Window Lids for Large, Heavy Flat Objects and Specimens

Purpose

Keeping dust off of specimens in open storage is always a challenge, but particularly in an old building and an urban environment like Pittsburgh, Pennsylvania. In 2014 the Carnegie Museum of Natural History received a grant from the Institute for Museum and Library Services specifically for improving storage conditions for type specimens in the vertebrate paleontology collection.

One portion of the collection stored on open shelving consists of large specimens, primarily fish and is preserved in a slabs of rock. These specimens are encased in custom built wooded frames, with plaster used to fill in gaps. A lid covering the specimen was made from plastic sheeting stapled to a light-weight wooden frame that sat on top of the rock and inside the wood tray encasing the specimen. The cover’s opaque plastic sheeting made viewing the specimen difficult, especially when it was covered in dust. The plastic lid was very difficult to clean, especially after it began to deteriorate. In addition, removing the lid from the specimen was very difficult, because it lacked handles and rested inside of the frame surrounding the specimen.

A new method for covering the specimens was designed to protect the specimens from environmental damage and to facilitate visual access to the specimens.

Figure 1. An example of a large slab set into plaster. The exposed specimen is the darker minerals, surrounded by matrix and set into plaster.

Author(s)

Gretchen E. Anderson
Carnegie Museum of Natural History
5800 Baum Boulevard
Pittsburgh, PA 15202
412-665-2607
AndersonG@CarnegieMNH.org

Linsly J. Church
Carnegie Museum of Natural History
4400 Forbes Avenue
Pittsburgh, PA 15213
412-622-1915
ChurchL@CarnegieMNH.org

Amy C. Henrici
Carnegie Museum of Natural History
4400 Forbes Avenue
Pittsburgh, PA 15213
412-622-1915
HenriciA@CarnegieMNH.org

Photo Credits: Gretchen Anderson, Linsly Church
Illustrations: Gretchen Anderson

Publication: 2016

Figure 2. The old plastic dust cover is stapled to a wooden frame. The plastic is now opaque and covered with dust. It is also brittle and torn.

Figure 18: The specimen covered by half of the lid. Note how the foam blocks support hold the lid above the specimen

Figure 3: The specimen covered by half of the lid. Note how the foam blocks support hold the lid above the specimen

Figure 19: The specimen covered with the full lid.

Figure 4: The specimen covered with the full lid.

Description

The method developed uses a window in a box lid to improve access to even the largest and heaviest specimens. The method is easily adapted for three dimensional models or objects.

Figure 3. A new box lid with a polyester window cut into it. Note that the frame sits above the fossil, over the outside of the wooden tray. Lift by the edges to remove the lid.

Figure 5: A new box lid with a polyester window cut into it. Note that the frame sits above the fossil, over the outside of the wooden tray. Lift by the edges to remove the lid.

The lid frame, made of acid-free cardboard, fits over the wooden tray and encases the specimen. The lid has a clear polyester sheet inset for a window. The lid protects the specimen from particulate pollution, and the window allows a potential researcher to examine the specimen without having to remove it from the shelf. If closer examination is needed, the specimen can be moved to an open table and the lid easily removed. For very large specimens, the lid can be made in two or more sections that snap together.

With slight modifications the same method can be used to create a cover for models and 3-Dimensional specimens or objects.

Figure 4. This is the extended lid, designed for specimens in trays longer than four feet. The two part lid can be easily slid off either end. There is additional support in the center to stabilize the span of the lid.

Figure 6. This is the extended lid, designed for specimens in trays longer than four feet. The two part lid can be easily slid off either end. There is additional support in the center to stabilize the span of the lid.

Materials, Tools & Supplies

Archival board (acid-free foam core, acid-free cardboard, mat board)
Melinex™/Mylar™ (polyester film) 4ml
3M™ 415 Polyester double-sided tape
Cutting mat
Olfa™ Knife
Straightedge
Square
Clamps
Bone folder
Pencil
Neutral PVA or hot melt adhesive
Tongue depressor

Construction

Standard Window Lid

Figure 5: A diagram of the lid. 1) Cut the blank for the lid (black). 2) Measure and score the sides of the lid. 3) Cut away the diagonals (light blue) for the corners. Note that all cuts are in the same orientation. 4) Measure and cut the window

Figure 7: A diagram of the lid. 1) Cut the blank for the lid (black). 2) Measure and score the sides of the lid. 3) Cut away the diagonals (light blue) for the corners. Note that all cuts are in the same orientation. 4) Measure and cut the window

Accurately measure the specimen including the wooden tray or box. Include the length, width and height. These measurements will be used to create the lid.

Figure 8: Always double check your measurements!
Measure the board. Add about 1/8” to the length and width measured above. Determine the height necessary for the lid sides (2 inches the minimum). Add the sides two times to both the length and width (side + side + length; 2x side + width). Use a straight edge and a square when measuring. The end result is a large rectangle. Make sure that all edges are straight and corners are square before cutting. Cut the board to size.
Mark all sides of the board with the dimensions of the sides of the lid. Example: If the lid needs a 2”side, measure and mark in pencil 2” on all sides. Using a straight edge, score the board with a bone folder, making sure that corners are square. The scored face will be the interior of the lid.
Measure and cut the hole for the window. Leave at least 2 inches from the scored edge to the edge of the window.
Install window. Cut a piece of polyester film slightly larger than the window opening. Apply 3M 415 tape to the inside of lid close to the opening. The polyester film should completely cover the tape. Apply the sheet, being careful to keep it even and smooth. It helps to remove the tape backing from one edge and line up the film. Press it down using a bone folder. Start removing the tape backing on the longer parallel edges while laying the film down. This will help to prevent wrinkles.

