In-filling of Logos/Break Lines

Coating droplets are over-dried before contacting tablet surface, increasing tablet surface roughness and filling in the logo, thus reducing logo/break-line clarity.

ISSUE CAUSES RECOMMENDATIONS
Coating Suspension Suspension solids are too high, creating viscous suspensions that are difficult to atomize finely.
  • Decrease suspension solids content.
Coating suspension is too foamy.  Learn more.
  • Improve mixing process by setting mixer height correctly.
  • Choose mixer blade of correct size (about 30% of tank diameter).
  • Choose optimal mixer speed, and incorporate powder into water quickly to avoid excessive viscosity build-up before all powder has been wetted out.
Coating Process Drying conditions are excessive for spray application rates.
  • Decrease drying air temperature.
  • Reduce turbulent airflow by ensuring optimal pan negative pressure is maintained.
  • Increase spray rate.
Spray gun operation is not ideal for process.
  • Decrease atomizing air pressure, if excessive.
  • Adjust gun-to-bed distance to maintain adequate spray coverage while minimizing drying of droplets prior to impact with the surface of the tablet bed.
  • Check spray guns for optimal operation (replace any damaged parts; ensure “o” rings are properly lubricated; check for excessive material buildup on exterior surfaces of air cap). Learn more.