I'll adlib from facebook comments, but Motiv has a new trick coming to the market with a new coverstock technology that they are saying isn't reactive, and isn't urethane.
Motiv Covert Tank
Cover: Frixion Microcell
Core: Torx 2.50 RG .051 Diff
Color: Solid Black
Logo Color: Dark Gray Pearl
Box Finish: 2000 Grit LSS
"Cover (it's not urethane....isn't resin either)
The revolutionary microcell polymer cover comes from year of research in cover technology, durability, and oil absorption. Currently, bowling balls are either high absorption or non-absorbing with virtually nothing between. When Motiv set out to create the ultimate competitive advantage ball, we began experimenting in microscopic variations of oil absorption. What we developed was a brand new cover that absorbs oil at a fraction of the speed of resin, but is still capable of absorbing oil. To the naked eye, the microcell polymer cover appears to absorb no oil, like a urethane cover. However, this microscopic adjustment creates more continuation through the pins and therefore better carry. This continuation comes without sacrificing traction. With oil absorption rates as slow as the Frixion microcell polymer cover, the Covert Tank provides long life and durability as well."