Do it yourself

How to clean black slate

22 May 2024

Slate is a fascinating and versatile natural stone, with a history that has its roots in antiquity. But every time we see it, our minds inevitably return to those school memories, when the blackboard was the backdrop of all our mornings. Slate is mainly composed of clay and quartz, with traces of other minerals. It is known for its dark color and ability to be divided into thin and flat slabs, making it ideal for use as a roofing material for roofs, floors, whiteboards and other architectural purposes.

In this article we will see all the best solutions for the treatment and removal of stains from black slate. In fact, how to clean black slate is a frequent question we receive.

What stains are most frequent on slate surfaces?

Before we understand how to clean black slate, we need to understand which elements stain this material most frequently. As we have already mentioned, thanks to its unique aesthetic and its ability to be cut into thin slabs, the black slate is used for coverings, covers, window sills, bathroom and kitchen tops, shower trays, tables and much more. Even, in recent years it has become very common to use it for the production of dishes and trays. Its versatility makes it a choice appreciated and sought after by architects and designers.

Despite its durability, slate is still a natural material and, as such, can be subjected to scratches and abrasions. For this reason, it is essential to know how to treat the slate correctly, both before and after laying, to preserve its integrity and original appearance. Proper cleaning and maintenance are essential to ensure the longevity and beauty of this extraordinary stone.

As we have already seen, slate is a very versatile material that can also be used outdoors.

  • Its weather-resistant ability makes it a popular choice for flooring, exterior cladding, and roofing. However, due to its constant exposure to the elements, slate can suffer damage and show signs of wear over time. The stains caused by acidic substances, such as those present in the rain and in the limestone, can cause undesirable visual effects on slate surfaces. These substances can react chemically with the composition of slate, creating white or opaque spots that compromise the aesthetic appearance of the stone.
  • Even when slate is placed indoors, the limestone present in the water is a great enemy for this material, because it can settle on the surface and create white or opaque spots. This is especially common in areas where water is hard, that is, it contains high concentrations of calcium and magnesium. Limestone can accumulate over time, creating a thin but visible layer on the surface of the slate.
  • Being often found in our kitchens, slate can also be subject to oil and fat stains. The problem with these fatty substances is that they can penetrate the porous surface and cause stains that are very difficult to remove.

Black slate: how to clean it?

How to clean black slate? Here are some good maintenance practices:

  • Cleaning slate regularly with mild detergents can help remove surface deposits and prevent the accumulation of substances that could cause stains.
  • Moreover, applying slate-specific sealants, protective and impregnating agents can help protect the surface from the penetration of harmful substances and facilitate cleaning.

In case of stains formation, it is advisable to treat them as soon as possible to prevent them from becoming permanent. There are specific products on the market designed to clean the black slate and restore its original luster. However, it is important to always test these products on a small hidden area to make sure that they do not damage the surface of the slate further.

Some products for cleaning black slate

As we have seen, the most frequent spots on black slate are caused by acid rain, limestone or by oils and fats. In all these cases, the most suitable product to remove stains is a specific and professional product such as SGRISER, a remover cleaner for the removal of old oil and/or wax treatments from cotto, stone, cement and terrazzo materials. A degreaser and wax remover of this type is perfect for cleaning slate because it cleans and degreases in depth the dirty surfaces of oils, greases and organic scale. In addition, SGRISER does not leave harmful residues in the absorbent material and does not release unpleasant odors during use and in environments.

It is recommended to spread this product on the surface and then let it act for about 10-20 minutes. After this waiting time, it is best to rub the surface with plastic fibre buffers or discs, such as RED BUFFER or RED DISC. In fact, only thanks to the mechanical action you will be able to remove stains and scale.

Once the degreasing cleaning is finished, with the clean, dry and degreased surface is finished, it is necessary to apply BRIGHTSTONE NERO: a stain-resistant primer for the correction of the color of black slates, bleached by acidic solutions or degradation due to atmospheric agents and limestone encrustations. BRIGHTSTONE NERO ensures a protective treatment and perfect to keep and shine and renew the brilliance and natural beauty of the stone.
This product is very easy to apply, it is massaged until the saturation of the material, such as the application of waxes.

Tips for ordinary and extraordinary maintenance of slate

The ideal to maintain a slate surface of its original color and beauty is to take care of this material daily using the right products. With respect to the ordinary cleaning, slate can be washed with UNIPUL, a concentrated detergent with multifunctional use, depending on its concentration in water, ideal for a intensive degreasing cleaning on all hard surfaces. UNIPUL cleans and sanitizes surfaces even at low concentrations, without damaging even the most delicate materials. This product can also be used for cleaning after laying delicate materials, such as slate, marble and polished grits. Moreover, it leaves no marks on the material and releases a pleasant scent in the rooms.

In addition to routine cleaning, we always recommend a periodic application of the primer BRIGHTSTONE NERO, to maintain and renew the brilliance of slate and bring it back to its natural beauty. Depending on the need of the surface, we recommend applying this stain-resistant primer once or twice a year.

The products presented in the article
  • 30.55€


    Protective black stain-resistant impregnation, specific for the recovery of the color of black stone materials, such as black slate, stones, basalt, granite, marble, corroded and bleached terrazzo.

  • 12.07€


    Universal detergent for ordinary and/or extraordinary cleaning of floor and wall materials. It cleans and sanitizes surfaces even at low concentrations, without damaging even the most delicate materials.

  • 12.81€


    Wax remover for removing old oil and/or wax treatments from stone materials in cotto, stone, marble, concrete, and grit. It cleans and deeply degreases surfaces soiled with oils, greases, and biological encrustations.

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