Mixability, and the lump in the shaker

A common customer complaint in this category is not about potency or value. It is that the powder did not mix.

The complaint you will actually get

Lumps in the bottom of a shaker, a gritty texture, or a layer of undissolved powder. It is the thing people mention in reviews and the thing that stops them reordering, regardless of how good the formula is.

It is also mostly a physical property question rather than a formulation quality one, which means it is fixable.

Why fine powders lump

Counterintuitively, finer is worse. When very fine particles meet water, the outer ones wet first and form a gel layer that seals the rest of the clump away from the liquid. The inside of a lump stays dry.

Some ingredients are worse than others: anything that gels readily, and anything hydrophobic enough to resist wetting at all.

And a powder that has taken up moisture in the tub has already begun to agglomerate before it reaches the shaker.

What helps

Instantizing, where particles are agglomerated into porous granules that water can penetrate rather than seal. This is why instantized whey disperses and unmodified whey does not, and it is a purchasing decision rather than a process you will run.

Lecithin and similar wetting agents, which reduce the surface tension barrier.

Particle size control, avoiding the very fine fraction that causes the problem.

And moisture control in the tub, since agglomeration begins before the customer opens it.

Setting the instruction

Liquid first, then powder, is the order that works and it is the opposite of what people often do. Powder into water clumps; water onto powder in the bottom of a shaker clumps worse.

Say so on the label, and say how much liquid. A product that mixes badly with 200 ml and well with 350 is not a bad product, it is an under-specified instruction.

References