My sculptures are made from resin into which bronze or other metal powders have been suspended, If bronze, it has then been patinated as you would a foundry cast bronze.  The patination process reacts with only the very top surface of the sculpture, making the mutable finish very fragile.    Whilst the Resin itself is a strong material suitable for outdoors, the patination needs to be protected from the rigours of nature.  

In most situations it functions just like a true bronze/metal, expanding and contracting with heat and cold.  Resin is recommended to temperatures not exceeding -10° C.  If you are concerned, the sculpture can be protected from particularly harsh weather by wrapping in bubble wrap

If any part your piece has a natural verdigris finish (blue/greens), then this should be left unwaxed.  Doing so would darken the colour and the subtle shades would be lost.   This finish is perfectly suited to outdoors.

All other areas will have had several layers of a hard micro-crystalline wax applied to protect the surface from the harsh effects of acid rain, wind erosion and frost which would eventually damage even the  toughest of materials.

 In order to preserve the look of your sculpture, it will be necessary to follow a few simple maintenance instructions:

Do not allow snow to build up, as this may prevent the natural movement of the sculpture and may cause cracking.

Avoid over-handling with any patina, as the acid from fingers can damage the surface and leave greasy marks

Remove any bird droppings with a damp cloth (Birds love to perch and pose in the most inconvenient places).

Apply wax to your sculpture.  Liberon Beeswax (Clear), obtainable from any hardware store is perfectly good.  Use a brush to get into any crevices. Spread evenly, do not allow the wax to build up too much. Leave overnight and then buff up with a soft cloth, or clean boot-brush. This should be done once or twice a year, in spring and autumn, or whenever you feel it necessary.  When you apply the wax, the colour will  become temporarily darker (do NOT wax the verdigris finish) until the wax dries, then the surface will appear dull.   Buffing with a  soft shoe brush will return the sheen and seal the sculptures surface.  

With this small amount of preventative action you will be able to enjoy your sculpture for many years to come.