Architectural Gilding At Sea

The Traditional Way

Superyacht, a term often used now for a commercially operated luxury yacht where one may find marble floors, spiral staircases - or, if you prefer - an elevator. And in this case, 900 feet of 23kt traditionally water gilded moulding.  

2013 saw the completion of Invictus, a year after I was contracted to gild the interior of the Executive Office on the top floor of this magnificent 850 foot-long ship.

When I first met with the shipbuilder and the Design team, we reviewed the plans for gilded mouldings that would later be fitted into routed grooves (see photo below) along with cove and floorboard mouldings that would combine gilding and black catalyzed varnish. 

The Plan

The presentation of various samples of gold leaf gilded mouldings resulted in a choice for water gilding due to its elegance and ability to balance the requirements of a hint of brilliancy against an aged appearance with a rubbed leaf over a dark, earth-red ground. The hermetically sealed design of the ship, of which I was informed is better than one's home, would provide a suitable environment for the water gilded gesso.

The final design plan was to use water gilded 23kt gold leaf, burnished over a custom-mixed dark red bole consisting of 50/50 German Red and Black clay. The leaf would be rubbed to expose the dark red bole and then toned with an umber-tinted Ruby shellac.

As for challenges, there are always difficulties with a large scale project that need to be confronted and resolved. In this case one of the larger issues was that the mouldings to be fitted into the wall panelings measured only a quarter inch wide and were joined at the mitres like picture frames so the mitre cuts wouldn't show. Unfortunately, once hydrated, the frames bowed in the middle causing some of the corners to pop open - I would sometimes actually hear them snap from across the room! - so the handling of these delicate mouldings proved very difficult, especially during burnishing. As the wall panelings were already meticulously painted the gilding needed to be done separately and the mouldings inserted. 

Applying weights on the corners of the frames after any hydrating helped stabilize them and after many hours all the various sized frames were finally gilded, toned, and installed successfully.

Going With The Flow

One of the aesthetic challenges was that some of the gilding was accomplished in the studio, some onsite in the manufacturers's workspace - the size of a small airplane hangar - and also onsite on the yacht itself in a separate hangar amongst the wiring, cables, woodworking, and painting of the yacht builders. The goal was to maintain a consistent antique color tone on all 900 feet of gilded moulding, executed under three separate lighting conditions while also envisioning how the appearance may change once the ship was launched where the lighting would change once again under natural conditions. The only true approach to this is to maintain awareness, make sure the toning recipe and application is consistent, and to not go too dark on the tone - it's always easier to make something a bit darker later than lighter.

In the end, the look of the water gilded gold leaf set against the deep, dark black elegance of the varnished walls and cabinetry was quite stunning. Several studio assistants were on hand to contribute their skills throughout this year long project: Madeline, Heather, Alyssa, and with a special thank you to Swedish Gilder, Restorer, and friend Malin Isaksson!

For those interested in studying gilding for use in architectural interiors Charles Douglas Gilding Studio offers both In-Person and Online classes. Visit the website page Gilding Class Information for more detail or go to the Book A Gilding Class page for an up-to-date class schedule and Registration.

Double Gilding

An object that is double gilded has two layers of gold leaf laid, one atop of the other. This is normally done with the traditional water gilding method and imparts a very deep, golden tone that is generally free from defects in the gilding. Water gilded leaf has a satin tone in its natural state; burnishing the gold or silver leaf brings the metal to a brilliant lustre.

When water gilded leaf is left satin, it's left un-burnished. This means that the leaf not only has a satin tone but is also not compressed into the clay bole that is applied to the underlying gesso such as a gilded picture frame furniture, or other wooden object and therefore bonding of the gold leaf to the surface is somewhat more vulnerable to wear. It has historically always been this way and old water gilded frames and furniture that have unburnished satin areas will likely show more wear than their burnished counterparts. Therefore, I often use additional 10@ RSG (rabbit skin glue) or gelatin in the gilding water for unburnished areas to aid in adhesion. I also sometimes sometimes apply a 5:1 10% Glue to Water wash over the satin leaf for added protection.

Spot and Single Gilding

Single layer water gilding sometimes results in some anomalies ('spots' exposing underlying clay bole from trapped air bubbles or breaks in the leaf) during the process of gilding, many of which can be covered during spot gilding, although if done excessively the result can be somewhat unsightly due to ghost images of these small sections of leaf applied over existing gilded leaf. Double gilding covers all the anomalies that single gilding sometimes leaves behind and is useful when gilding satin areas. It offers a very solid layer of gold leaf.

There are times, though, that the somewhat translucent quality of single water gilding is preferred when developing a satin section, especially when other areas of the water gilded object are rubbed, abraded, or distressed. As an example, a picture frame that is antiqued to some degree can be a little jarring if the sides are a strong solid double gild. It is often aesthetically best if the overall appearance of the gilding presents a sympathetic quality between each of the gilded sections, where no one area is dramatically different in its condition.

