The sugar coating process for tablets is a multi-stage process used to improve the appearance, taste, and stability of tablets. Here’s a breakdown of the key stages:


1. Sealing (Waterproofing)

  • Objective: Protect the tablet core from moisture to avoid degradation.
  • Process: A seal coat is applied to the tablet using shellac or polymers like cellulose acetate. This step is crucial to ensure the core doesn’t absorb moisture from subsequent layers of sugar coating.
  • Equipment: Sugar-coating pans with air dryers or modern coating machines.

2. Subcoating

  • Objective: Build up the tablet size, round the edges, and provide a smooth surface for further coating.
  • Process: A mixture of sugar solution, gelatin, and bulking agents (e.g., calcium carbonate or talc) is applied. This stage involves alternating layers of subcoating solution and dusting powders, followed by drying.
  • Impact: The tablet size increases considerably at this stage.

3. Smoothing (Grossing)

  • Objective: Smooth out the surface after subcoating.
  • Process: Smoothing syrup (simple sugar syrup) is applied in thin layers to create an even surface. This stage prepares the tablet for the application of coloring or polishing.
  • Care: The syrup is applied carefully to avoid forming rough patches or uneven surfaces.

4. Coloring (Finishing)

  • Objective: Apply the desired color to the tablet.
  • Process: Colored sugar syrup or dye solutions are applied in thin layers. Tablets are tumbled and dried after each coat to achieve a uniform color.
  • Precision: Requires meticulous attention to achieve a consistent color across all tablets in a batch.

5. Polishing

  • Objective: Give the tablets a glossy, attractive appearance.
  • Process: Wax (like beeswax or carnauba wax) is applied to the colored tablets in a polishing pan. This step gives the tablet a shiny, smooth finish.

6. Printing (Optional)

  • Objective: Label or mark the tablet with a logo or identifier.
  • Process: Some sugar-coated tablets may undergo printing using edible inks to mark branding, dosage, or other identifiers.

Summary of Process

  • Sealing: Protects the core.
  • Subcoating: Builds size and rounds the tablet.
  • Smoothing: Smooth the surface.
  • Coloring: Applies color uniformly.
  • Polishing: Adds gloss and aesthetic appeal.
  • Printing: Marks identification on tablets (optional).

These stages must be conducted carefully, as sugar coating adds significant weight to the tablet and can affect dissolution rates if not controlled properly.