Driven by a desire to reduce printer power demand by lowering the temperature requirements of the fuser, it has become common for lower softening temperature resins to be employed in toner. One consequence to the use of these resins is an increased risk of blocking during shipping or storage at elevated temperatures. By extended exposure of toner samples to elevated temperatures we propose to identify and evaluate the material characteristics most relevant to robust ship/store performance. As observed previously, low Tg or onset of flow temperatures (Shimadzu) can contribute heavily to temperature induced blocking but are not necessarily a guarantee of ship/store failure. Failure can be accompanied by absorption of surface additives into the toner particle. High levels of additives can significantly improve blocking resistance.