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En klut som ligger på en gammel skiferhelle

If you choose Scandinavian slate, you not only choose a beautiful and environmentally friendly material - you also choose a maintenance-free product that is durable for several generations and hundreds of years, regardless of temperature, weather and climate. If the slate is mounted correctly, the maintenance will generally be limited to keeping it clean.

Outdoor cleaning

Tips 1: choose a hose over the high pressure washer!

Whether the slate is glued to a concrete base, or laid on gravel or sand or on blocks (system floors), it is usually enough to flush it clean with a hose.

If you’re using a high pressure washer, avoid flushing too closely to the slate. This may dislodge some of the mica layer on the slate or make it change direction, resulting in a colour change on the surface reflecting the flushing pattern. It may also damage the joints between glued tiles.

A close-up of a crazy paving slate of Offerdal slate with built-in-lighting.

Tips 2: Use a detergent ment for natural stone

With extremely ingrained dirt or if moss has begun to grow, a general cleaning agent suitable for natural stone may be used.

Tips 3: How to remove moss

Moss only grows on the surface. Some species are only loosely attached to the slate, while others become very firmly attached. In the latter case, it’s a good idea to moisten the slate a few hours before washing/scrubbing.

Add a few drops of washing-up liquid to the water. This lowers the surface tension, making wetting more effective and the subsequent scrubbing easier.

NB: Don’t use a steel brush, as residue from it may lead to rust stains on the slate.

A close-up of a Oppdal quartzite slate flagstone with leaves from a green plant hanging over.
The moss grows only on the surface and can often be loosely attached.
An illustration sketch of moss removal on slate.
Moss removal: Moisten with water with a few drops of dishwashing liquid added. Wait a few hours. Scrub with a stiff brush, then wash with chlorine if necessary and finally rinse with water

Indoor cleaning

Slate laid indoors requires very little maintenance other than clean water, perhaps with a few drops of a mild, neutral soap.

Tips 1: Avoid fatty soaps on impregnated slate

Impregnated slate has a protective membrane that makes it impervious to all types of stains. The use of fatty or waxy soaps will therefore leave a wax coating on the surface. This not a good idea, as dirt and grime will stick easily to this coating and over time the surface will appear yellow and dirty.

Tips 2: “Reset” the surface from time to time

Once in a while, it’s a good idea to use a general cleaning agent on the surface, to dissolve and remove any build-up of dirt and grease.

Stain removal

Unsightly stains on your slate tiles?

There are a number of effective special products for all types of slate. Manufacturers such as Akemi, Steinfix and Fila all have products specifically developed for natural stone and for all types of stains.

Among the products for natural stone you will find oil and grease removal paste, graffiti/paint remover, rust stain remover and organic stain remover (red wine, blood, organic stains).

A picture of a wall with a slate coping with a hewn edge.


Stains on slate will disappear by themselves over time.

But you may prefer to impregnate the slate to avoid stains in the first place. This can make sense, particularly indoors to avoid stains penetrating the slate, whether the stain is from red wine, olive oil or greasy body lotion.

A useful side-effect is that the mop or washing cloth will glide more easily over the surface, making cleaning easier.

Some of the most relevant places to impregnate are bathrooms, kitchen worktops and indoor floors, although it might also be useful to impregnate the slate area on your terrace where you place your barbecue.

Tips 1: Choose your impregnating agent carefully!

There are many different suppliers and many different products.

Some are completely invisible after application, while others contain colour enhancers. The latter will change the look of the slate and in many ways deprive the stone of its natural appearance and surface features. If you want a colour enhancer, you should make a test application to see whether the end result will turn out the way you want.

Oil-based products such as clinker oil will also have a protective effect, but these also result in quite a dramatic change to the colour of the slate.

We generally recommend choosing an invisible impregnation agent (after drying) that only has a water-repellent effect (nano, anti-stain type), without changing the character of the stone.

Tips 2: Application

Clean the slate thoroughly and rinse well with clean water, to remove all residue from soap and cleaning agents. Impregnation requires a completely neutral surface.

After the surface is 100 per cent dry, impregnating agent can be applied.

An impregnation lasts for many years in an ordinary home. It is easy to see if re-application is needed. For as long as a liquid forms drops on the surface, the impregnation is still effective.

Frequently asked questions about maintanance of slate

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Yes. Slate worktops can be impregnated with an oil-based impregnation agent that protects against greasy and oily stains. We recommend products that are invisible, i.e. that do not change the colour and gloss of the slate, and are approved for use with foodstuffs, such as Akemi Natura Impregnator or Steinfix 100+.

No, slate must not be impregnated. However, for some applications, it would be advisable to recommend impregnation, as it provides protection against stains and dirt while also facilitating cleaning. For example, it is a good idea to impregnate worktops that are exposed to grease spills, etc.

Slate requires little – both indoors and outdoors. Outside, rinsing with a water hose is usually sufficient. Clean water may be used indoors, possibly with a mild, neutral soap (avoid using common green soaps that often have a PH value that is not appropriate for natural stone). Once in a while, the surface can be coated with a coarse cleaning agent for natural stone.

Stains are easily removed with special agents which are supplied by several manufacturers. Akemi oil and grease remover paste removes tallow, grease and oil. Organic stains from wine, blood and plants can be removed using Akemi Good-Bye Stain cleaning agent. Follow the manufacturer’s instructions and neutralise the slate by rinsing with clean water after treatment.

Removing grass with boiling water from a kettle is both easy and environmentally friendly. This kills the roots and prevents rapid growth. One can also burn it off using a propane burner. It can also be removed mechanically with a rake (Fiskars) or using chemical weedkillers.

Removal of moss on a slate roof is done with water and a broom, or with a high-pressure cleaner. Moss only grows on the surface

Joints can be topped up with the same mass used when installing the slate slabs. For joints with a large width, gravel or single grit 2-4 mm can be used. Narrow joints can be topped up with a dry and fine-grained grouting sand. Weeds in joints can be removed using chemicals, be burned with a propane burner, or removed using boiling water, which is the easiest and most environmentally friendly method.

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