Many people confuse stucco and plaster in older homes. While they're alike in many ways, they're different enough that knowing the best time and place to use the two, particularly during renovations, is crucial.

The differences between them aren't readily visible to the untrained observer. Both stucco and plaster can be applied in the same manner, with similar different textures and thicknesses; however, the primary ingredients that make them differentiate them from each other.



Plaster versus Stucco

Similar to what we have mentioned, the components are the key to distinguishing between these two identical construction materials. Both are constructed with an aggregate of a certain kind, typically sand in various dimensions and textures. Both require water to mix the materials and initiate the curing process.

The main distinction is in the binder. Binders are what holds the entire thing together. It cures to the hard, rock-like consistency we all love and hate.

Plaster

Based on the type of plaster you've got, you'll be using two different binders, either lime or the gypsum. Let's take a look at both.

• Lime - Prior to the beginning of the 1900s, it was the main binder of any plaster. In the past, it was more affordable to obtain than gypsum plasters. Lime is a difficult process of mixing lime and water and then waiting for it to "slake" before it can be added to sand for application. Lime also required the addition of fibrous materials like horsehair to make the wall stronger. Lime plaster can take a very long time to fully cure and can take nearly a whole year to cure before walls are covered with wallpaper or paint.

• Gypsum - Have you been familiar with Plaster from Paris? That's gypsum plaster. The name came about due to the fact that in the 1700s, Paris was constructed over the biggest natural gypsum deposits found in the world at the time. The majority of gypsum plaster was sourced from Paris, which is why its name stuck. In contrast to lime plaster that cures rapidly (only two days) and sets quicker, which is the reason we cast broken limbs using the material. It doesn't typically require horsehair to help strengthen it as lime plasters do.

Stucco

You know what is plaster and what it's not, do you? What is stucco? Stucco, sometimes referred to as "render" by our neighbors across the water, is an external coating that is historically distinct from lime-based plasters.

Like lime plaster, it is composed of slaked limestone (or any of the different natural binders that aren't as common such as sand or water); it also has various additives that help it resist the elements. According to the National Park Service Preservation Brief 22, stucco could contain various unusual ingredients:

Mud, clay, marble or brick dust, sawdust, animal blood or urine, eggs, keratin or gluesize (animal hooves and horns), varnish, wheat paste, sugar, salt, sodium silicate, alum, tallow, linseed oil, beeswax, wine, beer, or rye whiskey. The oils, fats, and waxes were used to impart water repellent properties. Sugary substances decreased how much water was required and reduced the time to set, and alcohol served as an air entrainer.

All of these ingredients have contributed to the durability and strength of the historic stucco. The year 1824 saw a brand new invention that altered the way stucco was utilized in building construction.

Portland cement was first developed in the year 1824 in England and was named so because its creator, Joseph Aspdin, thought that the cured concrete resembled Portland stone which was a very popular construction material in England at the time.