Chris, A fair amount of my track is OZ Track from PAMAK Hobbies at Bargo NSW. It has been out in the open for about 10 years and the sleepers have not deteriorated much at all (think they may be Aristocraft which are not available anymore). http://pamakhobbies.com/products/ I am busy saving to buy more for the new layout. The other rail I have (AMS) the sleepers have been seriously UV affected hence my decision to put it indoors on my new layout. I have heard on some US sites that they use armourall to protect their sleepers(ties).