Petite Preservation: Conserving Portrait Miniatures

The Blue Gown (Portrait of Ethel Coe),1899. Martha S. Baker (American, 1871-1911). Watercolor on ivory, Diameter - h: 10.00 cm (h: 3 7/8 inches). Diameter of frame - h: 10.80 cm. Gift of Mr. and Mrs. Charles E. Baker 1915-142. Recent discovery of the dramatic painting on the back (left) of this miniature painting on Ivorine, an early plastic substitute for ivory.

One of the finest collections in North America, the Cleveland Museum of Art's miniatures span six centuries, bridge eight European countries as well as America, and number nearly 170 objects. These intimate portraits were exchanged by friends, lovers, and family members as tokens of affection and often commissioned on occasions of departure, marriage, or death. Opening on Sunday, November 10, Disembodied: Portrait Miniatures and Their Contemporary Relatives, curated by CMA Assistant Curator Cory Korkow, reawakens the spirit of these works, which are removed by hundreds of years from the hands into which they were originally placed. 

Exhibited in its entirety for the first time in over half a century, the stunning collection is presented from a fresh perspective and features more than a dozen new acquisitions. For 600 years, miniature painters were deeply engaged with issues of death, likeness, memory, identity, privacy, and body-centered scale. The exhibition includes works by five prominent contemporary artists – Janine Antoni, Luis González Palma, Tony Oursler, Dario Robleto, and Hiroshi Sugimoto – who are also invested in exploring these themes today.  The contemporary works are placed in an unprecedented, intimate dialogue with the portrait miniatures, revealing new relationships and uncovering hidden secrets. 

Paper conservator Moyna Stanton is responsible for the museum’s portrait miniature collection, aided by visits from Cecilia Rönnerstam, Curator and Conservator of Portrait Miniatures at the Nationalmuseum in Stockholm. Rönnerstam recently came to Cleveland from Sweden to perform conservation for the upcoming exhibition. She sat down and talked with us about the challenges and techniques used in preserving these delicate portrait miniatures.

CMA: How did you get into the field of art conservation, specifically for portrait miniatures?

Cecilia Rönnerstam: I have been in the conservation field for about 20 years now. Starting out as a university student in Art History (Gothenburg University, 1992), I soon turned to the field of conservation since my interest in art was from a technical and material point of view. I am now connecting the two in what today is known as ‘technical art history.' I finished my degree in London in 1999 and went back to Sweden in 2000 to work for Nationalmuseum in Stockholm. The Nationalmuseum houses the largest collection of portrait miniatures in the world, with 5,000 works and growing. The collection was originally based on two extensive donations, but today the museum is collecting actively, with new acquisitions coming in every year.  

It's natural to assume that a "portrait miniature" is always pocket-sized, but that's not always the case. What is it about a work of art that actually constitutes it as a “miniature?”

A portrait miniature is not defined by size, but by the technique and materials used. A true portrait miniature is painted in watercolor on vellum (thin animal skin) or on ivory. The important thing is that the painting medium is gum Arabic with watercolor and/or gouache, and the support for the painting is vellum or ivory. This means that a small oil painting is technically not a miniature, while a large painting in gum Arabic on vellum or ivory is a miniature.

L-R: Portrait of a Man, about 1655. Samuel Cooper (British, c. 1608-1672). Oil on vellum, Sight - h: 8.00 w. 6.30 cm (h : 3 1/8 w: 2 7/16 inches). The Edward B. Greene Collection 1941.551. Portrait of a Woman Wearing a Miniature, c. 1780. Thomas Hazlehurst (British, c. 1740-c. 1821). Watercolor on ivory, Overall- h: 7.50 w. 6.00 cm (h:2 15/16 w: 2 5/16 inches). The Jane B. Tripp Charitable Lead Annuity Trust 2012.57.2. Portrait of a Woman, c. 1646. Samuel Cooper (British, c. 1608-1672). Watercolor on vellum with gold border, Sight - h: 7.30 w. 6.10 cm (h :2 13/16 w: 2 3/8 inches). The Edward B. Greene Collection 1940.1204.

How were these miniatures created?

The word miniature can be etymologically traced back to minium, which is Latin for the pigment red lead, used in book illumination. The artists who painted the illuminations in early illuminated books and manuscripts were known to use the characteristic strong red pigment minium, and the pictures were called miniatures. The earliest known portrait miniature to be painted and used separately from an illuminated book tradition dates from around 1525. The art developed in sixteenth-century England with strong connections to France and Germany. Hans Holbein was an excellent painter of portrait miniatures in the 1530’s. Today many of his works can be found at the Yale Center for British Art. 

