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Contributors: Katherine Holbrow, Kimi Taira.
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Copyright: 2011. The Objects Group Wiki pages are a publication of the Objects Specialty Group of the American Institute for Conservation of Historic and Artistic Works. The Objects Group Wiki pages are published for the members of the Objects Specialty Group. Publication does not endorse or recommend any treatments, methods, or techniques described herein.
Rare earth magnets in conservation
With the development and commercial availability of rare earth magnets, these super-strong materials have now entered the conservation toolbox. The use of magnets by conservators is still in its infancy, but many strategies are being explored. Magnets can be used as clamps to mend three-dimensional objects such as baskets, or to reshape flexible materials such as leather or textiles. They provide a temporary, yet powerful hold which can be creatively applied in many situations.
Caution: Rare earth magnets are extremely strong. Handle with caution as they can fly together and pinch fingers and art. Do not use them near art works until they have been securely encased in mat board or other insulating material to prevent unplanned movements. Rare earth magnets are easily altered by heat. Do not use hot glue or other heated materials that may affect the magnetism. Remember that they are metal: do not use corroded or damaged magnets for display mounts, and always make sure that the artwork is isolated from contact with other metals by layers of archival or inert material.
As artists and museums develop new styles of art and exhibition, new exhibition methods must also be developed. Conservators have developed several methods for using these magnets to secure art and artifacts on display mounts. When properly selected and prepared, the magnets can gently press an artifact or artwork against a mount board, and hold it in place by means of a second magnet or steel panel hidden inside the mount. The artifact is secured by pressure alone, eliminating or reducing the need for hinges, pins, and stitching.
Magnet mounts offer one solution for presenting very large works on paper or textile when a traditional mat or frame is not suitable. By embedding the magnets in strips of mat board, the magnetism is dispersed and controlled, and the result is visually similar to a narrow window mat. Removal takes only a few seconds, and by constructing mount boards in standard sizes many of the components can be reused in future installations. While magnet strips are not the answer to every installation need, in some cases they can provide an efficient, strong, and safe means of securing art.
The steps that follow describe construction of a magnet mount for an oversized contemporary Chinese painting. This type of work (ink on a single large sheet of paper) can present display challenges: the artist did not choose to protect the work with a traditional hanging scroll format, but to frame it in a western-style wood frame may be visually jarring. The example is based on magnetic mounts installed at the Asian Art Museum of San Francisco in 2010-11, where they are often used to support Chinese paintings, thangkas, costumes, and other artworks.
Construction of a magnetic mount for flat art
The first step is construction of a backing board, with strips of sheet steel beneath the padding and fabric. The artwork will be secured to this backing board using the magnetic strips described in step two.
- Rigid board (e.g. D-lite or Coroplast)
- 26-gauge Galvanized Steel Metal
- Aluminum Tape
- Double-stick Tape (e.g. 3M #415)
- Exhibition Fabric
- 2- or 4-ply Rag Board (optional; used as a “cushion” beneath the exhibition fabric)
- Flannel (optional; used if the exhibition fabric is not deemed thick enough to support a textile)
- Ethafoam (optional; used for pinning textiles to the board)
Tools and hardware
- Pop-rivet Gun
- Aluminum Pop-rivets (recommended grip range of .313-.375 or .188 - .250 inches; recommended hole size of both is .129-.133 inches.)
- Aluminum “donuts” (to secure Pop-rivets in place)
- D-rings (2-3, depending on the dimensions of the mount)
- Handheld Power Drill
- Hot Glue Gun
- Fabric Scissors
- Wall Cutter
- Aluminum Compound Board blade
Verify Mount Dimensions
Particularly if this is a custom-made mount, it is a good idea to double check the dimensions of the artwork to make sure that the mount will be appropriately accommodating to the piece. Cut the D-lite board to size- in the event that the dimensions do not fit within the 4’ x 8’ distributor’s size, fit pieces together, reinforcing the back with a strip of D-lite (+/- 8”) along the back seam and aluminum tape along the front.
