Shining light on the hidden beauty of micromosaics
Guest Authors: Julia Brand (former V&A Laser Research Fellow) and Carmen Vida (former V&A Sculpture, Ceramics and Glass Team Conservator)
Detail of The Beautiful Sky of Italy by Michelangelo Barberi, 1845, Rome, Italy. Museum no. Loan:Gilbert.894-2008 © The Rosalinde and Arthur Gilbert Collection on loan to the Victoria and Albert Museum, London
As the Gilbert Collection’s galleries prepare to reopen in 2026, a collaboration between the Sculpture, Ceramics and Glass conservation team and the Science team trialled innovative ways to clean some of the most intricate micromosaics. Micromosaics are beautiful artworks made from thousands of tiny glass rods (filati), set onto a rigid support (cassina) with a soft putty, embedded with a tinted wax grouting, and finally polished with an organic coating on top. Over time, the coating yellows and picks up dirt, dulling the sparkle that makes them so special. The challenge? Both the putty and the grouting are extremely sensitive to most solvents, and mechanical action on the glass rods can lead to losses, so traditional cleaning methods can do more harm than good.
Left: Bonbonniere with a broken corner, unknown maker, ca. 1860, Rome, Italy. Museum no. Loan:Gilbert.924-2008. Right: close-up on the fragment showing the different materials
That’s where the laser comes in. We began experimenting with an Er:YAG laser, a type of mid-infrared laser that interacts gently with organic coatings. Instead of scrubbing or soaking the surface, using laser pulses can disrupt the degraded coating and dirt, making it easier to remove without disturbing the underlying glass or grout. It gives us more control, and it cuts down the amount of solvent needed, which is better for the object, for us, and for the planet too.
We had to test this carefully. We started with a damaged bonbonniere (shown above) that is no longer suitable for display. After a lot of parameter tweaking, we found a sweet spot: low fluences of laser energy to loosen the top layer, followed by small amounts of solvent swabbing to lift away the residues.
With that success, we moved on to more objects in the collection, including The Beautiful Sky of Italy tabletop by Michelangelo Barberi (made in 1845). The rectangular glass rods in this spectacular micromosaic are roughly 1×2 mm in size, thousands of them composing a beautifully detailed image that is nearly 1m wide and shows eight views of Italian cities around a centre occupied by cherubs holding the attributes of the arts. Over time the whole surface had darkened and yellowed heavily, especially across its blue sky.
Carmen and Julia working on the tabletop (Museum no. Loan:Gilbert.894-2008)
The most successful cleaning results were obtained by applying the laser and then gently swabbing with a solvent. The use of Evolon® CR textile as a poultice (with the same solvent) further improved efficiency by rapidly lifting some of the yellowed coating. In the end, we were able to remove the yellowed coating and dirt and restore much of the original vibrancy. Seeing the blue tones gradually reappear as cleaning progressed was one of the most rewarding moments of the project.
Left: Carmen and Julia working on the tabletop (Museum no. Loan:Gilbert.894-2008); Right: before and after cleaning, showing removal of dirt and yellowed coating
Examination using a high-magnification Hirox microscope showed that the glass rods and grouting weren’t affected by the laser, and that the treatment was effective at removing dirt from the surface.
Left: Julia doing microscopy on the tabletop (Museum no. Loan:Gilbert.894-2008) with a Hirox microscope; Right: close-up of the surface before and after cleaning, showing clean and undamaged materials (right; picture adapted from our publication, see link below).
Every object is a little different, and not all micromosaics responded in the same way, so the cleaning had to be adapted to each piece and tested before going ahead.
The Gilbert Collection is reopening in 2026, and we cannot wait for visitors to see these pieces looking their best!
This research was partially funded by Ed and Anne Teppo, who donated the Er:YAG laser used in this project and funded Julia Brand’s research fellowship. The V&A also acknowledges the UKRI Arts and Humanities Research Council (reference AH/V012134/1) for funding the refurbishment of the V&A Science Laboratory, including the purchase of the Hirox HRX-01 digital microscope and Hitachi TM4000Plus Desktop SEM used for the digital microscopy and scanning electron microscopy in this study.
The full details of this study can be found in our open access publication.
