This blog post is part of a series about storage relocation and improvements that we are able to undertake thanks to a grant from the Institute of Museum and Library Services.
In the course of our work as conservators, we get some very exciting opportunities. Thanks to a partnership with Hitachi High Technologies, for the past few months the conservation lab here at The Henry Ford has had a Scanning Electron Microscope (SEM) with an energy-dispersive x-ray (EDX) spectroscopy attachment in our lab.
What does this mean? It means that not only have we been able to look at samples at huge magnifications, but we have had the ability to do elemental analysis of materials on-demand. Scanning electron microscopy uses a beam of electrons, rather than light as in optical microscopes, to investigate the surface of sample. A tungsten filament generates electrons, which are accelerated, condensed, and focused on the sample in a chamber under vacuum. There are three kinds of interactions between the beam and that sample that provide us with the information we are interested in. First, there are secondary electrons – the electron beam hits an electron in the sample, causing it to “bounce back” at the detector. These give us a 3D topographical map of the surface of the sample. Second, there are back-scattered electrons – the electron beam misses any electrons in the sample and is drawn towards a positively-charged nucleus instead. The electrons essentially orbit the nucleus, entering and then leaving the sample quickly. The heavier the nucleus, the higher that element is on the periodic table, the more electrons will be attracted to it. From this, we get a qualitative elemental map of the surface, with heavier elements appearing brighter, and lighter elements appearing darker.
Conservation Specialist Ellen Seidell demonstrates the SEM with Henry Ford Museum of American Innovation volunteer Pete Caldwell.
The EDX attachment to the SEM allows us to go one step further, to a third source of information. When the secondary electrons leave the sample, they leave a hole in the element’s valence shell that must be filled. An electron from a higher valence shell falls to fill it, releasing a characteristic x-ray as it does so – the detector then uses these to create a quantitative elemental map of the surface.
A ‘K’ from a stamp block, as viewed in the scanning electron microscope.
The understanding of materials is fundamental to conservation. Before we begin working on any treatment, we use our knowledge, experience, and analytical tools such as microscopy or chemical tests to make determinations about what artifacts are made of, and from there decide on the best methods of treatment. Sometimes, materials such as metal can be difficult to positively identify, especially when they are degrading, and that is where the SEM-EDX shines. Take for example the stamp-block letter shown here. The letter was only about a quarter inch tall, and from visual inspection, it was difficult to tell if the block was made of lead (with minor corrosion) or from heavily-degraded rubber. By putting this into the SEM, it was possible a good image of the surface and also to run an elemental analysis that confirmed that it was made of lead. Knowing this, it was coated to prevent future corrosion and to make it safe to handle.
Elemental analysis is also useful when it comes to traces of chemicals left on artifacts. We recently came across a number of early pesticide applicators, which if unused would be harmless. However, early pesticides frequently contained arsenic, so our immediate concern was that they were contaminated. We were able to take a sample of surface dirt from one of the applicators and analyze it in the SEM.
An SEM image of a dirt sample from an artifact (left) and a map of arsenic within that sample (right).
The image on the left is the SEM image of the dirt particles, and the image on the right is the EDX map of the locations of arsenic within the sample. Now that we know they are contaminated, we can treat them in a way that protects us as well as making the objects safe for future handling.
We have also used the SEM-EDX to analyze corrosion products, to look at metal structures, and even to analyze some of the products that we use to clean and repair artifacts. It has been a great experience for us, and we’re very thankful to Hitachi for the opportunity and to the IMLS as always for their continued support.
Louise Stewart Beck is the project conservator for The Henry Ford's IMLS storage improvement grant.
While researching the many electrical objects being digitized as part of the Institute of Museum and Library Sciences grant, a few stories have stood out to me. These stories sometimes involve the people behind the scenes: manufacturers, inventors, etc., and other times are about how the object was used. Below are four such objects and their stories.
