Gilding a Naderman Harp

Gilding a Naderman Harp

by Valeria Martin

In December 2008, an 18th century harp built by harp maker Jean-Henri Naderman was brought to my studio for gold restoration.

The Naderman had come from its long-time home, a convent, and was purchased at an auction in Freeport, Illinois by Peter Reis of Harps Unlimited, who sent it to Pat Dougal’s PRD Harp Services in Joliet, Illinois, as it was badly in need of a transformation. It was an honor for me to participate in the restoration of this splendid harp. This was my first introduction to a Naderman. I learned Naderman was born in 1735 in Frebourg, Switzerland. In 1778, he was appointed harp maker to Marie Antoinette, Queen of France. Marie Antoinette’s love of music and playing the harp made it popular and fashionable. By 1784, there were as many as fifty-eight harp teachers in Paris!

The Assessment

The Naderman harp was a beauty in ebony and gold with its richly carved gilded ornament, though the gold’s sealed finish had dulled and darkened from many years of soiling and age.

The neck and column were one continuous piece crowned in the front with a prominent volute decorated with carved acanthus foliage resembling the spiral of a ram’s horn. Tucked beneath the front of the “ram’s horn” a vase brimmed with flowers and fruit. Leaves and tiny berries traveled downward from the centers of the volute.


The column itself was slender, encircled with foliage on the bottom. The baseboard was actually two pieces instead of one solid piece.  The column rested between the two pieces which were decorated with leaves that fanned from the center. Beneath the baseboard, the harp’s base was a simple fluted pattern decorated with a single simple flower in its center.

The harp’s action was housed in the neck and covered with a decorated removable panel. Hand-painted chinoiserie decorated the panel, as well as the other side of the neck and the ebony soundboard on the body of the harp.

The panel and the side of the neck where the tuning pins held the harp strings had gilded low-relief carving. Two gilded coves trimmed the top of the shapely curve of the neck and a gilded low-relief carving of ferns and tiny flowers decorated the knee block.

The Plan

My intention was to bring new life to the Naderman with a combination of water gilding and oil gilding. Water gilding is the art of applying genuine gold leaf to a meticulously prepared surface. Leaves of gold leaf are applied with water-based adhesive and areas are highlighted by burnishing them to a brilliant reflective luster, the hallmark of this beautiful art. Oil gilding is a simpler process of applying gold leaf onto a surface coated with an oil adhesive. The result is a luminous matte finish, but cannot be burnished. This was my plan for restoring the Naderman:

  •  The acanthus ornament on the volute would receive the brilliant luster of burnished water gilding while the low areas would be oil gilded.
  •  The vase of flowers and fruit would receive a combination of burnish and matte water gilding. The leaves and berries would receive the same treatment.
  •  The foliage on the column bottom and the baseboard parts would also receive burnished water gilding.
  •  The flutes on the base front would be matte water gilded with the simple flower in the center burnished.
  •  And lastly, the low relief carvings, coves and any other areas would be oil gilded.

The Beginning (Some of the following photos show work done on various harps)

Commencing work on the harp, the first step was removing the old gilding. I began the stripping by thoroughly sanding all carved ornament down to the raw wood.

The steps performed in the water gilding process are numerous; however the process is defined by three major components:

  •  gesso
  •  bole (also called burnishing clay)
  •  gold leaf


I begin the water gilding process by making the gesso. Gesso is the foundation of gilding. It is made with two ingredients: rabbit skin glue, a very strong natural adhesive and whiting, a fine white powder made from calcium carbonate.

I put a measured amount of rabbit skin glue granules in a container of distilled water to soak for several hours.  I set the container in a pan of heated water to gently melt the swollen granules into liquid. Care must be taken to avoid overheating the glue for this can destroy the glue’s adhesive quality. The container is removed from the heat and the whiting is slowly added to the glue though a sifter. The glue and whiting are slowly stirred until both ingredients are thoroughly combined and then refined by pouring through a strainer. The gesso is ready to apply on the wood. Before applying the gesso, warm rabbit skin glue is applied to the harp’s bare wood and allowed to cure overnight. This creates a strong bond between the wood and the gilding. It is so strong that removing gesso can be a lengthy process. I brush warm liquid gesso onto the ornament layer by layer. When the gesso cools it solidifies. The gesso is sanded, carefully working the sandpaper over all the ornament to make a smooth, flawless surface. The gesso is ready for the application of bole.

Example of gesso on a Wurlitzer column (left) and on a Venus Aquilan.

