In this talk, objects conservator Carolyn Riccardelli introduced us to carbon fiber fabric and shared some of the ways in which this material has been used for the conservation and mounting/display of objects at the Sherman Fairchild Center for Objects Conservation, Metropolitan Museum of Art (MMA).
The first part of the talk focused on explaining what carbon fiber fabric is and its various uses outside the museum world. It was primarily used in the 60’s and 70’s for aeronautics but is now found its way into many industries such as automotive and sporting goods. Though the widespread adoption of this material wasn’t seen until the late 20th century, carbon fibers have been around since the late 19th century. The first commercial carbon fiber was created by Thomas Edison in 1879 for use as a filament in the first incandescent bulbs. Edison’s carbon fibers were made through the heating of cotton threads or other cellulosic materials. Today’s carbon fibers are made from polyacrylonitrile (PAN).
Carbon fibers are chosen over other fiber reinforced composites, such as fiberglass, when high strength is needed but the material needs to remain lightweight. Some advantages that carbon fiber fabric has that may make it a better option over other materials are:
- the fibers are conductive
- they are very small, about 5-10 microns in diameter (smaller than a human hair!)
- they are chemically resistant
- they are very strong
- they have low thermal expansion
There are different ways that you can buy carbon fiber fabric and Carolyn has purchased it as a fabric and a tape from the company Fibre Glast. For the work that’s been done at the MMA using this material, the two most common carbon fiber products have been 6K 5HS satin weave carbon fabric and carbon fiber tape (non-adhesive backed).
Carolyn offered up some tips for the use of carbon fiber fabric for those of us who may consider trying out this material after hearing her talk. Some of the helpful things she pointed out were:
- Be careful when choosing resins for laminating carbon fiber layers. Different resins can be used but she has primarily used epoxies to ensure strength and rigidity. The epoxy she has purchased is sold by Fibre Glast and is the one the company recommends for use with carbon fiber fabric, the System 2000 epoxy. Carolyn did mention some people have used epoxies from West Systems, however these are not for high performance applications. She stressed the importance of using resins made specifically for carbon fiber fabric because this would ensure that the composite system will perform the way it should, especially when needed for supporting a lot of weight.
- Several layers of carbon fiber fabric are needed for create a strong enough composite fabric. For the carbon fiber tape, which is good to use when you need strips of support material, 3 layers have generally been enough.
- In certain cases, when the composite layer of carbon fiber fabric and resin is quite thick, power tools, such as a rotary cutter, can be used to cut away or shape the material. When doing this, you should wear a mask, and you should always wear gloves when handling carbon fiber fabric.
After introducing to what carbon fiber fabric is, its advantages and offering tips for its use, Carolyn walked us through some projects at the MMA where this material was used.
Tullio Lombardo’s Adam
For the reconstruction of Tullio Lombardo’ sculpture of Adam, carbon fiber tape was used to create external armatures and straps during the fitting of fragments. A corset and flange was made out of carbon fiber to help support Adam’s torso. The use of carbon fiber for the treatment of this sculpture can be seen in the video After the Fall: The Conservation of Tullio Lombardo’s Adam as well as the time lapse video Conserving Tullio Lombardo’s Adam: Time-Lapse showing the reconstruction of the sculpture.
Della Robbia’s Prudence tondo
For the Prudence tondo created by artist Andrea della Robbia, carbon fiber was used to aid in mounting the heavy glazed terracotta object. The brass mounts that had been used previously to support the object were no longer strong enough. Therefore, Carolyn turned to carbon fiber fabric in order to create a much stronger, but lightweight, support. Clips were made out of 7 layers of carbon fiber fabric which were laminated together using epoxy. After creating the clips and bending them to the shape needed to support the tondo, they were painted so they were not visible when the object was viewed by the public.
Turtle shell mask, Torres Strait Islands
The final example Carolyn talked about was the use of carbon fiber fabric for the repair of a turtle shell mask from the Torres Strait Islands. The mask was made from thin sheets of turtle shell shaped, carved and decorated to depict a human face with a frigate bird on top. The bird appears to be in flight and the wings protrude to either side. One of the wings was damaged and required repair. The repair material needed to be strong to support the wing, but also needed to be light weight. Carbon fiber fabric seemed to be the perfect material. Pieces of carbon fiber fabric were laminated together using epoxy (Epotek was used for the carbon fiber layers in contact with the object and epoxy from Fibre Glast for the other layers). Once the laminated support was created, it was adhered to the damaged area using Paraloid B-72
In closing, Carolyn brought up some things one should consider before purchasing carbon fiber fabric for a project or treatment:
- What is your budget? – Carbon fiber fabric is expensive and it takes several layers to create a laminate thick enough to provide enough strength and support
- Do you really need that level of rigidity or such a stiff material? – If not, maybe something like fiberglass based fabric might be a good alternative.
- Will you be using this material in contact with a metal? – Because carbon fibers are conductive they can promote galvanic corrosion of the metal substrate.
- Will you be using this in contact with a sensitive material or in a closed environment? – Carbon fiber tape (and likely some of the epoxies used in the lamination process) have not been Oddy tested so it is something to keep in mind when using this material.
Carbon fiber fabric looks to be a really useful material when one needs a strong material for support, that can easily be molded to fit the shape of an object, but still needs to be lightweight. The various examples from the MMA highlighted some interesting applications for this material. I look forward to seeing more presentations in the future on how carbon fiber fabric can be used in objects conservation, and hope to get my hands on some to begin experimenting with it in the lab.