Conserving the Collection – Multi Spectral Imaging Microscopy

Following on from Emma Bonson’s blog last week on using X-Ray to investigate blocked plates,  Ellie Pierce, a conservation student at the University of Lincoln, continues our conservation series by telling us about her experience of using a Multi Spectral Imaging Microscope to investigate the plates.

Thanks to Ellie for today’s piece…

On Monday the 14th August Emma Bonson, Ellie Pearce and Rebecca Hawkridge were excited to have the opportunity to see how a Multi Spectral Imaging Microscope is used in the Conservation and Restoration laboratories at the University of Lincoln. Although more commonly used in medicine and biology the MSI is also used in the analysis of painted surfaces. The lady in charge of the microscope; Hollie Morgan- uses the MSI to investigate medieval finger prints and wax seals. However we used the MSI to investigate faded handwriting on envelopes and possible remaining images on the emulsion side of the glass plate negatives.

In very simplified terms a Multi Spectral Imaging Microscope works by omitting different wavelengths of the electromagnetic spectrum through a microscope onto the chosen object. This means that the MSI is able to see details on objects that we may not be able to view through our visible vision.

A diagram of the electromagnetic spectrum

Some of the negatives are in abysmal condition. So much so that there is complete image loss where the silver salts and gelatine have come into contact with damp/fluctuating temperature/relative humidity during their time in the basement. The original envelopes which the negatives were housed in ended up sticking to the emulsion and fibre removal is near impossible without removing the emulsion- a conservation nightmare! Emma, Ellie & Rebecca had hoped that the MSI may be able to detect whether any image was present on the negative.

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Emma Bonson observing new information on an envelope.

Many of the original envelopes also have writing on the envelope which is vital to understanding the collection. Some of the writing on the envelopes has faded, is too difficult to read or has become obscured over time meaning important information loss. We selected a few envelopes for investigation.

We tested one negative that had adhered to the envelope to try and see if we could see an image through the envelope, unfortunately in this case the MSI did not detect any subjects in the picture. However the MSI was very useful in viewing the faded writing on another envelope which was not visible to the human eye. “Bottleyew walk, Downs Convent, Hayle” was detected under the MSI which was extremely exciting as it gave us a wealth of information that we did not have before! This also made sense to us as there are other negatives taken at Down’s Convent. Success!

  Envelope with faded writing and MSI image showing enhancement of writing

We tried another negative which we viewed from the non-emulsion side which we had removed the front section of envelope but the back piece was still adhered to the emulsion surface. When the negative is observed under normal lighting there is barely no image present – just a black surface. However, under a yellow light with a wavelength of 590 we were able to see much more of the image than previously. We observed a rather grandiose room filled with a fire place, portraits, frames, a table with a Gramophone on, a wicker basket, a bookcase and a telephone. We were all blown over with how much we could see.

Viewing the negative with the naked eye (left) and positive detail of the negative under the MSI

Thanks go to Dr Lynda Skipper for arranging for Hollie Morgan to come and work with us. It was a great experience to meet Holly and to see what astounding work her microscope can do!

 

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