CHINESE BLACK SLATE STEP TREADS & THRESHOLDS
BlACK Slate - HONED SURFACE
The black, honed treads / thresholds are really beautiful and are enormously popular for outdoor stairways, veranda perimeters and door thresholds. This is a black slate with a fine, silky surface. It is very dense with low water absorption properties that makes it suitable for wet and dry areas, indoors or outdoors. minor scratches may develop with time as the slate evolves in its new environment. Any scratches in the slate are easily sanded out though. Over time and with use light traffic creates an attractive patina.
The treads may be 500 million years old and have interesting wavy patterns and occasionally faint lines of intrusive quartz or sparkly gold specks - each piece has its own character.
Bullnose treads honed - 1200x300x30 & 1500x300x30 + 2000x300x30mm by special order
Honed slabs - 1200x400x30mm (by special order)
THE WORLD'S GREATEST FLOORING STONE?
If there is a more durable stone for flooring, we are not aware of it! The test results at the foot of this page are proof of the extraordinary quality of Chinese Black slate. This is truly, an exceptionally durable stone. The silky smooth honed surface is vulnerable to scratching if used on a floor but this will depend on the amount of traffic and presence of grit. No probems though, if used on walls like the shower recess in this image. Over time honed floor surfaces tend to develop an aged patina which are preferred by many, but certainly not all - so it is something to think about.
STONE QUALITY RATINGS
INDICATIVE TEST RESULTS
ASTM C629-08 benchmarks for the water absorption (weight) of slate are 0.25% (exteriors) and 0.45% (interiors)
Density (ASTM C97-02) - 2753 kg/m3
Water absorption (ASTM C97-02) by volume (porosity) - 0.63%
Water absorption (ASTM C97-02) by weight - 0.23%
Flexural strength (ASTM C880) (dried) - 29.3 MPa
Flexural strength (ASTM C880) (wet) - 22.6 MPa
SEAL IT OR LEAVE IT NATURAL?
The test results below indicate that this slate should not need to be sealed, after all it's dark colour is not likely to show the usual coffee, tea or red wine stains! So there is a good argument for saving your money. However, there are two very practical reasons for sealing.
When used indoors, some people prefer the colour enhancement provided by surface sealers and on the natural split surface cleaning is much easier as well.
To protect the slate from oil and grease stains especially around food preparation areas. Unless these are wiped up quickly, they will leave marks on an unsealed surface.