Coating defect
Colour variation
Shade differs tablet to tablet within a batch, or between batches that were meant to match.
Written by the Rglax Pharma technical team, who formulate and manufacture every grade named on this guide at our WHO-GMP works in Tahliwal, Una (drug manufacturing licence NNZ/23/238). Reviewed 3 September 2026. Licences and certificates.
What usually sits behind it
- Uneven distribution of the dispersion across the bed
- Pigment settling in the dispersion during a long run
- Comparing shade under a different light source from the one it was approved under
Worth knowing
Metallic pigments shift more than conventional ones between daylight and tube light, so the inspection light has to be fixed before the shade is judged.
Every cause above is a process parameter, not a property of the material. If you are seeing colour variation on a grade of ours, send us the run conditions and a retained sample and we will work back from them — start at the contact page.
Grades formulated against it
Where colour variation is the problem the grade was made for
Metallic and pearl film coat
Solvent base metallic and pearl effect film coats, supplied in the agreed shade.
The MNaq series is a non-aqueous ready-mix film coat that gives a metallic or pearl effect finish. Each shade carries its own code, and every code runs the same way on the coater. The shade is matched and confirmed against your reference sample before the batch is released, so a repeat order reproduces the finish you approved rather than a fresh interpretation of it.
- Base ·
- Non-aqueous (solvent)
- Finish ·
- Metallic or pearl, shade on reference
Read next
- Pan speed calculatorUneven colour is uneven exposure: some tablets passing the gun more often than others.
- Logo bridgingThe film lifts out of an embossed logo or break line and spans across it, so the debossing goes shallow or disappears.
- Picking and stickingTablets adhere to each other or to the pan, and fragments of film or core pull away, leaving pitted faces.
- Orange peel and roughnessA dimpled, matt surface rather than a smooth gloss, most visible under raking light.
- All 7 coating defectsThe whole list, with what each one looks like and the parameter behind it.