This Jenney Electric Motor Company rheostat has uncovered an interesting story about the company’s namesake. It was designed by Charles G. Jenney who was awarded a patent for it in 1892. Jenney, originally from Ann Arbor, Michigan, moved to Fort Wayne, Indiana with his father to design and produce electrical equipment for the Fort Wayne Jenney Electric Light Company. On February 27, 1885, Jenney, who had been contracted to the Fort Wayne Jenney Electric Light Company by his father while still a minor, successfully petitioned to be removed from the company, and, a month later, he founded the Jenney Electric Light Company later the Jenney Electric Company. The Jenney Electric Company was demonstrating Jenney’s dynamos, arc lamps, and incandescent lamps by August that same year. This company was bought out and Jenney started again, this time with the Jenney Electric Motor Company in 1889 for which he produced electrical equipment like this rheostat, filed for more patents, and wired and lit the streets of Indianapolis.
Designed by Fredinand Buchhop optician and the optician Emil B. Meyrowitz this uniquely shaped motor powered electric drill was used for nasal surgeries including septum operations and electro cautery. On March 3, 1891, Meyrowitz and Buchhop patented the motor, but were only able to patent the globular shape. Even though the motor was crudely constructed, it was portable enough to be useful in the operating theater and at the patient’s bedside.
During the latter half of the nineteenth century, Professors William E. Ayrton and John Perry collaborated on many electrical device inventions including electric railway devices, and electrical measurement instruments including this ammeter. Ayrton and Perry personally certified the accuracy of their meters, and they were touted as being among the most reliable meters during a test in 1886. The London, England-based company, Latimer Clark, Muirhead, & Co., Limited manufactured this Ayrton and Perry Ammeter made between 1883 and 1890.
Last but not least, an electric contactor that required a bit of sleuthing to uncover the correct patents and court cases. According to a tag on this electric contactor, it was used as part of General Electric’s defense when they were on trial for infringing on Sundh Electric Company’s patents. The contactor was part of patent 969,738, which described a new method of operating and controlling electrically controlled switches with an electric motor. This contactor would have been provided in conjunction with the auxiliary switch arrangement to be used on the resistance controlling contactors during operation. Sundh Electric Company thought General Electric’s switch mechanism was too similar to their own, but their patent did not include a contactor resembling this object. Additionally, Sundh Electric Company improved upon an already existing patent prompting the court to side with the defendants, which allowed both patents to remain valid. Laura Lipp isCollections Documentation Specialist at The Henry Ford.
One of the main components of The Henry Ford’s IMLS-funded grant is the treatment of electrical objects coming out of storage. This largely involves cleaning the objects to remove dust, dirt, and corrosion products. Even though this may sound mundane, we come across drastic visual changes as well as some really interesting types of corrosion and deterioration, both of which we find really exciting.
An electrical drafting board during treatment (2016.0.1.28)
Conservation specialist Mallory Bower had a great object recently which demonstrates how much dust we are seeing settled on some of the objects. We’re lucky that most of the dust is not terribly greasy, and thus comes off of things like paper with relative ease. That said, it’s still eye-opening how much can accumulate, and it definitely shows how much better off these objects will be in enclosed storage.
Before and after treatment images of a recording & alarm gauge (2016.0.1.46)
The recording and alarm gauge pictured above underwent a great visual transformation after cleaning, which you can see in its before-and-after-treatment photos. As a bonus, we also have an image of the material that likely caused the fogging of the glass in the first place! There are several hard rubber components within this object, which give off sulfurous corrosion products over time. We can see evidence of these in the reaction between the copper alloys nearby the rubber as well as in the fogging of the glass. The picture below shows where a copper screw was corroding within a rubber block – but that cylinder sticking up (see arrow) is all corrosion product, the metal was actually flush with the rubber surface. I saved this little cylinder of corrosion, in case we have the chance to do some testing in the future to determine its precise chemical composition.
Hard rubber in contact with copper alloys, causing corrosion which also fogged the glass (also 2016.0.1.46).
Hard rubber corrosion on part of an object – note the screw heads and the base of the post.
