CAPA is not an apology email or a replacement shipment. It first controls risk, then defines the issue with lots, samples, documents and field conditions, identifies an evidence-supported cause, implements corrective and preventive action and proves the issue does not recur.
Define the problem in verifiable language
Record customer, order, product, lot, quantity, discovery date, observation, photographs, samples and use conditions. Replace poor quality with observable facts such as moisture damage in identified bags, abnormal dissolution under an agreed method or the wrong label revision. Do not assign cause before evidence.
Apply immediate containment
Identify inventory, goods in transit and packaging material requiring hold, pause related repacking or dispatch and notify relevant owners. Containment prevents expansion but does not prove root cause. Match the hold scope to lot and traceability evidence rather than holding everything or releasing too early.
Investigate root and contributing causes
Compare factory retain, receiving, repacking and returned samples and review COA, TDS, production, packaging, transport, storage and application records. Separate direct cause, system cause and contributing conditions. Five-whys or a fishbone can structure thinking, but tests and records support the conclusion.
Separate correction, corrective action and prevention
Rework, replacement or credit handles the current case. A changed inspection point, maintenance plan, pack specification or training reduces recurrence. Extending a proven control to similar products or processes is preventive action. Each action needs an owner, due date and completion evidence rather than improve management.
Verify that action is effective
Review the same measures, complaint trend and execution records in later lots or after an agreed period, confirming completion without new adverse effects. Hangzhou Karn supports investigation of factory production and documents; local transport, storage, repacking and installation owners provide records and execute their actions.