Picking and Sticking

Tablets momentarily stick together, often just after they pass through the spray zone, and then break apart leaving defects in the surface of the coating where pieces of coating have been removed.

ISSUE CAUSES RECOMMENDATIONS
Tablet Core Tablet surface curvature is not sufficient to prevent tablets sticking together.
  • Change tablet shape to increase curvature on faces of tablets, and on the edges for tablets that are capsule shaped. Learn more.
Coating Formulation Coating formulation has a low glass transition temperature (Tg), causing it to become tacky under normal processing conditions.
  • Consult with Ashland to select an Aquarius™ film  coating system that is non-tacky under normal processing conditions.
Coating Process Coating becomes tacky because of overwetting during application of the coating.
  • Increase pan speed to reduce dwell time in the spray zone.
  • Reduce spray rate and/or increase processing temperatures to reduce overwetting effects.
  • Increase atomizing air pressure to get more effective atomization of coating liquid.
  • Ensure that spray gun setup has been optimized so that there is no mis-spraying, that all spray guns are spraying at the same rate, and that each is providing the same area of coverage over the tablet bed surface.
Coating becomes tacky because of low Tg of coating formulation.
  • Reduce processing temperatures and/or increase spray rate.