This is another example of an object with hard rubber corrosion. In the photo, you can see it ‘growing’ up from the metal of the screws and the post – look carefully for the screw heads on the inside edges of the circular indentation. We’re encountering quite a lot of this in our day to day work, and though it’s satisfying to remove, but definitely an interesting problem to think about as well.
There are absolutely more types of dirt and corrosion that we remove, these are just two of the most drastic in terms of appearance and the visual changes that happen to the object when it comes through conservation.
We will be back with further updates on the status of our project, so stay tuned.
Louise Stewart Beck is the IMLS Project Conservator at The Henry Ford.
If you’ve ever walked by the conservation labs at the back of Henry Ford museum, you’ve probably seen the conservators at work on a variety of objects, of a variety of sizes. With a grant from the Institute for Museum and Library Services, we are primarily working on “bench-top” objects – which can be picked up and moved by hand. There are, however, a handful of extra-large objects that we have planned to work on over the course of the grant, including (but not limited to!) historically significant motors, electrostatic producers, and transformers. These objects are important within the electrical scope of the grant, and they need work to be stabilized and preserved for the future. Note that “extra-large” for us is a lot different than extra-large for the rest of the museum – the Allegheny is magnitudes larger than anything we are working with, for example! The “extra-large” objects that we are working on range up to 2 tons in weight, and require specialized equipment such as forklifts to move. We draw the line at artifacts requiring specialist rigging or outside contractors. These sorts of objects do bring their own issues – moving them from one place to another is difficult and requires careful planning, they require a good deal of space in the lab, and the treatments can take a significant length of time. We’re moving at a quick pace with the work on this grant, so taking up two to three weeks just working on one object isn’t a good solution for us.
The first extra-large object we’ve grabbed, viewed top-down – a Sprague streetcar motor.
So how do we balance the amount of time it takes to treat very large objects with the need to keep up a pace in order to achieve completion goals? We’ve tackled this perrenial problem in an interesting way. Since we don’t have an enormous number of extra-large objects to complete, we are allowing three months for the conservation of each. What this means practically is that we can bring the object into the lab, give it a space, and then as we have breaks between work on smaller objects, we can dedicate a few hours to it here and there. Breaking up the conservation work in this way has been very successful so far!
The first object that we’ve treated in this way is a Sprague streetcar motor. This is a really interesting and important object, believed to have been used in Richmond, Virginia on the first major electric street railway system, and dating to the end of the 19th century.
Two of the coils on the motor before treatment.
In the image above are shown two of the coils on the motor before treatment – the textile covering was loose and dirty, and in some places the damage extended to the layer below the outer wrapping as well. The treatment for this object required not only cleaning, but repair to these areas of damage.
Their ‘tails’ have been rewound and reattached, and the dust and dirt have been removed. The area around the coils has also been cleaned and the wire wrappings have been tidied. The engine overall is nearing completion, but does have some areas that still need cleaning. It’s been great to have it as a project we can come back to for small spurts of time, which is exactly what we were hoping for our extra-large object treatment plan.
Louise Stewart Beck is an IMLS Conservator at The Henry Ford.
We are about 35% of the way through our 24-month project to digitize 900 artifacts from our electrical distribution collections, thanks in large part to a generous grant from the Institute for Museum and Library Services (IMLS), and nearly 100 objects from the grant are currently accessible through our Digital Collections.
Outside that project, but on a related note, we’ve just finished digitizing 132 photos of figures associated with the same companies as the objects we’re digitizing in the grant. For example, now you can see images of people associated with Westinghouse Electric Company, and also find objects created by that company, most of which were conserved and photographed through the grant. One intriguing image we found is this 1880 photograph of Thomas Edison associate Charles Batchelor, which notes it is “the first photograph ever taken by incandescent electric lamps.”
Visit our Digital Collections to see all of these portraits of electrical pioneers, and keep an eye out for more artifacts digitized through the grant to be added over upcoming months. Ellice Engdahl is Digital Collections & Content Manager at The Henry Ford.