Following a recent conversation with a museum who is discussing how to mark their artifact collection, we thought it might be helpful to share some tips about labeling artifacts with their ID numbers.  When undertaking a labeling project, it is most important to remember never to do anything that cannot be reversed or that will cause damage to an artifact. 

Paper artifacts like archives, photos, books - Use a standard pencil to hand write the number onto the piece.  For photos and documents, the back lower right corner is a good consistent location, as is on the page facing the back cover of a book.
Photographs with a slick backing - Contemporary photos with slick or waxy backings don't accept standard pencil well.  Instead, use a pencil specifically designed for marking photos - Prismacolor Premier, non-photo blue. 
Textiles - Write the ID number onto a small piece of Tyvek using a Pigma Micron pen.  Using just two or three loose whip stitches on each end of the label, sew the label onto the textile.  Locate the label at the back of a collar or waistband for a garment, or the back lower right corner of something like a quilt.  Try to use existing stitch holes, or weave the thread under threads that are already visible, rather than creating new punctures whenever possible.  White silk thread is good to avoid any colored dyes and because this thread is smooth.
Objects with stable surfaces (non plastics) - Type ID numbers and print them onto acid free paper.  Ariel font at about 8 point size is easy to read even at the small size.  Cut out the labels.  Put a basecoat layer of Acryloid B-72 on the artifact, put the label onto the basecoat while it is still wet, and cover the label with a topcoat of the same material.  Choose a location that is not obtrusive if the object is on display, and also not likely to be rubbed off (avoid putting a label on a flat bottom - use an edge instead). 
Objects made of plastic - Tie an acid free tag to these objects, or encase them in acid free tissue, polyester sleeves, or boxes.  B-72 does not react well with plastic long-term.

Sometimes, artifacts have unstable surfaces, are oddly shaped, or are too small to mark using the methods described above.  Sometimes the best method is writing ID numbers directly onto pieces like wood objects or onto unglazed ceramics.  Often the use of tags or boxes is the most useful method to employ.  Also, larger pieces like furniture are often difficult to move around to find an ID number during inventory.  While it is still recommended to mark large pieces as described above, also tie a tag to a more visible area like a chair arm or a drawer pull for easy access.  This tag can be removed for exhibition and returned to its place when in storage.

Some museums use barcodes - scanable, often adhesive labels that help with inventory control.  Adhesives can be very damaging to the surfaces they are applied to , and all adhesives dry out and fail at some point causing that label to fall off and the object to be unlabeled.  If using the barcoding system, put the adhesive label onto an acid free tag and then attach the tag to the object, or print the barcodes onto acid free paper and attach them to objects using the B-72 method.

Using these suggestions will help a museum collection labeled safely and consistently.  Please contact the IMA for any additional questions or thoughts about this topic.