Understanding Slate

Brazilian Black Slate
Brazilian Black Slate

In our showroom in wellington, somerset. We have noticed an increase in customers wanting to know the ins and outs of slate and the process in how they are made and what the different finishes before being sealed really mean.

We are finding that the most popular slate at the moment is Brazilian.

Available in grey/greenish and black often used for Wet-Rooms both on the wall and floorDSC_1075 and available from stock in sizes of 900×900, 900×600, 600×600 and 300×300 though other sizes are avalible to order.


Slate is a fine-grained, foliated, homogeneous metamorphic rock.  Foliation is caused by strong compression causing fine grained clay flakes to regrow in planes perpendicular to the compression. When expertly “cut” by striking parallel to the foliation, with a specialized tool in the quarry, many slates will form smooth flat sheets of stone which have long been used for roofing and floor tiles and other purposes.

Because slate was formed in low heat and pressure, compared to a number of other metamorphic rocks, some fossils can be found in slate, sometimes even microscopic remains of delicate organisms.

Slate that comes from the UK, China, Spain or Canada are produced by metamorphism. These seams can contain twists produced by geological activity.

Brazilian slate is actually a sedimentary rock or mudstone, with significantly different properties. It cleaves very cleanly, and all rock deposits are naturally very flat. This gives a very consistent appearance.

Slate can be Hand split or calibrated,  Honed or Riven.

Honed slate is when the surface of the slate has been ground to a smooth, flat, consistent surface. It also means, in the case of normally shiny stones such as granite or marble, that the polish or shine has been removed leaving a matte (unpolished) surface.

Riven Slate is a natural cleft face of stone, achieved by splitting blocks of stone along natural laminations, formed by strong compression of fine grains forced to grow perpendicular to the compression. Here is a link to a video to see hand splitting being done. Hand Splitting slate.

Calibrated slate is machined on the underside to give a consistent thickness making it uniform in depth.

We recommend cleaning, sealing and maintaining with LTP Products, and the link here will help you identify what surface you have, what finish you would like to achieve and what sealers you will need.

Different methods of sealing can achieve different looks.


Cleaning tips for slate wall and floor tiles

When is sealing or deep cleaning required?

  • As an important stage in the installation process of wall and floor tiles.
  • Where poorly maintained slate floors need a top up seal.
  • When restoring slate wall or floor tiles.
  • For routine cleaning of unsealed external patios and paved areas.

Why would newly installed wall or floor tiles require intensive cleaning?

Keeping slate wall and floor tiles scrupulously clean before and during the fixing process, is vitally important.

Intensive cleaning of slate floors and walls before application of the correct protective sealing product will make sure the result does not disappoint. Installing slate flooring and worktops by nature creates grit, dirt and adhesive residues. Ensuring that a vacuum is used (being careful not to scratch the surface) to remove loose dirt from your new slate floor or worktop will not address stains and residue marks.

Simply washing slate flooring in water will not be effective in removing ingrained marks or adhesive. Using standard household cleaning products that often contain bleach is likely to damage the surface of your newly installed natural stone floor or wall. You should make sure that the correct cleaning product is used for the slate being installed. Need more information about surfaces? Visit our identify your surface selector.

Sealing of slate guide can be downloaded here: LTP application guide.

Please note that this information is offered as general guidance only and without guarantee. Your specific circumstances may need an alternative approach. In case of doubt, any process should be tried out in an inconspicuous area before general application.


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