Figure 9: Attach the double faced tape. Start at one edge and carefully peel back the silicone release backing and lay the polyester down evenly.
Make sides:
- Fold along scored edges
- Cut corner flaps – always be consistent on where you cut your flaps
- Angle corner flaps. This will strengthen the corners.
- Remove interior corrugation leaving you with 2 flaps (the outer layers) of paper. Use the side of a bone folder to crush the corrugation and peel the flap away from the corrugation.
  
  Figures 10,11,12: Remove Corrugation. Be careful not to tear the paper
Fold sides up and glue flaps. Spread the adhesive evenly on the inner surface of the paper, where the corrugation was. Systematically work around the lid, adhering the outside flaps to the sides first and then moving to the inner flaps. You will effectively sandwich the side between two flaps. Clamp the glued surface to ensure that there is good contact. The corner should be square.

Figure 13: Gluing corners.

Figure 14: The finished lid.

Option: 2 part lids for large flat specimens or object

This lid is constructed for large flat objects that are too large for a single piece of acid free foam core or grey board. A two-part lid is easier to handle and still protects the specimen. Use the same process as described above with the following alterations described below. Use acid-free foam core for the two-part lid because this material is less likely to crease or bend.

Figure 13: Diagram for half of the extended lid.

Figure 15: Diagram for half of the extended lid.

This construction is a little different from the lid described above; though similar, there are a few important distinctions:

Divide the longest measure in half. For each side, add the half-length and 2 sides to the width. Do this for both halves of the lid. Only score and fold one side on the half-length side & 2 on the width.
Remove the foam from the center of the foam core. Use the same technique as described above. A spatula is a handy tool for this task. Be careful not to tear the paper.

Figure 16

Support the seam: Cut a piece of board that is about 4”wide with the length equal to the width of your lid + sides +1/2 inch including the sides. The ½ inch allows for the thickness of the foam board. Score the short ends for the sides of the lid.
Position the seam cover so that only half of the cover is on the lid. Adhere the seam cover to one side of the lid on the outside surface. Adhere the sides. You can use the following adhesives: hot melt glue, pva emulsion, starch paste or 415 tape. This will hold the two parts of the lid together.

: Lid half with the extension. The seam cover is on the outside. Note the foam blocks. This lid was made for a slab with a more 3- dimensional specimen.

Figure 17: Lid half with the extension. The seam cover is on the outside. Note the foam blocks. This lid was made for a slab with a more 3- dimensional specimen.

Figure 18: LId half without extension.

Figure 17: The two halves of the lid put together.

Figure 19: The two halves of the lid put together.

Figure 20: The specimen covered by half of the lid. Note how the foam blocks support hold the lid above the specimen

Figure 21: The specimen covered with the full lid.

Comments

Figure 22: Window lid used vertically for 3-dimensional object

You can use the same system for creating a lid for a larger, 3-Dimensional piece. The measurements change. Measure the length, width and height of the object you wish to cover. Create a 5 sided lid with the techniques used above. Choose one surface to cut a window into. Insert the polyester film window. Seal corners as above.

It cannot be stressed enough that measurements need to be accurate. Cuts should be made with a straight edge and a square. The lid or box will fit much better if this practice is followed.

Adapted From

Gretchen Anderson developed most of the above methods while working at the Science Museum of Minnesota in the 1990’s. Some of the ideas were originally developed after workshops through the Society for the Preservation of Natural History Collection and the Canadian Conservation Institute. More recently, volunteers with experience in book and paper conservation introduced her to the corner closure described above. Technician Linsly Church came up with the extended lid variation while perfecting her technique for this style of lid.

Literature Cited

Northeast Document Conservation Center. 1992. Encapsulation in Polyester Film using Double-coated Tape. In: C. Rose and A. de Torres, eds. 1992. Storage of Natural History Collections: Ideas and Practical Solutions. Society for the Preservation of Natural History Collections. pp. 137-140.

Greene, V. Adaptation of standard Matting Folders. In: C. Rose and A. de Torres, eds. 1992. Storage of Natural History Collections: Ideas and Practical Solutions. Society for the Preservation of Natural History Collections. pp. 149-153.

Campbell, M. W. Support System for Fragile Tree-dimensional Objects: Shadow Puppets. In: C. Rose and A. de Torres, eds. 1992. Storage of Natural History Collections: Ideas and Practical Solutions. Society for the Preservation of Natural History Collections. pp. 152-154.

Fuller, T. A. Blount and C. Bossert. Support System. In: C. Rose and A. de Torres, eds. 1992. Storage of Natural History Collections: Ideas and Practical Solutions. Society for the Preservation of Natural History Collections. pp. 175 -175.

Acknowledgements

Ashley Cox and Carolyn Burns for introducing the new style corners to the department.
Rebecca Newberry, Conservator at Science Museum of Minnesota for all of her support
Institute for Museum and Library Services for supporting the projec