Microscope Techniques in Your Museum

Effective conservation and restoration work starts with in-depth research to establish the composition and condition of the artefact. Microscopy is an important tool in this research, with different instruments - from stereo to electron microscopes - providing access for different specialist investigations.

The optics used in museums are dictated by the objects being examined. Often these pieces are too unwieldy to be placed under traditional microscopes, and often they are too delicate.

Stereo and Zoom Microscopes

Ideal for First Examinations, Cleaning and Restoration
Whether analyzing a painting or the surface of an historical artefact, your initial examination will benefit from the different illuminations offered by stereo and zoom microscopes. Both microscopes allow objects to be studied at a long distance, and with good depth of field to enable observation of fine details in three dimensions at lower magnifications. Variable zoom positions help pick up individual fibers in

textiles, while also allowing the close study of brushstrokes, craquelure, layering and signatures in paintings. Tiny mineral deposits on ancient coins and other metal objects become visible, informing your conclusions about age and origin. Stereo microscopes, with their flexible arms and boom stands, give conservators the maneuverability they need to handle even very large objects in situ.

With boom stands you can examine even large objects directly at their place.
Chatham emerald, hydrothermally grown in lab, acquired with ZEISS Stemi 508, transmitted light, polarization contrast
The zoom microscope Axio Zoom.V16 delivers both high resolution and a zoom range of 16x.
Saphire ring, acquired with ZEISS Stemi 508

ZEISS Stereo and Zoom Microscopes

Light Microscopes

Varied contrasts for revealing fine details and colors
Light microscopes, with their sophisticated variable contrasting functions, bring state-of-the art capabilities to your workplace. Sensitive, non-invasive and virtually contact-free, these instruments produce highly accurate representations of the structures being examined, along with all the data you need to produce authoritative reports.

Being able to identify different fibers is important for the detailed analysis of textiles, paintings, upholstered furniture and other kinds of museum objects, with applications too for archaeology and forensics. Fibers have usually aged and are sometimes fragmentary or decayed, charred or fossilized. Careful, contact-free investigation is crucial for basic authentication, for assessing damage and identifying its causes, and for decisions on further treatment.

 

The Herzog test, using a polarization light microscope, is helpful for distinguishing natural and synthetic fibers, enabling more informed conclusions to be drawn about origin, age and methods of production. Pigment analysis provides information on the particular colors used to make a painting, and on which ones should be used in its restoration. Details become apparent about which paint layers are original and which have been added by previous restorers.

Polarization light microscopes are equally adept at determining the nature of rocks and minerals. A sample mounted on a thin section slide can reveal vital clues about a rock’s composition, how it was formed and its geological origins. And combined with the Michel-Lévy Table of Birefringence, polarized light microscopes can even help you recognize unknown materials, relating in graphic form the thickness, retardation and birefringence of colored, colorless or transparent substances that defy identification with the naked eye.

Bar olivine chondrule in the Coolidge meteorite in polarized reflected-light. Courtesy of Dr J. Zipfel, Department of Meteorite Research, Senckenberg Research Museum, Frankfurt/Main, Germany
To distinguish between natural and synthetic fibers, polarization microscopes can help.
Structure of the surface of a furniture wood acquired with Axio Imager in darkfield.
Complex multiphase mixture of sandstones by crossed polar light microscopy.

ZEISS Light Microscopes

X-ray Microscopes

3D models that let you look beneath the surface
X-ray microscopy is a powerful tool for geological and paleontological research, taxonomy and general collections research. It enables the interior of artefacts to be examined non-invasively – and also in three dimensions. A model of the object’s external and internal features is produced taking 3D images from different angles as it is rotated. These can then be manipulated and measured on a screen, providing important data on physical dimension, density, porosity and a host of other parameters. 

The 3D model enables conservators to look beneath the surface of things, using different attenuation values to distinguish between materials that look similar under visible light. Fragile items – animal specimens, for instance – can be examined without the need for invasive sample preparation or sectioning, and internal structures can be visualized without removal from their host.

Bear jaw (120 mm X 200 mm) imaged from full jaw to micron-scale view of jaw-tooth interface.
Head of a juvenile great white shark acquired with ZEISS Xradia Versa, Courtesy of M. Riccio, Co-Director, Cornell Imaging Facility, Biotechnology Resource Center, Cornell University.

ZEISS X-ray Microscopes

Electron Microscopes

High magnifications for resolving very fine structural details
A scanning electron microscope (SEM) generates a beam of electrons to create an image of the specimen being examined. It enables the study and analysis of structural details down to micro- or even nanometer scales. Electron microscopes deliver higher magnifications and have a greater resolving power than light microscopes, allowing smaller objects to be observed in very fine detail. 

Used with an EDX detector, it can help you identify the elemental composition of paintings. Powerful field emission SEMs, meanwhile, can resolve details on coated samples as small as two nanometers. And environmental SEMs enable the study of samples without water-removal or sputter coating - especially useful in a museum setting.

Arms with suckers of Eledone sp.-larva, critical point dried, gold-coated, SE2 image.
Fungal spores acquired with ZEISS EVO.
Melosira: Diatoms. Species Melosira arenaria, acquires with ZEISS EVO.
Pollen on textile acquired with ZEISS Evo.

ZEISS Electron Microscopes