For binary solid mixtures, the mixture just-suspended speed is predicted with reasonable accuracy from the sum of powers to suspend the solids individually. Exceptions to this behaviour occur for mixtures of low-density solids and for mixtures involving a small, high-density solid. For these systems, summing the powers required to individually suspend the solids over-predicts the mixture just-suspended speed. Limited testing of ternary solid mixtures indicates that summing the powers required to individually suspend the solids also predicts the just-suspended speed in these more complex systems.