Stone Restoration

Jahn M70 stone restoration mortar is a cement-based material that has been developed especially for the restoration of natural stone elements, natural stone parts and/or natural stone elements of facades. These parts can also include ornaments, ornamental bands, balustrades, etc.; also statues and other works of art can be restored excellently with Jahn M70 stone restoration mortar. Admittedly Jahn M70 stone restoration mortar cannot replace the natural stone, but it is an excellent mortar for its restoration.

The Jahn difference

Jahn mortars overcome traditional limitations such as layering, shrinkage, freeze/thaw, and salt to name a few. Each type of Jahn mortar is formulated in the laboratory to match the physical properties of the specific type of masonry being repaired. Jahn mortars provide a chemical bond without using polymer bonding agents.

Everest Projects Using Jahn

The Imperial Oil Office Tower on St. Clair Avenue is a landmark in Toronto. Its exterior is constructed entirely out of limestone, a high cost original investment intended to last for many decades. Chips were blowing off of the panels of stone and patching had been attempted in the past using an compatible repair compound which was now failing. The Jahn repair mortar was chosen for its compatibility with the existing material for a long lasting repair and for its ability to satisfy the cosmetic requirements of the property.

The various damaged areas were accessed with a swing stage. All of the deteriorated stone was removed by hand chipping and grinding and replaced with the Jahn repair mortar.


At 2 Lombard St., large red sandstone window sills were suffering from water damage resulting in delamination and decomposition of the top surfaces. The sills had originally been cut from a quarry which no longer exists and the cost of full replacement of the sills would have been prohibitive. Additionally, as the property is of historical significance it was important to preserve as much of the existing material as possible. Jahn Red Sandstone repair mortar was color matched to the existing stone and used to rebuild the top surfaces of the damaged sills.


Preparatory work: Cut away all loose and deteriorated stone in the damaged area until sound stone is reached. Then cut an additional 1/4″ to 1/2″ to remove stone that may be in the process of decay. This can be done with a tooth chisel in order to leave the best surface to apply the repair mortar to. The minimum depth you can apply Jahn mortars to is 1/4″. Once the deteriorated stone has been removed use a hammer and chisel or saw cut to square all outside edges of the area to be patched. (See Diagram A.) Do not leave feathered edges. Stone cutting tools as used in stone carving are the most efficient for this purpose and are the least destructive on the building.

Everest Restoration, Stone Restoration

Clean the cut out area with a stiff brush and water to remove all dust and debris. Wet the stone prior to beginning the application of the mortar.


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