Well plaster in the states is traditionally know for being a lime based product, that is white in color and is applied over blue board and is finished in a two coat application, in earlier times plasters was thicker and may have consisted of hog or horse hair and was installed over wooden lathes.
Traditional plaster is a beautiful finish, that shows no trowel marks, no movement and has a soft elegant sheen, unfortunately it is also expensive which is why we see drywall or sheetrock being used in modern construction. Many clients in the historic district have wonderful examples of homes with plaster and always comment how difficult it is to find someone that is capable of properly repairing the plasters.
Venetian plaster, a term loosely used describes a lot of materials and many have very little in common with the lime stucko (yes its spelled correctly, more later) found throughout Venice. Due to the rapid growth of decorative plasters, many companies have rushed to jump on the product bandwagon. I am not saying that one product is inferior to the other; I am just trying they are different I hope this helps clarify a few things.
Many of the products found in home stores are synthetic; water based products that are for interior use only and produce gorgeous results, some look like real authentic lime plasters, until you touch them or get the wet. Many synthetic products require sealers which when dry, leave the surface feeing like plastic, many are very soft and are scratched easily, but again I use a lot of synthetics, one for the ease of use (no special primer and no special tint, unlike lime) and the cost factors, synthetics are less expensive because you do not need a special primer, special tint or special sealers, and that is because traditional products contain lime and need lime compatible basecoats, colorants and sealers.
The synthetics are good for any room in the house including bathrooms and kitchens, just make sure that you follow the manufacturers instructions in regards to sealers, I typically use polishing waxes, because many of my clients prefer a high gloss on the walls.
Now for the lime and Stuko and not stucco (for this I will be using lime plaster) . A friend from France, a master plaster applicator and instructor from at the Verona academy spent a lot of time with me teaching me about lime plasters and paints (coatings) said the stucco is concrete that is used on the mainly on the outside of buildings throughout the lower states.
Lime plasters may be used on interior and exterior surfaces, and even on concrete floors to resurface old floors (I have a Marmorino floor in the MD studio to prove this point), but lime plasters have been used for centuries in Europe on buildings both interior and exterior and when properly installed will last for decades. And FYI it was used throughout Greece and Rome prior to Venice.
Lime plasters are just that, they contain lime, good when dry, bad when wet, when the plasters are in wet form, the lime can cause skin irritation and can be very dangerous to your eyes, so aalways were glove and eye protection when working with lime products.
Lime plaster are a bit more time consuming, traditional lime plasters require a quartz or silica base coat, this is to make sure that the plaster does not delaminate and chip/ fall off of the wall which with many traditional primers for paint may happen.
Lime plasters also require a special type of colorant that is compatible with the plaster; many traditional colorants will fad due to the lime causing the color to break down, which will leave the surface chalky, cloudy and not very attractive. Many lime plaster manufacturers use their own colorant which is good to stay in the system for warranty purposes; I tend to use natural earthen ground pigments. Powder pigments are the raw form of color directly from the earth, ground up and filtered. I also use a line frown France that are a paste pigment, which come from the oldest operating pigment quarry in France, the same quarry the Michelangelo got his pigments from when paint his amazing frescoes. Natural powder or paste earthen pigment are an oxide colorant and are compatible with most lime plasters and produce great colors that will never fade, never fade, Natural oxide pigments are what was used in Pompeii and archaeologist are still unearthing structures in Pompeii and Herculaneum that still have vibrant rich colors used in the decoration.
Now the plasters, their are many types of plasters, most commonly you have filtered (smooth) and unfiltered (course). Filtered have many names the most common is Grasello, but it depends on who is making the plaster because there is no standards and common terms so manufacturers can call a product anything they like. A grasello is a smooth creamy plaster similar in consistency to peanut butter, very nice to work with and may be used in limitless color combinations and limitless techniques. You are only limited by your imagination, but the traditional way of installing a Grasello is 3 thin coats, burnished to a sheen and when dry (about 40% light than the wet plaster) will look like a polished marble with a variation in the color due to the thickness of the plaster, but the plaster is smooth to the touch, this is another issue, since many people think traditional Venetian plaster is a textured finish, its not. It’s a smooth finish that looks like it has texture, because of the variations in colors. Now it may be applied with a textured effect, but that’s up to the individual, there is no right or wrong ways, but there is a traditional way, which is smooth to the touch.
more later
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