Mortar Styles: Which one is right for my job?
When it comes to selecting mortar, there are more decisions to make than just color. While color will dramatically change the final appearance of your project, the style of mortar joint will also affect the finished look. Let’s talk a little about mortar basics:
1. Mortar Color – While there are innumerable choices in color, the standard colors most readily available are Grey, White, Tan and Buff/Almond. Keep in mind that much like paint, the color of the stone will appear different by using different mortar colors. In addition, lighting on your stone and the color of the surrounding objects will also affect the visual differences in your stone/mortar.
2. Mortar Grades – The American Society for Testing and Materials (ASTM) has a grading system assigning specific letters: M, S, N, O and K. Type N and Type S are the most commonly used mortar mixes as they have a bond strength of 50 PSI or greater which is more than adequate for most stone projects. Type S mortar generally has a higher percentage of masonry cement, where the Type N mortar has higher percentages of lime. Lime allows for flexibility and workability, whereas Type S generally yields a stronger bond. If you have more specific questions, you may contact a Masonry Supply company for additional information, or if you are looking for a larger variety of formulated mortars and colors.
3. Mortar vs. Concrete/Cement – Mortar mix is NOT the same as concrete and cement. Cement is classified as a binder and is usually just mixed with water. Concrete is a mix of aggregate, cement and water. The water activates the cement and holds the
aggregate and concrete all together. Mortar is a blend of sand, a binder and water. The binder is generally cement or lime, or a combination of both. Every mason, like every skilled baker, uses different ratios, or “recipes” of sand/mortar/water.
4. Mortar Joints – The final key decision is the mortar joint. While there are many many options available, the most common are: Drystack, Full or Flush, Recessed or Raked, and Overgrout or Smeared.
- Many people ask for a drystack stone believing it is a “type” of stone, when in actuality, this term refers to the installation method. This method is achieved when NO mortar is visible between the stones. Virtually any stone can be drystacked; however, generally installation fees are higher because this method is more lab
- Full or Flush mortar joints is similar to the method in which residential brick is installed. In this installation method, the mortar will be flush with the front side of the stone.
- Recessed or Raked mortar joints are probably the most common. This method is achieved by recessing the mortar by ½” to 1” from the face of the stone. In some cases, a specialized masonry tool is used while the mortar is still slightly soft and the tool is “raked” along the mortar; giving the finished mortar a slightly worn look.
- Overgrout or Smeared joint is often used to achieve a more “Old World” look. This technique is used by applying mortar slightly over the edges of the front of the stone. Generally a stone mason will then “smear” or smudge the edges more or less to the customer’s preference.