When it comes to black limestone, we are frequently contacted about just the looks of stains and valuable minerals. While this is not unusual & occurs with most limestone forms, the appearance of discoloration & mineral deposits on black limestone or darkened stone is more common.
As a result, it is possible to detect some marks forming even before applying the seal. It is frequently challenging to prevent because it is a naturally produced reaction. This blog aims to discuss some of the various things that can occur and what you should do to avoid them from happening or what you’ll do to resolve them as effectively as possible.
Sometimes the water becomes somewhat alkaline as it passes through the surface. And Because of the evaporation of this rainwater, its alkalinity increases, and eventually, the solution becomes saturated. This solution then can travel to the black limestone surface, where it begins to deposit solids like white and grey for one calcium carbonate, sometimes known as lime puffs, on the limestone surface.
The Halo Stains And The Bands Of Mineral Deposits
There are trace levels of potassium and sodium oxides in the limestone that can be activated by rainwater, which is the source of this. Even in areas where rain is mildly acidic, the concentrations of these salts in the rain will eventually become alkaline as the rainwater evaporates. Surface wetting and evaporation can result in repeated patches & bands of dampness, known as accumulation zones, on the ground surface ( rainwater pooling on the surface where it cannot run off).
During evaporation, alkaline solutions are concentrated until they reach saturation at the outside limits or edges of accumulation zones. Evaporation continues at the surface and in the pores immediately beneath the water’s surface, resulting in precipitation, crystallization, and immobilization of the salt. Halo stains are formed due to the formation of unique bands of pigmentation, as shown in the image above of limestone.
Protect Your Limestone By Using The Appropriate Sealing Product
Sealants used to improve the appearance of black limestone pavers and to help prevent them from becoming stained by organic matter on the outside must be breathable. For example, LTP Mattstone H20, LTP External Paving, and LTP Stone Oil are all breathable sealers used outside buildings.
Apart from preventing discoloration, breathable sealers will allow for the microscopic transition of moisture, helping any stored water escape through the stone beneath it, such as from the mortar and subsurfaces. However, moisture permeating the stone & sealer to the base might still dry and leave a calciferous coating on the surface.
Once the stone has been adequately dried & mineral salt deposits have been significantly reduced, as well as general filth and grime, it should be resealed with a suitable limestone sealer.
LTP Mattstone H20 is a natural stone sealing solution that is highly effective and ideal for use on the exterior of buildings. On the other hand, LTP Stone Oil is frequently used by our customers after acidic washing of the stone because it assists in re-enhance and intensifying the color.
With a foam roller or a paintbrush, apply LTP External Stone Sealer to the surface in an equal layer. As needed, continue to use additional applications at hourly intervals until the area is wholly soaked on more absorbent surfaces. If any residue sealer is still evident after one hour, it should be removed.