Cavity Packing: The gift that keeps on giving

Around the NMSC Archeology lab, I’ve earned the moniker of “The Artsy One”. My eclectic background involves a stint in school for Fashion, a mini-career of five years in costume crafts, a lifetime of interest in Art History, 2 years in architecture school, and current school experience as a Fine Arts major. All of that diverse experience has taught me three very important things about myself: I’m good at crafting things with my hands, I have good spatial skills (including the ability to visual three-dimensional forms based on only a two-dimensional image), and I really, really love old stuff.

(NPS Photo)

One of my favorite tasks is cavity packing, and no, it doesn’t have anything to do with teeth. Cavity packing is the task of carving an artifact-shaped hole out of polyethylene foam to protect artifacts that are weirdly shaped or may suffer more damage if allowed to shift around too much. My very first cavity packing task at the NMSC was this jug with a busted bottom.

Since the foot of the jug is missing, it doesn’t really have a natural surface to rest on. The more something like this rolls around in a box, unsecured, the more the surface, especially the unglazed part, is going to flake off in to itty bitty pieces (my NMSC compatriots tell me the technical terms for this is “spalling.”)  What a piece like this really needs is a cozy little retirement home where he can spend the rest of eternity. With proper storage and careful handling, this jug and its new home will still be in much the same condition long after I am dead and gone. Hey, I don’t have any kids, so I’ll take my immortality any way it comes.

The Process

(NPS Photo)

When I first approach a cavity packing project, I determine whether multiple objects can fit in to a single tray, or if an item gets its own luxury suite. Only a few standard sizes of storage boxes and trays are available, and sometimes it’s necessary to house an object alone, like the jug shown above, or this plate on the right.

Our foam blocks come quite a bit larger than our standard 12″ x 14.5″ archival trays, so my first step is to cut down the foam block to fit the tray. Once I have the right size block, I trace around the artifact to get a rough idea of the shape of the area that needs to be removed.

(NPS Photo)

I’m no Michelangelo, but I’ve got a little bit of sculptural experience, and it really comes in handy at this stage. Using hot knives, I carve out a negative impression of the artifact. It can’t be too snug, or else it’ll be hard to remove and doing so risks damage to the artifact. It also can’t be too loose, or the object will shift when the box is moved. There’s usually some amount of refining at the end to make sure everything is just right.

(NPS Photo)

And here’s the completed hollow for the plate! I like to create a defined space for the foot which will help keep the plate in place.

Once this foam is carved, a layer of archival tissue is placed over the foam and tucked in at the edges of the tray so that everything is nice and tidy.

Oh, and that little bow? That’s one of my favorite parts. It’s not just decorative, but also helps us, or any future researcher, remove the artifact from its home without having to lever up delicate edges.

(NPS Photo)

This entire process ensures the long-term stability of the object. I like to consider it a little gift from our Archeology lab to the future.

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About Larisa A.

Larisa served as a Museum Technician for the NMSC between 2010 and 2014. A graduate of Art History at UMASS Boston, they bring an extensive background in art, design, and spatial organization to projects.
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One Response to Cavity Packing: The gift that keeps on giving

  1. Pingback: Happy Halloween from NMSC: Tricks and Treats of Collections Management! | NMSC Archeology & Museum Blog

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