Surface Characteristics: a smooth, fine grained slate of uniform, unfading Blue/Grey or Heather Blue Colour which may on occasions contain slight surface intrusions.
Standard: Roofing slates exceed the requirements of BS 680:Parts 1 (1944) and 2 (1971).
Water Absorption: less than 0.23%(Blue/Grey) : 0.16% (Heather Blue).
Wetting and Drying: unaffected after 15 cycles.
Chemical Resistance: unaffected after 10 days in 20% sulphuric acid solution. Slates are resistant to severe atmospheric pollution, acid rain, sea air and salt spray.
Density: 2700 kg/m3
Weight: typically, 20"x10" slates fixed with a 75mm head lap weigh 27.2kg/m2
Carbonaceous Carbon: 0.18 wt%(Blue/Grey) : 0.05 wt%(Heather Blue).
Heat: slates are non-combustible and are unaffected by the normal extremes of temperature.
Sunlight: unaffected by UV light.
Biological: unaffected by moss and lichen growth, rot or by insect attack