Work out dry coating, suspension volume, and vehicle needed for a target weight gain.
Film coating adds a thin, functional or cosmetic layer around a tablet core, and the amount of coating material needed depends on how much weight gain you're targeting relative to the uncoated tablet. This calculator starts from that weight gain percentage and the core tablet weight to work out how much dry coating material is needed for the whole batch.
Because coating material is rarely applied as a pure powder — it's dispersed or dissolved in water or an organic solvent first — the calculator also converts that dry coating requirement into a total suspension weight, based on the percentage of solids in your coating dispersion. Whatever's left over after subtracting the dry solids is the water or solvent you'll need to prepare the batch.
If you also enter a spray rate, the calculator gives you a rough estimate of how long the coating process should take — useful for planning pan time or comparing against your actual process to spot problems early, like clogged nozzles or slower-than-expected drying.
Film coating is one of the more failure-prone steps in solid dosage manufacturing — too little weight gain and the coat doesn't fully cover the core, too much and tablets can stick together or take too long to dry. Getting the suspension weight and solvent split right before the process starts avoids a mid-batch scramble to prepare more solution, and helps keep weight gain consistent from batch to batch.
Most film coats target a weight gain of around 2–4% of the core tablet weight, though this varies by formulation and coating type.
Because coating material is applied as a liquid dispersion, not a dry powder, so you need to know the total suspension weight to prepare enough coating solution.
Read the full article: Coating Weight Gain Troubleshooting →