At this early stage, it makes no sense to put what might be a disorganized mass of folders into archival quality enclosures. Just buy and use ordinary records storage boxes 10 x 12 x 15 with detached lids and have on hand some ordinary manila folders for any loose materials.
Review all the folders, looking at the labels and annotations on each one. Can you determine whether there was ever a filing arrangement or arrangements that changed over time? Put the folders in the box(es) in that order. Add date range to each folder or other info that will make it more clear what is in the folder. If there is no order, develop an arrangement plan, and talk it over with another person. If you both agree that the plan makes sense, proceed in sorting the materials.
Once you've organized the materials, determine the types and quantities of archival quality supplies you'll need to rehouse the materials. Of course, you may have discovered that not all the materials are of permanent value. Do not discard until the end of the project and have a second person review just to make sure.
The Society of American Archivists sells any number of books that may assist museums with their archives.
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Peter Parker
Portsmouth NH
pjparker@inlookgroup.com------------------------------