Mix Proportions

• The ratio of cement, lime, and sand determines the strength of the mortar mix.
  
  Type S mortar is mixed with 1 part of cement, 1/2 part lime, and 4 1/2 parts of sand.
  
  Type N mortar is mixed with 1 part of cement, 1 part lime, and 6 parts of sand.
  
  The Type S mortar contains more cement relative to the final volume and as a result has a greater strength of 1800 psi compared to a 750 psi load-bearing ability of Type N mortars. Lime is the most expensive ingredient in mortar mixes. Some mixes may be labeled Type S and Type N and appear much more cheaply at the hardware store. However, these mixes are lime-free and have less strength and water tightness.
  
  

Uses

• Type S mortar is stronger and as a result is more appropriate for both indoor and outdoor uses. The mortar has a greater ability to weather the elements and act in a load-bearing capacity. It is only useful for above ground applications
  
  Type N mortar is really suited for interior load-bearing projects. Type N mortars can be used above ground or below ground and can be exposed to weather.
  
  

Applications

• Masonry projects may include use of hard brick, granite, limestone, and other bricks. The material that is used and the conditions that the material will endure determine what type of mortar is best.
  
  With moderate exposure to the elements and the use of hard bricks or granite a type N mortar will be the most appropriate mortar for the project. Softer bricks and lime that are exposed to severe conditions fair best with type N mortar, while more severe exposure of hard bricks or granite require the type S mortar is best suited.
  
  

Safety Considerations

• Mortar mixed with lime pose health risks. The greatest risks are contact with eyes or skin or inhalation. When the mix is dry, particulate matter can be inhaled. Inhaling the dust causes scratches on the internal linings of the mouth, nose, throat, and lungs. Respiratory masks are useful to prevent damage to the mucous membrane linings.
  
  Contact with the skin can cause irritation. However, longer contact may causes burns on the flesh. Burns are also likely if the skin is wet or the mortar has already had water added to the the mix. Builders should wear gloves at all times.
  
  Contact with the eyes can cause mild irritation and burning. Mix can enter the eyes as dust or as a wet mix. Protective eyewear should be used at all times when working with mortar.