Capsule filling · Industry glossary
Capsule brittleness
The tendency of a capsule shell to crack or break under force with little permanent deformation.
Also called: shell brittleness; brittle capsule shell; capsule cracking tendency.
Can a harder capsule still be brittle?
Brittleness concerns failure with little permanent deformation; hardness or a compression-force value describes another aspect of response. Early compression modulus or yield behaviour can be similar between shells whose rupture behaviour differs. A single stiffness value does not fully describe brittleness.
A claim of “stronger capsules” therefore needs the actual result: force at a defined point, deformation before fracture, impact response, or a stated fraction broken under a stated test. Do not replace these different observations with one unqualified strength ranking.
Why can drying increase gelatin capsule breakage?
Water acts as a plasticizer in gelatin shells, so losing it can reduce their ability to accommodate force. Low environmental humidity, hygroscopic fills and desiccant exposure are possible contributors to water loss. This is a mechanism to investigate, not proof that every crack has that cause.
Compare gelatin and HPMC behaviour under stated storage and moisture conditions. A material comparison outside one grade’s recommended conditions does not establish that another grade never cracks or breaks.
Comparing capsule brittleness tests
Retain whether the shells were empty or filled, the conditioning environment and duration, shell grade and size, loading method and endpoint. Impact, deformation, tube-type loading and tensile separating-rod arrangements stress specimens differently. Their results are not interchangeable pass/fail scales.
Choose a loading arrangement that represents the failure being investigated. A result from one fixture cannot establish performance at every filling or packaging station. Comparing methods requires their actual procedures and results; a general description of an instrument is insufficient to set an acceptance limit.
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