Saturday, February 25, 2012

An American Couple’s Perspective on French Wine and Plaster Traditions: Varietals

The French are renowned and appreciated the world over for their many traditions and a unique perspective on life that form the foundation of their culture and have contributed to our culture here in America. Who doesn’t love a French press coffee complimented with a buttery croissant on a lazy Saturday morning? A visit to the Metropolitan Museum of Art to see the impressionist works of Monet and Cézanne? Although we as Americans enjoy our own hustle and bustle way of life, I think we appreciate the fact that someone on the other side of the pond has taken a little more time to perfect a few of the finer things and are willing to share. Vive la différence!

Two of those traditions mean a lot to my family personally and professionally: Wine and Plaster. My wife Angela is a professional chef trained in classical French cuisine and a wine consultant specialized in wine and food pairing. I am a plasterer who has made numerous visits to France to improve my skills in moulding and ornament. Angela and I talk a lot about our respective interests and have perceived a philosophical constant, a sophisticated approach to product development that these completely different industries appear to share. We got excited about the opportunity to do a project together comparing the common themes we see and sharing them with others.

This blog post is the first of a five part series on French traditions of wine and plaster making framed in a very wine oriented vocabulary:
  • Varietals
  • Terroir
  • Viticulture
  • Viniculture
  • Pairing
Varietals in Wine

As you may know, a varietal is a wine made from a single grape variety. Varietals are very popular in the United States, especially where we live in California. I think we like the simplicity of having a wine from a single grape variety that we can learn about and expect to have certain characteristics. By contrast the French generally prefer wines that are blends. For example, the prized and often very pricey Châteauneuf-du-Pape may contain up to eighteen distinct grape varieties!

Throughout our wine and plaster comparison we are going to concentrate on the popular and much simpler Bordeaux blend. A Bordeaux blend can have up to six grape varieties. Typically though, the following three grapes dominate most Bordeaux wines: Cabernet Sauvignon, Merlot & Cabernet Franc. Interestingly, in the United States we grow and blend these grapes in a similar way. More about that later! For now let’s take a closer look with Angela at a couple of the varietals that she and I love to drink, Cabernet Sauvignon & Merlot.

Native to Bordeaux, the Cabernet Sauvignon grape is the love child of the Cabernet Franc and Sauvignon Blanc grapes. You can recognize the Cabernet Sauvignon grapes because they are quite small, their skins are very thick and are dark blue in color. They cling to each other in very tight clusters and bond tightly to the vine with their strong stems. Many of these physical characteristics express themselves by producing a powerful, complex and masculine wine. The skins, large seeds and stems give the Cabernet Sauvignon wine a dark, almost inky color and strong tannins which can be overwhelming in a young wine, but mellow beautifully with age. With regard to aroma and taste, the flavor profile will vary greatly depending on where the grapes are grown. In new world production, cabernet sauvignon is typified by bold, jammy mouth-filling flavor. Up front you may taste over-ripe blackberries and plums or dried currants gently blended with notes of chocolate or coffee. By contrast, old world productions, particularly French, are lower in alcohol and much less fruit-forward. As a result, earthier and more complex notes of mushroom, leather and tobacco are given their chance to shine.

Merlot, sometimes called “cabernet without the pain” is a perfect foil for its partner. Where Cabernet Sauvignon is bold, powerful and angular, Merlot is round, soft and voluptuous. Merlot grapes are larger than cabernet sauvignon and their skins thinner and almost violet in color. These characteristics produce medium-bodied wine with lower tannins. Although, Merlot is an integral part of the orchestra that is Bordeaux wine, it does quite well on its own with a remarkable range of aromas. In the new world merlot shows notes of plump and perfectly ripened dark-skinned fruit while old world merlot displays deep notes of vanilla or coffee beans and earthy aromas of damp grass and leaves. 
Varietals in Plaster

Plaster has its varietals as well. Whereas varietals with wines start with a single grape variety, varietals in plaster begin with a single mineral. A few of the popular minerals that historically have been used to make plaster are: gypsum, clay, limestone, marl and silica. Paralleling our tastes in wine, plasters made from a single mineral are very popular in the United States. We generally manufacture and use clay, lime and gypsum plasters mixed only with sand. I think the American approach to plaster manufacture resembles our wine production. We like the simplicity of having a plaster from a single mineral that we can completely understand and expect to have certain characteristics. It probably comes as no surprise that the French have a long history of developing plasters that are blends of many minerals.

During our wine and plaster comparison we are going to examine parallels with the aforementioned Bordeaux blend with a historic French plaster blend, Terre de Séléné. As with our Bordeaux blend three minerals dominate this plaster blend: gypsum, limestone and clay. In the United States we have deposits of these minerals and mine them aplenty. Now it’s my turn to take a closer look at a couple of these minerals.
Pure limestone is a carbonate of calcium or calcite having the chemical formula CaCO3. Lime is the main component of many materials familiar from everyday life: teeth and bones, chalk and marble are common examples. It is this type of limestone that is used to make the lime for Terre de Séléné. Plasters made exclusively from pure limestone always have certain characteristics. For example, lime is a very white, reflective material which makes it a great base for creating colored plasters. Lime is highly alkali and inhibits mold growth. Lime plasters such as Venetian plaster, Tadelakt and marmorino are very popular in the United States.

Gypsum and limestone are geologically related. Whereas limestone is a carbonate, gypsum is a sulphate of calcium having the chemical formula CaSO4. Like its cousin, pure gypsum is a very white, reflective material that is easily tinted with mineral colorants. At the same time it has some properties that are unique. Gypsum plaster can be manufactured at a very low temperature (and corresponding low environmental impact), starting at about 150 °C or 300 °F. It also has a fast set with no shrinkage which makes it very useful for moulding and casting. 

