AddedThere is simply no substitute for humidity IMO in maintaining rattan in good shape. Some of the oils and waxes help, but eventually rattan does dry out in low humidity environments. Wood cracking is perhaps a more common and serious problem from low humidity. So keeping your collection warm and somewhat moist is important.
Sometime ago we had a discussion of how humid should the environment be for wood and rattan preservation, while at the same time keeping the risk of rust to a minimum. Not sure that we ever settled on an ideal value, but IIRC a relative humidity of 40-50% at a temperature of 65-70 F (16-19 C) seemed to be a good starting point, and then see how things develop. During very cold periods (such as a Minnesota winter, where -20 F and colder is common) it is hard to achieve this degree of humidity without fogging the windows and having ice form on the colder surfaces. That's a price to pay for trying to maintain tropical items in the frozen North.
Ian.
Here's a link to that previous thread: http://www.vikingsword.com/vb/showthread.php?t=952