The technique of Double Gilding is demonstrated in the Water Gilding for Panels Online gilding class which is discussed on the website page for Gilding Class Information.

What Exactly Is Gilding?

To many of the uninitiated, intrigued by the beauty of gold leaf, one of the first questions I hear concerning gilding is “what makes it stick?”. It’s actually a long answer, depending on the method of gilding, historical reference, and personal choice.

Gilding, which is the application of a metal leaf to another surface is comprised of three main methods: Water Gilding, Mordant Gilding, and Glass Gilding/Verre Églomisé. Water Gilding is used primarily on wood although can also be performed on plaster, hydrocal, and a mould-making material known in the Framing and Furniture world as Compo. Mordant Gilding which includes such adhesive agents as oil size and acrylic emulsion is designed for any non-porous surface from sealed wood and glass to stone and walls. Glass Gilding can be performed on either the front or the back of glass, from mirrors and tabletops to decorative glass sculptures and gilded and painted sceneries of age-worn Grandfather Clocks.

Within these methods lie the techniques used for Byzantine, Russian, and Greek Iconography, Manuscript Illumination, 13th-18th c Florentine gilded panel paintings; the gilded architecture of Cathedrals and Domes and Palaces; the ornate picture frames of French, Italian, Flemish, and early American design; Asian temple woodcarvings, Tibetan metal work; the decorative effects of raised gesso for calligraphy or its use on frames and furniture in the form of pastiglia; the beauty of egg tempera paint over water gilded gold leaf and etched away in a method known as sgraffito; and the gesso treatments of granito. The uses of gilding throughout the centuries seems endless.

Water Gilding

Traditional water gilding generally involves rabbit skin glue and/or gelatin; glass gilding/verre églomisé uses a food grade gelatin for bright gilding or oil size for contrasting matt sections although glair - beaten egg white - can also be used as described by Ceninni in his 15th c Treatise Il libro dell’Arte for religious reliquaries which also leans matt, depending upon the strength. Oil size is a popular bonding medium in mordant gilding alongside other mordants including garlic, gum ammoniac, and contemporary acrylic emulsions. The use of these mordants extend from oil gilded interior and exterior architecture to the application of glair and gum ammoniac for manuscript illumination and bookedge gilding.

Each of these bonding mediums carry their own characteristics and purpose of use. Referred to as Size, many mordants such as oil size and acrylic emulsion (sold as water-based adhesive) are applied topically to a non-porous surface and allowed to dry to a slight tack on which the gold, silver, or other precious or non-precious metal leaf is applied. Both of these adhesive materials are considered mordant gilding. While we often hear of the popular term oil gilding, there is no separate term other than mordant gilding for gilding with acrylic emulsion and despite it being water-based it would be incorrect to refer to it as water gilding, a completely different method of gilding rooted in antiquity dating back over several thousand years.

Traditional water gilding involves a protein binder throughout the process. My method of practice begins with preparing a 10% rabbit skin glue (rsg) solution: 1 part dry granules to 9 parts distilled water. Once the granules soften overnight they are heated in a double boiler until dissolved, the mixture never surpassing 120F to avoid destruction of the enzymes which would affect the adhesive quality of the glue. The wood object to be gilded is then coated with a layer of the heated size and left to dry 24 hours, allowing the wood time to re-stabilize from the hydration.

Rabbit Skin Glue As A Binder

The Rabbit skin glue solution is also used to prepare gilder’s gesso, a combination of 10% rsg, additional water, and calcium carbonate or calcium sulphate which is applied to the sized wood. 10% rsg is also used in the preparation of the clay bole and applied over the gesso. A 10% solution of gelatin can be used for the bole instead of rsg as a matter of preference as it doesn’t require the lengthy soaking time as the rsg granuals.

The term gesso is used to convey foundation or ground. I have recently come to refer to it simply as gilder’s gesso to help differentiate it from other forms of gesso such as oil or acrylic-based. They are all referred to as gesso which can be confusing as the term is shared but the materials that are used in their manufacture are quite different. Although they each form a ground, a painter will use gesso to isolate the canvas from the effects of oil paint while a gilder will apply gesso to wood to fill the grain and in the case of water gilding, to burnish the gold to a high lustre.

During water gilding, the gold leaf is laid over the clay bole once the bole has been sufficiently hydrated with water and alcohol, reactivating the glue in the clay which bonds the leaf to the surface. The leaf is then later burnished to a beautiful brilliancy. Often the gold leaf is left matt in specific sections of the gilded object for contrast to the burnished areas.

