A lot of people are confused by stucco and plaster when they look at old homes. While they're alike in many ways, they differ enough that knowing how and when to utilize stucco, particularly in renovations, is crucial.

The differences are not visible to the untrained observer. Both stucco and plaster can be applied in the same method, using the same texture and thickness; however, the primary ingredients that make them are the main differences between the two things.

Plaster versus Stucco

As we mentioned earlier, the ingredients are the key to distinguishing between these two comparable construction materials. Both are made from an aggregate of a certain kind, generally, sand, which comes in a variety of dimensions and textures. Both require water to mix the materials and to activate the curing process.

The most important distinction is in the binder. The binder holds everything together and cures into the hard, rock-like consistency we all love and hate.

Plaster

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

• Lime - Prior to the mid-1900s, it was the main binder of any plaster. Prior to this, it was less expensive to purchase than gypsum plasters. Lime plaster involves 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 requires the addition of fibrous materials like horsehair to make the wall stronger. Lime plaster can take an extremely long time to cure, often taking up to a year before walls can be decorated or painted.

• Gypsum - Perhaps you've had the pleasure of hearing about Plaster in Paris? That's gypsum plaster. The name was coined due to the fact that in the 1700s, Paris was constructed on top of the biggest natural gypsum deposits anywhere in the world at the time. The majority of gypsum plaster was sourced from Paris, which is why it was named after the city. In contrast to lime plaster that cures rapidly (only several days) and sets much quicker, which is the reason we cast injured limbs using this material. It doesn't typically require horsehair to help strengthen it, unlike lime plasters.

Stucco

So, you're aware of the definition of 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 unlike lime plasters.

Like lime plaster, it is composed of slaked limestone (or various different natural binders that aren't as common, including sand and water). It also contained many additives to aid in its ability to resist the elements. According to the National Park Service Preservation Brief 22, stucco could contain some of these unique 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 the amounts of water required and reduced the time required to set. Additionally, alcohol was an air entrainer.

All of these ingredients have contributed to the durability and strength of the historic stucco. It was in 1824 that a brand new invention revolutionized the method of using stucco in building construction.

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