Once you get your sculpture you will need to think carefully about where you place it. Not in a very sunny or windy spot, you want your willow to be protected from drying elements if you can. It will have been treated with a wood ?presevative, usually 50/50 linseed oil and turpentine substitute mix applied with a mister sprayer ( my plant mister!) I would do this every 6 months to help give your sculpture a longerlife, but always be aware of staining yourself and area you spray over.Always read intructuions carefully when using wood preservatives,I  do not hold any responsibility for your aftercare, its only a suggestion.