As with all grapes, including our Bordeaux varietals Cabernet Sauvignon and Merlot, geology makes a considerable contribution to the qualities of a wine. Geology makes an even bigger impact in the world of limestone and gypsum. Next blog it’s time to go full French and talk Terroir!

This article was coauthored by Angela and Patrick Webb

Sunday, February 19, 2012

Stuc Pierre

Courtesy of Plâtres Vieujot
French Stuc Pierre is a rendered or cast technique for imitation of Ashlar stone derived from a mix of gypsum plaster, hydrated lime (optional) and pulverized aggregate of the original stone to be imitated.


House of Sallust
circa 100  B.C.E.
Although there exist examples of the imitation of stone with stucco among several ancient civilizations, it would be the Greeks and Romans who would perfect the art. The Greeks developed stucco techniques to directly emulate their monumental stone architecture. By contrast, Romans would display a more cavalier interpretation in defiance of Greek norms. Romans manifested a preference for its use in interior ornament and would take advantage of the freedom of the physical constraints stucco afforded by creating purely decorative realizations not possible in actual stone.

In medieval Europe the art of Stuc Pierre was to diminish, if not entirely disappear, transcended by the imitation of stone with distemper and limewash paint techniques. During the Italian Renaissance a resurgence began of the imitation of stone with lime stucco, a notable example being the 16th century Palazzo del Te outside Mantua where cornices, columns, pediments and a variety of ornament were developed to perfection in homage of the prestigious Roman travertine palaces of antiquity.

Palazzo del Te

Courtesy of Plâtres Vieujot
France would soon follow in the 17th and 18th centuries. Stuc Pierre based on gypsum plaster would predominate in 19th century private and public interiors adorning common areas such as entries, halls and stairwells. Not only did it create the illusion of classical stone monumental architecture but provided a comparable durability that has allowed many original installations to be enjoyed until the present time.

Courtesy of Plâtres Vieujot
Due to widespread availability of gypsum throughout France, Stuc Pierre was in common use in regions diverse as the Normandy coast, Provence, Burgundy, the Pyrénées and Côte d'Azur. Particularly in Paris and the Île-de-France it is not uncommon to see extant examples of façades rendered entirely in Stuc Pierre or in combination with Stuc Brique, a similar technique where pulverized stone aggregates are replaced with brick powder. Stuc Pierre was traditionally rendered over a brick or masonry support. With the advent of iron and steel construction at the beginning of the 20th century, Stuc Pierre would increasingly be used over lath to preserve the appearance of a classical architectural façade.

Mise en Œuvre

The first step is the precise selection of the mix. For restoration works a counter type of the original limestone or mortar is engineered. New construction allows for a great artistic liberty. Unlike lime or cement, gypsum is a self binding material. Aggregates such as crushed stone, brick or sand are not necessary for performance of the coating but are added for decorative effect or to lower the total embodied energy. Similarly materials as diverse as wood chips, glass beads, sea shells or linen fibers can be added for artistic expression.

As with any rendered coating, the cleanliness and stability of the support are very important. When used in exterior several principles associated with classical architectural design are to be respected. Eaves, entablatures and stringcourses are important features in shedding water from the façade and preventing localized streaming. Horizontal and backsplash surfaces commonly occurring at gables, window and door openings should be properly flashed. A water table such as a dense, impermeable stone at the foundation prevents water rise due to capillary action. Adherence to a few, simple, well documented precautions results in a beautiful work that endures generations.

Mixing can be done by hand, drill or machine. Application in exterior can be made in a single or successive coats for a total minimum thickness of 1 ¼”. In interior reduced thicknesses of ½” to ¾” are possible over masonry and lath supports or over drywall substrates as a veneer. In all cases traditional stucco and plaster tools can be used including hawk and trowel, floats, darbies, corner tools etc. Various mix designs are available for render, veneer, run in place, mouldings and ornament. 

The finishing of Stuc Pierre is where the skilled artisan is relied upon to unlock the great artistic potential of the material. A French steel razor or Berthelet is traditionally used to shave and level the surface, exposing the beautiful aggregates contained therein. Further treatments such as washing, brushing, burnishing or sanding can be successively used to achieve desired effects. For the cutting of joints a traditional railroad tool or Chemin de Fer is used. Joints can be left open in an Ashlar pattern or refilled with uncolored material to give a mortar effect.


Courtesy of Wright Architects
Stuc Pierre is increasingly being valued in the sustainability market. In the EU, Stuc Pierre is commonly used in straw bale and hemp lime construction. Gypsum plaster has a relatively low energy of manufacture, produced by heating raw gypsum to about 300°F. Additions of clay binders, hemp fibres and reclaimed or recycled aggregates can reduce the embodied energy even further. Traditionally a small percentage of hydrated lime is contained in the mix contributing an alkalinity and natural mould resistance. All of the materials utilized in Stuc Pierre are mineral or renewable, non-toxic and free of VOC’s. Furthermore the porosity of the coating ensures a breathable assembly that takes full advantage of latent heat transfer and reduces thermal bridging.


I would like to thank Joël Puisais, Les Compagnons du Devoir and my colleague Marc Potin at Plâtres Vieujot for the historical references for this posting. Plâtres Vieujot was founded in 1880 and remains the sole privately held gypsum plaster manufacturer in France. More information can be found on our website:

Contributed by Patrick Webb