In the Middle Ages, several artists would have worked on the creation of a polychrome sculpture: the sculptor’s work would have been finished off by a colour painter and a gilder. 
Restorers' colour application
diagram. This statue was carved from a block of grey-white limestone, in high relief: unlike a work modelled in the round, the subject depicted is not completely detached from the block.
Nostre Dame probably stood against a wall because only the back of the head is sculpted, the rest of the back is merely roughed out (flattened out with a claw chisel, or gradine). Signs of smoothing with a rasp are visible all over the front of the sculpture, with the exception of the furred parts of the clothes.
Holes have been bored into the crown and the collar of the Virgin’s dress in order to insert beads and decorative studs. The hands of the Child, now lost, were probably sculpted separately and assembled afterwards.
Colours were usually laid on top of a filler preparation; this is the case here, with the exception of the very pale pink flesh, where the paint has been applied directly onto the smoothed stone. The gold leaf has been laid on top of a pale yellow size.
Restorers' colour application
diagram.
Detail.
In other respects, refined techniques were employed: glazes (thinner, transparent layers of paint), red on the Child’s cloak and green on its lining, and particularly a decoration of pressed brocade on the cover of the book being held by the Virgin. (Brocade is a rich silk fabric with raised patterns created in silver and gold thread.) For a sculpture, these patterns were produced in several stages: a sheet of tin was stamped in a wooden mould, applied to the stone sculpture between two layers of ochre size, and lastly covered with gold leaf.