Clay bole is obtained as either a dry cone which gilders will then grind or tumble in a ceramic tumbler known as a Ball Mill as I do with water and tumbling stones until creamy or it can be purchased pre-mixed where the clay has already been tumbled and mixed with water. This clay is then combined with a specific amount of dissolved rabbit skin glue or gelatin and applied over the gesso that has been sanded smooth. The clay provides a sympathetic color under the gold or silver leaf and aids in the effectiveness of the burnishing with an agate stone burnisher.

Gilders will often use the terms Clay Bole, Clay, or Bole interchangeably. Intriguingly, this holds true whether the clay bole is in its raw dry cone or pre-mixed state and whether or not it has been combined with the glue size. This is important to note since protein binders such as rabbit skin glue and gelatin have a short shelf life once mixed with water and should never contaminate the raw form of the clay bole which normally sits on the gilder’s shelf as it will turn the container of raw clay rancid and useless. The rabbit skin glue or gelatin should only be used to create what I call prepared bole - the solution of clay, water, and glue which is used while gilding and stored in the refrigerator when not in use.

Protein binders such as rabbit skin glue can last many months in their dry state when stored in a glass container and cabinet but breakdown fairly quickly once combined with water. Depending upon the temperature setting and condition of refrigerators, two weeks is generally a good guideline for maximum life of the prepared glue, whether in the form of the 10% water and glue size, the prepared clay bole, or the gesso. When any of these prepared materials for gilding deteriorate, which could be between 2-4 weeks in the refrigerator, the prepared glue size, clay, or gesso will develop a soft, watery texture and eventually a strong odor if left passed their prime due to the presence of the rsg or gelatin as they are both protein binders and should never be used once deteriorated since the adhesive quality will be greatly diminished.

Mordant Gilding

The method of mordant gilding with either oil size or acrylic emulsion is less time intensive than traditional water gilding although each step is very important to be done correctly to achieve an attractive gild and to avoid any stressful mishaps from wet or pooling size.

Unlike water gilding which requires a porous surface, mordant gilding requires a non-porous surface. Technically, raw wood could simply be given numerous coats of shellac to reduce the porosity on which oil size or acrylic emulsion can then be applied. Once the size dries to a tack the leaf is laid and gently compressed with either a soft pounce pad or light pressure through the thin rouged paper inside the gold leaf booklets or whatever is the gilder’s preferred method for smoothing the leaf. However, although a porous surface can be made non-porous there are other steps a gilder can take to create a more attractive gild than simply gilding over shellac-sealed wood.

I often apply six coats of gilder’s gesso to wood frames and furniture to fill the grain, sand the gesso and apply a Primer and enamel paint as an undercoat before oil gilding, or an acrylic paint as an undercoat for gilding with acrylic-emulsion, providing a nice foundation free of the presence of wood grain while the paint seals the porous gesso and offers an attractive color under the somewhat translucent gold leaf. Other preparatory treatments are often necessary for other surfaces such as metal, especially for exterior work for successful bonding and longevity.

Verre Églomisé

Gilding on glass is a method that I often refer to as Glass Gilding or by the French term Verre Églomisé, named after the 18th c French Dealer and Restorer Jean-Baptiste Glomy (1711-1786) who reintroduced the ancient Roman technique of gilding and painting on the back of glass.

As a weak size made of gelatin dissolved in water is used, some refer to this method as water gilding which I refrain from to avoid confusion with traditional water gilding. The form of gelatin used for glass gilding today comes in the form of a clear, short rectangular sheet with perforated diamond shapes for ease in measuring. Pharmaceutical capsules have also long been used and some gilders prefer these although in either case, the gelatin should be stored in a glass jar in a cool cabinet. Prepared as a water-based mordant it is best to use fresh gelatin as age can affect adhesive quality. A clear, crisp snap of the gelatin ‘diamonds’ is a good indication of fresh quality.

For the beginning gilder it is perfectly good to choose a path of specialization in a particular area of gilding, whether as a water gilder of frames or furniture, a hand-letterer on glass, a manuscript illuminator, or a restorer of gilded antiques. Whether someone chooses to specialize or to become proficient in a variety of methods and techniques it’s beneficial to acquire an overall knowledge of the various forms of gilding, their history and purpose of application. It can be helpful in a business context and in the sense of self as an artist, in one’s confidence, choices, and opportunities that may come along.

For a full listing of classes the full curriculum is currently being added to the Gilding Class Information page. ~

For those interested in studying gilding Charles Douglas Gilding Studio offers both an in-person and Online Classes including studies in Glass Gilding, Verre Églomisé, Mordant Gilding, and Traditional Water Gilding. Visit the website page Gilding Class Information for more detail or go to the Book A Gilding Class page for an up-to-date class schedule and Registration.