Mortars

This is a list of historically correct lime mortars used in tombstone and monument restoration and preservation. Lime mortars have been around for centuries and are found in most historic stone structures. Lime mortars are durable, yet much softer than modern mortars found at local building supply stores. It is very important to use a lime mortar for this reason. Modern mortars are too hard for older softer grave markers made of marble, sandstone and the like. These harder mortars and concretes will do much more harm than good. The softer lime mortar acts as an adhesive and a buffer between the tombstone and base, or other monument pieces. This keeps the actual memorial stone pieces from becoming damaged over time due to, freeze and thaw and toppling. Lime mortar can last a couple of hundred years and be easily replaced when worn away, with very little to no damage to the stone. Modern mortar is a very permanent material that can’t be removed easily at best, and not at all without causing permanent damage at the least. Please see our section under BASIC STANDARDS for uses, and TECHNICAL for instructions and MSDS.

Suggested Mortars for Tombstones and Monuments

St. Astier NHL 3.5

Manufacturer – St. Astier

Product Type – NHL 3.5

Availability – Limeworks.US, and other mortar suppliers

St. Astier NHL 5

Manufacturer – St. Astier

Product Type – NHL 5

Availability – Limeworks.US, and other mortar suppliers

A second choice to buying a readymade lime mortar, is to mix a hybrid type of mortar.

Here are types of the products you will need for this mix and a recipe developed in Oregon for historic preservation.

White Portland Cement with extra lime mix to soften cement can be used to set stone in recessed base.

1 part White Portland Cement (recommended: ASTM C-150. Type 1)

4 parts Hydrated Lime (recommended ASTM C-207, Type S)

8 parts clean sand

Manufacturer – Federal, lehigh, and many others

Product Type – White Portland Cement C-150 Type 1

Availability – local const. supply stores, hardware’s, concrete companies

 

Manufacturer – Western, Chemstar, and many others

Product Type – Hydrated Lime C-207 Type S

Availability – local const. supply stores, hardware’s, concrete companies

Locate the finest and cleanest sand available. Remember: the color of the sand will tint the mortar you are mixing. Here are two choices of sands. Quikrete fine is most preferred, but the Premium Play Sand is of a finer grade and will work if nothing else is available. Glass Block sand is another several conservators like as well.

Quickrete Commercial Grade Fine

Manufacturer – Quikrete

Product Type – Commercial grade fine

Availability – local const. supply stores, hardware’s, concrete companies

Quickrete Premium Play Sand

Manufacturer – Quikrete

Product Type – Premium Play Sand

Availability – local const. supply stores, hardware’s, concrete companies

 

There is a commercial product available special ordered from Home Depot, that with added lime, closely matches Oregon’s’ recommendation also.

Quikrete White Glass Block Mortar Mix with 5 parts added hydrated lime. This type “S” mortar mixture consists of 2 parts White Portland Cement, 1 part lime and 9 parts sand. (12 parts) By adding the extra lime, the mixture is sufficiently weakened.

Mix ratio… add slightly less than1 cup of hydrated lime to two cups of the Quikrete mortar mix.

 

 

 

 

Quickrete Glass Block Mortar Mix

Manufacturer – Quikrete

Product Type – Glass Block Mortar Mix

Availability – local const. supply stores, hardware’s, concrete companies