Why CPVC matters for plate-like fillers
Critical pigment volume concentration is the point at which there is insufficient binder to fill the void structure and fully wet the pigment/filler surface. Near or above it, permeability, water uptake and loss of cohesion can increase. The risk must be assessed for the complete pigment package, not glass flake in isolation.
Because platelet surface area changes with thickness and PSD, equal weight additions can represent very different resin demand. Fine or thin grades may require a lower loading or a different rheology package than coarse grades.
Build a loading ladder
Screen several additions around the expected operating point while holding resin, pigment package, cure and film build constant. Measure grind quality, viscosity, density, pot life, application response and cured-film defects at each point.
Then test the most practical candidates for water uptake or permeability, adhesion and the project-relevant corrosion or immersion exposure. Plot the outcome rather than choosing the highest filler percentage.
Common signs that the window has been exceeded
Watch for rapid viscosity rise, incomplete wet-out, air entrapment, porosity, poor flow, weak intercoat adhesion, early blistering or erratic spray. These findings can indicate inadequate binder volume, poor dispersion or an incompatible additive package; they should trigger root-cause testing rather than a simple loading reduction.
Specify the validated range
Document a production range for glass-flake volume fraction, viscosity, particle distribution and application variables. A range is more robust than a single nominal loading because raw-material and process variation are unavoidable.
Engineering review checklist
- Calculate and track volume concentration, not only weight fraction.
- Treat flake thickness and specific surface area as resin-demand variables.
- Measure application behaviour before relying on barrier-test results.
- Set finished-coating acceptance criteria for the qualified loading range.
Technical basis
Use supplier data as formulation inputs, then validate the finished system under the relevant service and application conditions.
Share the resin, target film thickness, application method, and service exposure to receive a grade recommendation.
Contact technical team →