Mixability describes how easily and without lumps a protein powder dissolves in liquid. It depends, among other things, on the type of protein used: whey isolate usually dissolves more easily than some plant proteins or heavily heat-treated variants. The order of the ingredients and the amount of liquid in relation to the powder also affect how evenly everything combines.
The preparation itself also influences mixability, for example whether the liquid or the powder goes in first and how vigorously it is shaken or stirred. Cold liquid often dissolves powder more evenly than very warm liquid, in which individual proteins can clump more easily. A good shaker with a sieve can further help dissolving. Plant protein blends can, depending on their composition, take somewhat longer to dissolve completely than pure whey products.
Practical tips for even preparation are offered by the guide Mixing a protein shake properly, and more on suitable accessories is explained in the entry Shaker.
