What causes discoloration in blister packaging?

If you’ve ever pulled a blister pack off a store shelf and noticed it’s turned slightly yellow, foggy, or uneven in tone, you know how quickly that small visual change can make customers second-guess product quality. Discoloration in blister packaging isn’t just a cosmetic issue — it can erode brand trust and even lead to entire batches being rejected before they hit the market. Most of the time, the problem doesn’t come from one single big mistake, but from small, overlooked details spread across the entire production process.

I. Blister Packaging Equipment

① Impure equipment: Dust or debris present on the blister packaging machinery can become embedded in the material, easily leading to discoloration.

② Temperature imbalances: Issues with thermocouples, temperature controllers, or the heating system can cause uneven heating, which may also result in discoloration.

II. Blister Packaging Molds

① Poor mold venting: Inadequate venting can cause the plastic to react with oxygen under high temperature and high pressure, leading to "burn marks" on the packaging.

② Excessive lubricants or mold-release agents: An overabundance of these substances can cause discoloration. Molds should be cleaned regularly, and any residual anti-static additives should be removed.

III. Blister Packaging Sheets (Raw Material)

① High moisture or volatile content.

② Thermal decomposition of colorants or additives.

③ Contamination of the blister packaging sheets.