In the right setting a weathered pot can look very attractive. To accelerate the natural ageing process, occasionally paint the outer surface with yoghurt or milk. If a clean surface is preferred simply use water and a stiff brush to remove algae or dirt.
For glazed terracotta, simply clean with a soft cloth or damp sponge.
Over time, the finish may change in a natural way. To revive, treat with wood preservative, following manufacturers instructions.
CEMENT BASED / FIBRE CLAY
In time, weather influences may change the finish of the product in a natural way. To revive, apply some baby oil to the outer surface with a soft cloth. Zinc can be affected by certain chemicals, so take care to avoid surface contact.