

Any recommendations for the mounting panel material?  Ideally, it
would be lightweight, acceptable for long-term proximity, and
physically relatively tough so art handlers could move it between
storage and the gallery without punctures or dents.
Any guidance will be greatly appreciated,

Christine Smith
Conservation of Art on Paper, Inc.
703-836-7757
Fax: 703-836-8878

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                  Conservation DistList Instance 12:75
                  Distributed: Tuesday, March 23, 1999
                       Message Id: cdl-12-75-016
                                  ***