Sandstone can be repaired well with lime mortar

Small cracks, chipped corners and other damage can be repaired well with the right remedy. It is important to choose the filling material that "understands" the sandstone. Cement and cementitious substances are not suitable and, in bad cases, lead to later deteriorating damage.

Analyze and eliminate causes

The first step in repairing sandstone later is thorough damage analysis and root cause research. While chipped corners usually have self-explanatory mechanical causes, scratches and gaps must be checked carefully. Should structural damage "drag in" the rock, they must be worked out.

Before repairing sandstone, only "healthy" rock should be present, which is a reliable carrier for the later filler. When crumbling, any existing moisture, even under or behind the sandstone, must be dried out. If efflorescence is detected, the sandstone must be desalinated with sacrificial plaster or compresses.

Glue and lime milk

Cracks and chipped pieces of stone can be glued, but a diffusion-open adhesive should be used. The best repair and filling material for repairs is lime mortar. It is very adaptable to the hardness of the original rock and can be easily shaped and modeled.

An additional measure supporting adhesion is the use of lime before filling damaged areas. The application of lime milk is similar to the "embalming" of the inner walls of holes and cracks.

Layers and color

The fillings can be done in one shift or in several operations. A single layer thickness of more than two centimeters should be avoided. For deeper or higher fillings, another should be filled only after the setting and hardening of the first layer.

If a coloring is intended for the filler, with multi-layer application only the uppermost layer should be provided with color particles. A good alternative can be achieved with self-mixed mortar coloring by the appropriate type of sand. In any case, the rule is to follow that the filler remains softer than the surrounding sandstone.

Tips & Tricks

If you want to repair large and deep holes, you can increase the durability of the filler by inserting stainless steel pins into the "wound".

Video Board: Pointing with Lime Mortar from Lime Green Products