For the standardized flat textile mounts, there are two 10” horizontal steel strips along the top and the bottom, which cover the points of support for the textile. For the standardized paper mounts, the steel is the exact dimensions of the D-lite to accommodate a large array of sizes. These sheets are custom-cut by the distributor.
Install D-rings to D-lite board
Pre-drill the holes, then install with pop rivets. Make sure that the flush side is on the face. Our extended loop reaches at least 1 5/8” from the top edge to hide the hanging fixture behind the board.
Attach materials together
Using double stick tape (a fairly generous amount) to adhere the steel to the D-lite. Seal the edges with Aluminum tape, making sure to smooth out any inconsistencies or air bubbles. Tap the corners with a hammer to blunt the edges; it isn’t meant to round the edges, but simply prevent the D-lite/steel from cutting the fabric.
Cover Board with Exhibition Fabric
At this point, if a flannel/ethafoam/mat board layer is desired, it should be installed now. The flannel can be adhered around the back edges of the board with hot glue; the mat board can be applied with double stick tape; the Ethafoam can be adhered with either. Much like the other mounts, tension and alignment are of utmost importance. Make sure that the size of the fabric compensates for the depth of the mount in addition to 2” for the pullover and adhering. The idea is to make the fabric act as a second skin to whatever it is covering- not tight, not loose, but snug around the form. With the mount face up, center the fabric into place. As you lay the fabric down, there are a couple of ways of refining/fixing the alignment.
Suggestion 1: use a ruler (also use for partitioned pieces of fabric)
This is particularly useful if you have the salvage edge to work with since it’s presumably fairly straight with the rest of the threads. Essentially what you’re aiming to do is measure the edge of the fabric to the edge of the mount where it begins to overlap.
Suggestion 2: thread alignment (along corners, also good to use in conjunction with the ruler)
Starting from the center edge, tack the fabric into place with tape; this will be your anchor point for the rest of the alignment. The threads of the fabric may be difficult to discern, depending on the type of fabric with which you are dealing. For example, in the case of velveteen, it’s easy to identify the weave of the fabric, whereas some of the thinner cotton fabrics are harder to follow. Give or take 2-3 strands, follow this “grid” along the edge as you tack.</p>
Compound Oversized-Horizontal Supports
In one case, we needed a panel that measured 59” by 86”, but due to the angle of the sliding doors of the pre-existing exhibition case, it was easier- and safer- to split the panel vertically in half.
[Illustration with explanatory supports needed]
For additional rigid support, the D-lite can actually be mounted directly to a wooden strainer. This also provides a stronger way of supporting joining edges, particularly on oversized mounts because the D-lite can be cut to meet along cross-sectioning beams. The procedure is the same, except to adhere the fabric, to the strainer, a staple gun has been effective.
Magnet strip construction
The following procedure outlines the process to create 5/8” wide and 40" long magnet strips. These, in particular, are used for most works on paper in conjunction with the magnet board (see above).
- 2 sheets of 2-ply mat board, in exhibition color
- 1 sheet of 4-ply mat board, at least 6” long
- Jade 711
- 3/8”rectangular magnets (.75” x .375” x .0625”, NdFeB, Grade N40, Ni-Cu-Ni finish, Magnetized through the Thickness, Poles on Flat Face)
Tools and hardware
- Rulers/Straightedges (36” or longer)
- Several weights (to keep for flattening)
- Protractor (MicroLux 8”)
- Plastic Triangle
- Olfa Blade
- Wall Cutter, short blade
- Scrap mat board
Precut 4-ply strips
One set is approximately 6” long by the exact width of the magnet; the second set is 3” long by the exact width of the magnet, and the “finishing” set are ¾” wide and as long as the length of the entire sheet (in this case, 40”). It’s important that the last set is a continuous piece since this edge will show. These internal pieces are cut adjacent to each other to attempt to compensate for any variations that happen while cutting the strip, thus theoretically fitting together when glued together.
