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

In our previous post we familiarized ourselves with the concept of varietals and how they exist in wine and plaster. For wine we learned that each variety of grape possesses unique characteristics and that a few of these grapes varieties actually produce a good wine without blending, known as a varietal.

Varietals are important; however, for the French there is one contributing factor in making a truly great wine or plaster that is absolutely fundamental. That essential component is the one we have little to no control of. It is summed up in a small yet tricky to pronounce word called terroir (ter-whah).

This blog post is the second 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

Terroir in Wine

Terroir comprises all the geologic, atmospheric and climactic conditions found within a wine-making region that give grapes the foundation they need to develop the characteristics we enjoy in our favorite wines. Just like it sounds, terroir is an extensive topic. For our glimpse into this world; however, the following overview addresses three key aspects of terroir: temperature, moisture and soil composition.

All of the world’s major wine growing regions are situated between 30˚ and 50˚ latitude in both the northern and southern hemispheres meaning that cool to moderate temperatures are optimal for wine grape growing. In cooler climates with less sun exposure (think Washington State or Germany) ripe grapes retain enough “greenness” to produce wonderfully crisp, herbaceous wines like sauvignon blanc which pairs nicely with a green salad topped with goat cheese, green beans and basil pesto. In warmer climates (California and Bordeaux) grapes remain on the vine longer sunning themselves and developing more color, sugar and complexity in the process. The resulting big, bold, fruit is why cabernet sauvignon is known as King Cab.

California and Bordeaux are world-class wine producing regions with oceans bordering both regions providing a moderate and stable climate with minimal risk of damaging frosts. Rainfall in both regions averages a healthy 29 to 34 inches annually. In general, when grapes receive less than optimal rainfall, the vines will produce fewer grapes, though often of superior flavor. In contrast, if heavy downpours occur, particularly close to the harvest time, the grapes absorb too much water, which dilutes the flavors and produces low quality wine. So balance in moisture be it rain, fog or dew is crucial to superior grape production. However, while moisture is important for the vineyard, of equal importance is the vineyard’s drainage system. This leads to our third topic of terroir: soil composition.

As a rule the best wines come from grapes that have suffered a bit; where nutrients are available, but the vine must work for them. According to The World Atlas of Wine writers Hugh Johnson and Jancis Robinson state that best soil (for vineyards) is not particularly fertile, it drains quickly thus forcing the roots downward in search of a water supply. Vineyards in the Medoc region of Bordeaux produces some of the most notable wines because beneath the gravelly topsoils are alternating layers of hard compacted sand and clay. These quickly draining surfaces force the roots to dive deeper until they reach a moist layer of sand and clay near the water table. When nutrients are too easily accessible, vines become complacent and results are one dimensional grapes with underdeveloped structure and complexity.

Terroir in Plaster

For plaster, terroir means geology. It is what nature has provided us. You can’t make something from nothing and you can’t produce a great plaster if the geology is poor. Let’s again take a closer look at the terroir of two of the minerals used to make the plaster blend Terre de Séléné: lime and gypsum.

Lime typically is derived from limestone. Limestone is sedimentary rock formed from the skeletal remains of marine creatures that accumulated on the sea floor millions of years in the past. With time and pressure these skeletons are pressed together in beds of stone.

Some limestone contains contaminants of clay or other materials that affect its chemical properties. When these "hydraulic limes" are baked they will readily react and harden when mixed with water. However, many limestone deposits found in both France and the United States are relatively pure with little contamination from clay or other materials. This type of pure limestone produces a lime that blends well with other plasters. It is the very terroir needed for the lime in Terre de Séléné.

I mentioned in the previous post that gypsum and limestone are geologically related. While limestone was forming on ancient sea beds another phenomenon was occurring in salt marsh lagoons along the shore. Through repeated cycles of seawater infiltration and evaporation gypsum, salts and other compounds precipitated and formed large masses.

Many of these masses have been preserved relatively unchanged, covered by layers of clays that protected them from erosion. In these one can find gypsum rock with many of the original impurities that give the gypsum very interesting properties often useful for construction. In many instances though the original gypsum, being more soluble in water than other precipitates, would be carried off with underground water to recrystallize in successively purer forms in subsequent locations. Many distinct forms of gypsum with diverse crystalline, chemical structures and levels of purity formed. There are gypsum crystals found in underground caves in Mexico for instance that measure over 30 feet long and weigh several tons each, the largest crystals in the world! 