The Bole

Bole, translated from Greek meaning “a ball of earth”, is a clay-like substance which is applied onto the gesso. It serves as a substrate for the gold leaf. It’s also called burnishing clay because it provides the burnish for the ornament--the areas that have the bright, reflective luster. Bole comes in a variety of colors such as red, yellow, grey, black, blue, and usually purchased as a premixed paste. I mix yellow bole paste with gelatin glue and distilled water in a small container set in a pan of heated water. Several layers of the yellow bole are brushed on as a base coat over all the ornament allowing each layer to dry before the next layer is applied. Next, I mix red bole and cover the yellow bole with several layers. Carefully and slowly the bole is brushed over the intricate details. A smooth and flawless application is a must because any flaw on the surface of the bole will show in the gold leaf. After the bole has completely dried, with a rough cloth I hand buff the areas that will receive the burnishing to a smooth, high gloss.

Example of early Lyon & Healy column with yellow bole

Example of red bole on Wurlitzer column

Now the harp is ready for the gold leaf. 

The Gold Leaf

Gold leaf is gold beaten into delicate, translucent leaves, so delicate that when picked up with your fingers, it will simply dissipate. Hold it in the light, you can almost see through it. American artist Charles Prendergast described gold leaf as “…like a half solidified piece of sunlight”. Gold was originally beaten by hand by skilled craftsmen undergoing a three step beating process. Gold can be beaten as thin as 1/250,000th inch. Today, gold is beaten in a two-step process with automated hammers.




Etching of beating gold to make gold leaf

Gold leaf comes in 3 3/8”x 3 3/8” square sheets packaged in a tissue paper book. A book contains 25 leaves slipped between rouged tissue pages. A box of gold contains 20 books--a total of 500 leaves.

To apply gold leaf onto the bole, I drop a leaf of gold onto a gilder’s cushion, a pad covered with suede leather. I blow the gold with a quick gentle puff to flatten the sheet. With a special gilder’s knife the gold is cut to the needed size. I wet the surface of the bole with a water-based adhesive called “gilder’s liquor” made with distilled water and denatured alcohol with a tiny drop of gelatin glue. Gilder’s liquor activates the glue in the bole to make the gold adhere. To move the fragile gold from the cushion to the bole, I use a special wide flat brush called a gilder’s tip.



Gilder’s tools: gilder’s cushion, gilder’s knife,
and gilder’s tip

The tip is brushed against my cheek or through the hair to generate static. When the tip touches the gold, it adheres to the tip’s hairs and I lay the gold onto the wet bole. The gold leaf is laid piece by piece until the entire area I want to gild on the harp is covered.

An early Lyon&Healy harp receiving gold

 The gold is ready for burnish after at least an hour.

The Moment of Truth

The moment of truth appears when I begin burnishing the gold. I use a burnisher, a tool tipped with a polished agate stone to burnish the gold. With the agate burnisher, I gently press it back and forth over the gold. This is not polishing the gold as many people would believe. What’s actually happening is I’m pressing the gold against the smooth, buffed surface of the bole underneath, a slow process. I press the burnisher over the Naderman’s ornament concentrating on one small section at a time, and the brilliant, reflective luster appears. A good burnish feels like the gold is burnishing itself. It’s like capturing lightning in a bottle! When the burnishing is complete, I apply another layer of gold leaf on top of the burnished gold and burnish it again. The result is a deeper, clearer brilliance. Lastly, I oil gild the low areas on the volute, the low-relief designs, and the cove details on the neck.

Using an agate burnisher to burnish on an early Lyon&Healy harp

The Naderman’s volute and vase after regilding

The Final Steps

When the gilding is complete, the final step is sealing the gold. The water gilding is sealed with lacquer and oil gilding sealed with shellac.

After I had done that, Pat cleaned and repaired the action and other mechanisms, and the Naderman was reassembled and restrung.

A new soundboard with chinoiserie reproduced by a talented artist replaced the original one, which Pat mounted and framed for the new owners.

(Chinoiserie photos courtesy of Patrick Dougal

Here is the completed Naderman harp:

I had the opportunity to meet the new owners of the Naderman when I accompanied Pat on the delivery of the harp. They were a husband and wife whose home displayed their passion for Oriental antiques. The Naderman with its chinoiserie would definitely be a fit!

Reflecting on this experience, I think that the Naderman harp is my “Crown Jewel”. I never imagined becoming a gilder, let alone having a harp as beautiful as this come into my life. Gilding an instrument with such beautiful, intricate detail challenges my skill as a gilder. I don’t work the gilding: gilding works me. The challenge of gilding has made my inner world expand and embrace new possibilities. I hope another one comes my way.

[After completing the article, Valeria wrote, “I’m about to start a new harp project! I will be regilding a 1929 Lyon & Healy Style 26. The harp came to Chicago and Pat disassembled the harp. The parts are in my studio and ready for restoration. I’m excited!]

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