Filling by weight

Filling a supplement tub is the step where the blend becomes servings, and two separate label claims depend on getting it right.

Two claims ride on this step

The net quantity of contents, declared as a weight. And the servings per container, which is that weight divided by the serving size.

An underfilled tub understates neither honestly: it is short on the first and overstates the second.

Fill to weight, always

Never to a volume mark. Bulk density moves with particle size, moisture and compaction, so a volume that was right at the start of a run is wrong at the end of it.

A scale under the tub, tared, is the whole answer at small scale. An auger filler with a check-weigher is the upgrade, and it is the first piece of equipment worth buying here.

Set the target slightly above the declared quantity, because the distribution has two tails and only the low one is a compliance problem.

Segregation during filling

This is the part specific to blends. A hopper is a vessel in which powder is moving and settling, so it segregates as it empties, and free-fall into a tub segregates again.

Which means the last tubs of a run can differ in composition from the first, not only in weight. Minimize drop height, keep the hopper topped up rather than running it to empty, and fill close in time to blending rather than storing blend in bulk for days.

Check-weighing properly

From the start, middle and end of every run, recorded, all three. A trend across them is the fill drifting. A spread is the powder varying.

Take blend samples at the same three points for anything where potency matters, because the fill run is a second opportunity for the batch to become non-uniform after it left the blender uniform.

References