Grapes, gypsum and limestone were here a long time before we arrived on the scene. Terroir is the result of millions of years of geology and current climate conditions we study and benefit from but can’t imagine to control. That being said good wines and beautiful plasters don’t make themselves. Next blog we’ll consider the human touch, Viticulture.

This article was coauthored by Angela and Patrick Webb

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

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.

History

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 16^th 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 17^th and 18^th centuries. Stuc Pierre based on gypsum plaster would predominate in 19^th 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 20^th 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.

Sustainability

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.

Conclusion

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: http://www.platre.com/platre/


Contributed by Patrick Webb

Scagliola

The highest expression of the plasterer’s art has been created, lost and rediscovered. Yet for the past two millennia Scagliola has never ceased to fascinate nor witness its aura of mystery diminish.

Part sculpture, part science, the sophisticated process that gives birth to Scagliola demands the focused mind and precision of a chemist, the hands of an experienced plasterer and the subtle, sensitive eye of an artist.

History

Scagliola results from a meticulously programmed sequence of tinting, blending and arranging plasters to imitate marble. Archaeologists have discovered that the Romans and the Egyptians employed methods, long since forgotten, to imitate marble in plaster. However, it was in the 16^th century Italian Renaissance that the contemporary approaches to Scagliola were conceived and perfected to effect complicated inlays in furniture surfaces.

By the early renaissance many desired marbles were rare or had been exhausted. Scagliola could imitate such marbles as well as create colours and patterns that did not exist in nature. The use of Scagliola soon expanded to casting in ornament, column shafts and even entire walls, a process that became known as Stucco Marmo.

The use of Stucco Marmo expanded throughout continental Europe and finally to Britain in the 18^th century. Prominent uses of Stucco Marmo Scagliola in England include column and pilaster shafts at Buckingham Palace and the Syon House by Robert Adam. A significant breakthrough in plaster technology was achieved in the mid 19^th century with the advent of Keen’s cement. Keen’s paved the way for a new method for producing Scagliola called Marezzo, known in the United States as American Scagliola due to its ready acceptance and prominent use from the mid 1800’s until the Great Depression.

There are countless recipes, historical and contemporary, in all cases secret and proprietary for the ingredients and mixing of Scagliola. Let’s attempt to at least partially pull back the curtain of secrecy with a basic explanation of Scagliola manufacture.

Manufacture

Traditional Scagliola can be done in situ (in place) or on a bench. Work performed in situ requires several precautions in preparation of the substrate. In all cases the work environment should be clean, warm and dry.

Finely ground Plaster of Paris is used as the base material. Animal hide glue high in collagen such as rabbit or isinglass is prepared the day of manufacture to retard the plaster and add strength to the work. Dry mineral pigments can be introduced directly into the dough, mixed with dry gypsum, or emulsified depending on desired effect. Optional ingredients include whiting or selenite (ground gypsum) as filler, linseed oil to complement the glue as a retarder and aid in workability, and marble chips for decorative effect.

Much like a bread maker working with flour, yeast and water, the artisan kneads Plaster of Paris and glue water to the consistency of firm dough. This is best accomplished by forming a ring of dry plaster surrounding a central "castle" of plaster. The "moat" is filled with glue water and the process of cutting and kneading begins.

Through a series of slicing, addition of pigments, folding and re-joining the whole of the mass is mixed and set aside as large balls placed in ratios and arrangements that achieve the desired result: a counter-type of true marble or a fanciful creation. Depending on the desired outcome, from the initial mixing colored slurries and other preparations are set aside for decorative effects. Much of the artisanship lies in a process of mental reverse engineering. One must conceive the desired outcome, have all materials on hand and systematically take steps to accomplish the effect.

Typically the plaster is built up to 1/2” to 5/8” thickness, leaving 1/8” for cutting of the surface. Once the material has achieved an initial set it can be planed with an appropriate cutting tool such as a Berthelet or French razor, removing the 1/8” excess to realize a flat surface. At this point the material is still malleable and can be allowed to cure as a flat panel. Alternatively, slices of Scagliola can be pressed into a mould or directly on a keyed plaster substrate in situ. For ornamental work such as balusters, urns and column shafts, the Scagliola can be wrapped around an appropriate base and turned on a lathe.

Once the Scagliola has been allowed to set and dry naturally the work of polishing can commence. Traditionally, after cutting the Scagliola natural pumice stones and damp sponges are used to smooth the work. The final smoothing and polishing historically was achieved with Water of Ayr, a natural snake stone from Scotland renowned principally as a hone for polishing barber straight razors. Modern polishing techniques arrive at a similar result with increasingly fine grit wet/dry sandpaper. The finished surface can be rubbed with linseed oil to increase luster, hardness and add a measure of protection from stains.

