From: AirSpace <noreply+feedproxy@google.com>
Date: Sat, Sep 5, 2015 at 6:21 PM
Subject: AirSpace
To: pascal.alter@gmail.com
AirSpace |
| Conserving Wiley Post's Helmet Posted: 05 Sep 2015 07:00 AM PDT The experimental helmet, worn by famed American aviator Wiley Post to test the limits of high-altitude flying, can normally be seen at the Smithsonian Institution Building (The Castle) on the National Mall in Washington, DC. When white corrosion deposits were noticed on the metal, however, the helmet was removed for examination and treatment. It was sent to the Museum's Emil Buehler Conservation Laboratory in Chantilly, Virginia. The helmet has a significant place in history as a part of the world's first practical pressured flight suit. Post, along with Russell S. Colley of B.F. Goodrich, developed the suit so that Post could experiment with high-altitude flying in his aircraft, the Lockheed Vega 5C Winnie Mae, which had an unpressurized cabin. He used it in flight for the first time 81 years ago today (September 5, 1934). We know that the helmet is composed of an aluminum alloy with fabric that was treated with dope, a paint that when dry helped to make the fabric airtight. A sheet of clear plastic was used to create the face plate. And a very thin layer of nitrocellulose lacquer was applied to the aluminum exterior surface that helped prevent the aluminum from corroding. In areas where the protective coating was not applied, thick white and light brown colored corrosion deposits have formed.  Wiley Post's helmet prior to conservation treatment. Photo: Sharon Norquest, Smithsonian Institution  This photograph highlights some of the aluminum alloy corrosion on the back of the helmet. Photo: Sharon Norquest, Smithsonian Institution The first thing we wanted to do was to learn more about the corrosion products and coatings on the helmet. To do so, we examined the helmet under ultra-violet light. This was incredibly exciting to see. So many materials on the helmet fluoresced. The bright orange color on the handle and mouth plate are cadmium corrosion products. Bright white spots were seen on the back of the helmet toward the center and are from the aluminum corrosion. The whitish haze on the aluminum surface is remnants from a thin and failing coating. The dope, which is often a nitrocellulose lacquer or a cellulose acetate coating, could be seen as a bright green color on the fabric.  These photographs of the helmet under ultra-violet light were taken before conservation treatment. The ultra-violet light photography helped to highlight different areas that were coated or exhibiting signs of corrosion. Photo: Sharon Norquest, Smithsonian Institution Examining the helmet under ultra-violet light helped us determine our course of treatment. Our first step was to remove the thin and failed coating from the aluminum. Next, the cadmium and aluminum corrosion products were removed to help stabilize the metal. The corrosion products were removed both mechanically with abrasive pads and scalpels as well as with solvents applied to cotton swabs. After the corrosion products were removed, the metal surfaces were degreased with solvents and a new coating of a cellulose-based lacquer was applied to the metal. This coating will act as a moisture barrier and prevent new corrosion from forming. Dents in the metal were noted in past historical documents as being original so they were not altered during the treatment. While the doped fabric is stiff from all of the coating applications, it is in good condition overall. Because of this, the fabric was not altered during our treatment. After the conservation treatment was complete, the helmet was returned the Smithsonian Castle for display. Once again, visitors can examine Wiley Post's helmet and imagine what it might have been like to fly in the world's very first pressure suit.  The helmet after conservation treatment. Photo: Sharon Norquest, Smithsonian Institution Sharon Norquest is a conservator in the Collections Department of the National Air and Space Museum The post Conserving Wiley Post's Helmet appeared first on AirSpace. |
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