It was very important to keep the materials and techniques of the book illuminators, therefore all the early miniatures are painted in watercolor on vellum. The vellum, being very thin, was normally stuck to card before painting. This has led to the misconception that early miniatures are painted on card, but the real support is vellum. 

Around 1700, ivory became fashionable as a support for painting miniatures on. The female artist Rosalba Carriera is considered the first to use paint miniatures on ivory. Very soon, all portrait miniatures were painted on ivory, but the paint medium is still the same: gum Arabic, in watercolor and/or gouache. While early miniatures show a rather matte surface, later ones can be so glossy that they are mistaken for oil paintings. As the technique of painting in a water soluble medium on ivory developed, the ivory sheets became thinner and sometimes artists would put a metal foil on the back of the sitters face for example, to make use of the translucency of the thin ivory, reflecting light and making the features ‘glow.'

The tradition of painting portrait miniatures slowly disappeared when photoraphy was invented in the middle of the nineteenth century, but the twentieth century experienced a revival of miniature painting.

So what appears to be a simple miniature is actually comprised of layers -- the frame, glass, ivory or parchment, etc. Can you tell us more about the "behind-the-scenes" of a miniature?

The portrait miniature would normally be painted as described above, in watercolor on vellum or ivory. As it no longer has the protection of being inside a book, the delicate and very easily damaged paint surface needed some other kind of protection, therefore they have cover glass. 

The miniature would be sealed to the cover glass with a thin membrane to avoid dust from disturbing the surface, and the package then fit into a frame. The framing can be a gilt wooden frame but more often a metal locket or bezel, sometimes adorned with jewelry.

Some of these works are hundreds of years of old. What are some of the common conservation issues that need to be addressed before displaying miniatures?

The most problematic issue is that of flaking paint. The various layers of organic composition in the miniature react to changes in relative humidity, and the paint layer may actually start to peel and fall off. Losing the paint is equivalent to losing the portrait itself, so I always start by looking at the paint layer with a microscope before any handling. 

The paint can also fade easily - disappearing due to light exposure. This is not reversible, and unfortunately causes issues when describing and understanding the miniature. Some colors may have been much stronger originally, or have had a different tone.

Another major problem has to do with the glass protecting the miniature. Due to variations in the composition of the glass,it can develop a condition known as glass disease or “weeping glass”. An ion exchange with the air makes salts develop on the glass’ surface, and under certain climatic circumstances the salts absorb water and turn into droplets on the inside of the glass. Of course, having fluid alkaline salt solutions so very close to a water soluble paint layer is not good. If droplets can be seen by the naked eye, the situation is pressing!

What is a typical conservation interventionand some of the tools used to preserve these works?

Typical conservation would include consolidation of flaking paint, using natural or synthetic adhesives/consolidants depending on the nature of the paint layer in question. If there is actual erosion in the paint, we may choose to do inpainting, but ethically this is rather controversial.

There are various treatments for glass disease, but if damage occurs, then the glass must be replaced. If the glass is only cleaned, the climate must be controlled and the glass monitored on a regular basis to prevent further damage.

When it comes to miniatures on ivory, the ivory itself presents a problem as it easily warps and cracks. This can be restored to some degree, but the best method is to try to prevent changes by keeping the miniatures in stable climate conditions.

The most difficult part, however, is often to gain access to the miniatures themselves since the cases/lockets can have been made to never be opened again. It takes much skill and knowledge to open these frames without causing damage, and sometimes I decide not to open them.

Portrait of Lucy Russell, Countess of Bedford, nee Harrington c. 1616. Isaac Oliver (British, c. 1558-1617). Watercolor on card, Unframed- h: 4.90 w. 4.10 cm (h: 1 7/8 w: 1 9/16 inches). The Edward B. Greene Collection 1941.559.

For folks who may have a miniature collection at home, what tips may you give in order to preserve them?

Keep them out of direct sunlight!


Disembodied: Portrait Miniatures and Their Contemporary Relatives is on view at the Cleveland Museum of Art Sunday, November 10, 2013 through Sunday, February 16, 2014. Stay tuned for more behind-the-scenes looks at the making of this exhibition here on the CMA blog! 

> View the collection online
> If You Remember, I'll Remember: A Conversation with Artist Dario Robelto

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