Assemble magnets and adhere facing layer
Starting with the left side, begin assembling along the bottom edge of a 2-ply sheet in the following order. In this configuration, about 6 magnets will fit on a given 40” strip.
As the strips are constructed, local weight is applied for as long as possible to diminish warping. Glue the 2nd sheet of 2-ply on top of all the magnets, effectively creating a magnet sandwich. Particularly when this piece is adhered, it is important to have a flat surface and a large covering board with weights on top to ensure that the strips dry without distortion.
Adjust the lengths of the magnet strips. To accommodate the piece, you should have the exact dimensions of the artwork, which in turn determines if you need to add another strip back-to-back or if you need to slice down a 40” strip.
When cutting down a strip (use an extra rare-earth magnet to determine where the embedded magnets are), do not try to cut through a magnet- not only will it damage the magnet, it is extremely difficult. In many cases, it’s easier (and better) to cut and adjust within those 6” gaps. Ideally speaking, there should be magnets fairly close at both ends of the strip, but also be aware that the corners need to meet exactly at 45 degree angles.
Install work on mount
When positioning the work on the mount, the idea is to center it on the board. This can be started with non-precise visual judgment, but when you are ready to place the magnet strips, use a ruler to measure all margins. Also for added protection for the piece, add a layer of Photo-tex between the piece and the board. It should be slightly smaller than the exhibited item, ~1/16” less on all sides.
Making the long-mitered strips are effective for a permanent, standardized mount size. However, if there is a larger mountboard to accommodate objects of various dimensions, it may be easier to fabric right corners, which would also ensure the proper amount of pressure for the edges of the piece. This method would also allow for easier customization through varying the long strips without having to potentially modify with a 45 degree cut.
Heavier weight-bearing version: Thangka
The procedure is the same, but the change in materials and spacing are as follows:
- 2 sheets of 2-ply mat board, in exhibition color
- 1 sheet of 8-ply mat board or equivalent (in this case, cut into .75" x 28" strips and .3125" x 2.25" spacers)
- Jade 711
- 3” rectangular magnets (.3125” x 3” x .125”, NdFeB, Grade N40, Ni-Cu-Ni (Silver in color) – Magnetized through the Width, Poles on the Long Edge)
Particularly for strips using these longer, larger magnets, the junction between the magnet and spacer is susceptible to creasing or eventual breakage of the matboard enclosure. A working model is being refined and tested to provide extra support. The latest test uses a thin cellophane tape to wrap the vulnerable points, followed by an overall layer of linen tape to prevent abrasion from the edges of the plastic carrier.
Internal Assembly Order
Craddock, A.B. 2004. Construction Materials for Storage and Exhibition. Conservation Mounting for Prints and Drawings: A Manual Based on Current Practice at the British Museum., ed. Joanna M. Kosek. London: Archetype. 23-28.
Gatley, S. 2009. The InvisiblesV&A Conservation Journal 57: 4-5.
Kosek, J.M., 2004. Conservation Mounting for Prints and Drawings: A Manual Based on Current Practice at the British Museum. London: Archetype.
Spicer, G. 2010. Defying Gravity with Magnetism. AICNews 35(6): 1, 3-5.
Taira, K. 2011. Magnet Mount Procedure. Asian Art Museum Conservation Technician Handbook. Unpublished. San Francisco: AAM.
Derbyshire, A., and T. Tallean. 2005. The New Miniatures GalleryV&A Conservation Journal. 51.
Keynan, D., J. Barten, and E. Estabrook. 2007. Installation Methods for Robert Ryman's Wall-Mounted Works. The Paper Conservator 31:7-16.
Rayner, J., J.M. Kosek, and B. Christensen. 2005. Art on Paper: Mounting and Housing. London: Archetype.
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