The storage unit seen in the picture was actually a third story location. I have since moved to one closer to my home in the US (no address disclosure will be provided Yes Sir) where it is a second story unit. The main reason for doing so is that, during my absence, the locations I have in which to store them is limited and not adequately controlled for cold temperatures. I have experienced wrap cracking issues many years ago and am trying to avoid it during a period where the cost of storage is not cramping me too much. When home, they reside in a protected area that is heated and away from too much light exposure. I haven't had issues with high temperature because it is not common to my geographic region. However, cold is definitely an issue.
I generally keep updated pictures of my collection for insurance purposes. I actually only have 4 sets in storage at this time and in a smaller less expensive unit. I have one set with me and it is kept in an air conditioned room when not in use. Use is commonly in the evening when temperatures abate considerably.
Three out of four of the wraps on my stored sets are the more fragile types: Onyx, Strata and Ripple. All subject to splitting, so I try to be careful because all three are currently fine in that respect. The fourth in storage is jet black. The prior (original) owner had a crack propagate from the seam on the knobby mount side all the way up to the region of the mount. Surprising for that type of wrap. I had to have that one drum recovered. So it can happen to any of the wraps, and it seems Rogers drums are a bit more prone to that type of long-term behavior. Their sparkles tend to craze, have little cracks and splotch a good deal.
I've come to think that it was harder to stabilize wrap on the outer maple ply than it was, for example, with the mahogany plies of a Ludwig or Slingerland drum. It could have been the adhesive they used and it could have been something to do with the wrap they purchased. I have seen drums finished with strata where the entire seam is fractured. I suspect that the adhesion at the lap was stronger than the wrap itself, and so the wrap failed under shear stresses as the drum expanded during wide temperature swings. I have never seen that behavior on the drums made by other manufacturers.
I do know from the study of material sciences in the 70's that time-dependent failure of the plasticizer molecule chain was an issue that took some significant work to resolve. Anyone who had a car in those days knows that the interior plastics, especially the instrument panel and soft portions facing the windshield had massive cracking issues. Ever own an MG in those days? Car Driving2
I'd be curious to know if Delmar has solved that issue with their new wraps.