Extreme Close Up

Picture of a man wearing glasses sat in front of two computer screens. He is in a lab. His hand is stretched out towards the screen on the right. Beside the computer screens is an SEM machine. Above it is a Warning sign depicting a yellow triangle with an exclamation mark in the middle.
Peter Gethin operating the SEM machine.

Did you know that felt can be made from the fur of animals, such as beaver, wolves, rabbits and deer, as well as from wool? Pressure, heat and moisture are applied to the fur which encourages the fibres to grip together. This creates a highly durable yet flexible fabric – perfect for making hats! As part of our redevelopment at Hat Works we’re dedicating a space to exploring the fascinating process of making felt from fur. In the name of creating some exciting content for this space Emma and I found ourselves on a train to Liverpool carrying a backpack stashed with ten bags of animal fur.

We were heading to the Department of Archaeology, Classics and Egyptology at the University of Liverpool to meet with Senior Archaeological Technician Peter Gethin. We’d been in contact with Peter who said he could produce SEM images of our fur samples.  What on earth is an SEM image? It’s a super close up image produced by a Scanning Electron Microscope. For reference, this microscope looks like a large, glorified coffee machine. Peter assured us that, like driving a car, it’s not necessary for Emma and I to know how the machine works, just what we can do with it.

The simplified gist of it is: electrons travel down the microscope from an electric circuit at the top and strike the sample. They bounce off and are detected by sensors. These sensors produce a close up image of the sample on a computer screen. When I say close up I mean that we could see the ridges, cavities and bends on the surface of individual fur fibres. On some of the fur samples that had been treated as part of the felt-making process (this was often done with the highly poisonous chemical mercury), you could see splits down the middle of them fibres. On others the scales on the fibre were pronounced and open, allowing them to better mesh together to make felt. With their high contrast colouring and soft patches of light, the images were oddly beautiful. Peter told us that one of his students had had a selection of SEM images of metals blown up onto canvases.

To our excitement Peter explained that if we coat the fibres in gold it will produce clearer images. This is because gold is a good conductor so attracts the electrons with a strong force. The fur samples were coated in a 5 nanometre layer of gold using a Quorum machine. Peter told us he’d been searching for something intricate to look at using the SEM and a student had suggested he use a spider that had died in the corner of the room. We were equally thrilled and horrified. He showed us the spider, poised in a clear case, coated gold.

Picture of a hand holding a clear plastic box in which is a dead spider coated in gold. It's legs are curled under it and it's body is shiny from the coating.
The dead spider coated in gold.

Staff and students popped in and out of the SEM room whilst we were working. We explained to them what we were doing and they explained to us what they were working on. One student’s area of study was Egyptian mirrors and another’s was Roman coins. It was clear that the SEM machine was highly valuable to their research and as the only large-chamber model in the university, clearly a pride to the department. Peter said his love for SEM was sparked when an eccentric professor took a bogie out of his nose, put it under the microscope and showed him his skin cells wiggling about on the screen.

Without having seen the fibres under the SEM we would never have known that there were threads of cotton mixed in with the fur samples or that they were coated in copper chloride. One of the functions of the SEM is that is can run an analysis of the chemical composition of the samples. Peter explained that in the past he has worked with museums to detect whether there are any corrosive chemicals in an artefact that can damage it over time. Also, to assess the levels of arsenic and mercury in artefacts to check they are safe to handle by museum conservators.

Having left Peter to process our fur samples we headed over to the Garstang Museum of Archaeology, which has many ancient artefacts from Egypt and Sudan. After an information-heavy morning we let off some steam playing dress-up at the museum.

I found I looked at the displays differently after learning about SEM. Scientific technology and the work of museums are intensely linked, both in the conservation of artefacts and to create exciting learning experiences. We are so looking forward to bringing you our specialist display on fur felting when we re-open.  

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