A compacted portion of powder formed during dosing and transferred into a capsule body.
Also called: powder slug; compacted powder dose.
Why can a free-flowing powder still be difficult to fill?
Flow into a dosing space and retention during transfer are different demands. A plug is a compacted portion intended to stay together while moving into the capsule. Clean transfer concerns dose handling, not a definition of free-flow behaviour.
A readily flowing granular formulation may resist formation of a cohesive slug. The selected mechanism must therefore accommodate both flow into the dosing space and retention during transfer.
Does an intact-looking plug prove the dose mass is correct?
Appearance describes the observed form, not its mass. Slug formation and the intended fill mass are linked but separate questions; neither a photograph nor the word “cohesive” supplies a mass result.
Compare the observed transfer with an independent mass result for the same material and mechanism. Break-up during transfer may affect dose handling, but does not identify its cause without further observation.