Obut have produced their own special boule cleaning spray.
To help keep your boules in good condition it should be applied after every session or once a month if the boules aren't being used.
To use the spray apply a small amount on the boules and then wipe with an Obut cloth.
The can contains 50ml of spray. It is not dangerous to people or the environment.
If you like you can just buy individual obut wiping cloths. They are wear resistant and are made out of absorbent machine-washable microfibre (80% polyester, 20% polyamide).
The dimensions of the cloths is 20 X 20cm. They may look small when you first open them but they do a brilliant job.
You can buy a whole pack of 12 cloths to get better value for money.