English Heritage are to attempt to clean the Rollright Stones, on the Oxfordshire-Warwickshire border in England, using a vet's high-tech ultrasound normally employed to remove plaque from animals' teeth.
    Around 70 stones were daubed with yellow paint on the night of the 31 March in a suspected "April Fools" stunt. Removing the paint has been complicated by the need to protect the rare lichen growing on the stones.
    Druids have held cleansing rituals, and conservationists have tested various chemicals in a bid to leave the lichen - said to date back to 1100 CE - undamaged, so far without success. Now they have turned to Peter Aylmer, a vet from Chipping Norton Veterinary Hospital with ultrasound descaling equipment.
    Mr Aylmer said "It is used for descaling dogs' and cats' teeth, to get the plaque off. The idea is that the ultrasound probe does not damage the fabric - you get the plaque off without damaging the enamel. We are hopeful we can get the paint off the stone without damaging what's underneath."
    Dohn Prout, the Rollrights site manager, said "It looks like it might be hopeful because when the manufacturers get the equipment back for repair they test it on dried paint on a tin can. So we know it works on paint but we do not know the effect it will have on the stones."

Source: BBC (2 August 2004)