Posted: Mon Sep 02, 2002 10:35 am
Winter will soon be over us - and we are wondering what it will do to our flagstones if we are to use salt/mixed with sand on the paths to make sure the area is cleared from snow and ice?
It depends on the type of flags. Hydraulically pressed, uncoloured concrete flags and stone/slate flags are generally unaffected by salt, but the coloured wet-cast types, popular for patios, can suffer, particularly with the so-called de-icing salts, rather than common or garden Table Salt {NaCl}.
The de-icing salts can react with the pigments used to create the colour in the flags and make them go all funny. Reds turn to browns, buffs go quite dark and some of the darker greys/charcoals can turn either very, very black or actually be 'bleached'. It seems to depend on the actual 'salt' used and the type of dye used in the manufacture of the flag.
As with any 'chemical' treatment of paving, it's always best to test a small, discreet corner of the paving before trying it out on the main body of paving. If at all possible, try not to use salt in clearing the ice. Quite often, a spadefull of grit sand sprinkled over a frosty or icy surface ius enough to provide adequate traction, and there's no chance of the run-ff contaminating the adjacent garden, as happen with table salt and the de-cing salts sold at BMs and the DIY sheds.