Finishing, treatment and maintenance of southern limestone

This is a two-part process :
- dry sanding beforehand to get rid of any sawing marks ;

- covering with the right adaptor to protect the stone from dirt (southern limestone is very sensitive because of its porosity)

DRY SANDING
This can only be undertaken on perfectly dry material, which means that outside flags can only be sanded in summer

When there are natural holes in the stone due to shelly splinters, these must sometimes be filled in.

Dry sanding with a sanding machine is not particularly difficult except when the joints have not been done properly (cf. the principles of placing)

Stone floors with inset cabochons (terracotta, marble, wood….) are a specific case requiring a different type of sanding. Indeed, a sanding machine must not be used in this case as it could project pulverulent material onto the white of the stone. This is indelible ! The only solution in this case is to sand on kneeling down with a bordering machine. Another way is to place the cabochons after sanding.

TREATMENT THROUGH IMPREGNATION
Treatment is carried out to protect the material from household stains. It is done on a surface which has been dry-sanded. The products used for this must be meant for this use and remain microporous after drying (to let the stone " breathe "). The colour will not be spoilt. For indoor floors it is possible to apply a wax finish.

On outdoor terraces, invisible treatment will be covered by an algicide to delay the growth of parasite mosses.

Southern stone can be treated against graffiti by applying a coat of product which, in the event of tags being done on the stone, can easily be washed down by spraying with hot water.

On surfaces which have not been treated beforehand, tags can be erased even on the most porous of material. Stains on stone inside old buildings and on statues can be erased using a technique called peeling.

(Extracted from the Technical Guide of Southern Stone Association)