The Marezzo or “American Scagliola” technique was a true innovation that followed a distinct methodology. Cutting of the surface is not required as the veining and coloration is done on the face of the mould in a thin layer for ornamental pieces. Flat panel work is typically carried out on thick plate glass so the patterns created can be seen from below.

The Marezzo plaster mix is based on Keen’s cement, a slow-setting gypsum cement that does not necessitate the use of retarders or hardeners. Silk threads are used for veining and dry mineral tints can be used to provide color.

Conclusion

Scagliola has enjoyed a rich history adorning many of Europe’s most prestigious works of architecture from the Renaissance through the Neoclassical periods. Likewise in the United States Marezzo figured prominently in many of our architectural triumphs of the 19^th century and still is to be admired in the grand entrances of court houses, state capitols, railway stations and fine hotels across the country.

This article was coauthored by Patrick Webb and Sloan Houser

Photo by Walter Cipriani

EIFS and Synthetic Stucco

The terms EIFS and synthetic stucco are synonymous to many. Why discuss a synthetic coating in a blog about Real Finishes? EIFS systems have come to occupy a significant percentage of exterior cladding systems specified by design/build professionals in the United States. It is important to understand the contemporary architectural approach in exterior building cladding design utilizing EIFS to effectively articulate how traditional finish systems perform and compare.

It should be noted that synthetic stucco is only the finish component of an External Insulated Finish System or EIFS cladding and can be used in certain other non-EIFS applications. There are some variations in design; nevertheless, EIFS systems typically are comprised of the following components over an acceptable substrate:

1. A vapour/moisture barrier. This traditionally has been a commercial vinyl sheathing or felt paper. Some EIFS manufacturers are now producing a liquid barrier applied like wet paint that performs this function within hours of application.
2. An insulation board typically made of expanded polystyrene. Boards are usually affixed with an acrylic fortified cementitious paste by notched trowel. The lines of the paste are usually vertical to allow water to drain downward should it get behind the foam.
3. Another typically acrylic fortified cementitious paste is applied over the entire surface of the foam and a plastic mesh is embedded to give the coating strength.
4. Finally an integrally colored synthetic stucco is applied in a thin layer as a finish coat.
5. Many EIFS systems include a track running along the bottom with a weep screed (holes) that allow any water that were to get behind the coating to quickly pass out of the system.

Until the mid-20th century temperature and air quality in interiors were achieved by working in harmony with the surrounding environment. Orientation of the doors and windows, shading from trees and bushes, eaves and attic design were critical elements of construction. Inevitably moisture would make its way from outside and be generated from normal activities within the home. It was necessary to have breathable building systems that allowed moisture to find its way out.

With the industrialization that accompanied two world wars and the development of mechanical HVAC systems, building design changed rapidly. Now a building of virtually any shape could be placed on a cleared piece of land irrespective of shade or orientation. Electrically powered HVAC systems would guranantee a comfortable environment. The following two factors became of primary importance in modern building cladding design.

Most critical was waterproofing the building envelope. A cladding system that could effectively stop the passage of water and significantly restrict vapour flow was now favored over traditional coatings that "breathed", absorbing and releasing water and vapour. Advancements in synthetic material production resulted in highly effective water barriers for the market. HVAC would now regulate humidity and temperature.

A secondary concern was insulation. Mechanical systems were now the primary means to control temperature and they consumed electricity. Initially fossil fuel power plants could provide cheap electricity to meet the limited demand. But as more buildings were constructed with HVAC systems energy prices rose sharply.

EIFS, in continuous use since the 1960's, does a good job in addressing these two concerns of modern building design. When properly installed it provides a watertight wall system. The foam panels have significant insulative value and the membranes of vinyl sheathing or liquid applied coatings provide good barriers to the passage of vapour that would otherwise result in an adverse loss or gain of heat depending on the season.

Significantly because of these energy saving properties of EIFS it has been classified by some as a "green" building system. EIFS manufacturers have worked hard to reduce Volatile Organic Compound (VOC) content of their synthetic components, have localized manufacturing and use as much recycled content as possible to assure their products can contribute to Leadership in Energy and Environmental Design (LEED) accreditation for certain projects.

What makes a coating or building system "green" however? Energy savings? Sustainability of resources? Biodegradibility of materials? Environmental impact? Effects on indoor air quality and human health? That is the subject of a heated debate in the industry and will be repeatedly addressed in this series of articles as we compare coatings and systems.


Contributed by Patrick Webb