1. PVC — Pigment Volume Concentration
Definition: Volume of all pigments + extenders divided by the total volume of non-volatile components (pigments + binder), expressed as %.
PVC (%) = Vp ÷ (Vp + Vb) × 100 where Vp = total pigment volume, Vb = total binder volume
- Controls hiding/opacity, whiteness, and gloss level.
- Affects film strength, scrub resistance, and water resistance.
2. CPVC — Critical Pigment Volume Concentration
Definition: The maximum PVC at which the binder just fills the spaces between pigment/extender particles, with no air voids in the dry film.
- Premium exterior acrylic: ~ 50–55 %
- Interior acrylic emulsion: ~ 45–55 %
- Alkyd enamels: CPVC ~ 20–25 %
3. Relationship Between PVC and CPVC
- PVC < CPVC: Binder-rich, dense film → higher gloss, strong, low water absorption.
- PVC ≈ CPVC: Often the optimum balance of hiding vs durability.
- PVC > CPVC: Porous, dead-matte film → high initial hiding but weak and chalky.
4. Effect Summary
| Property | Low PVC | Near CPVC | Above CPVC |
|---|---|---|---|
| Hiding / Opacity | Low | High | Very high initially |
| Gloss | High / semi-gloss | Low / eggshell–matte | Dead matte |
| Film strength | Strong | Good | Weak, friable |
| Water absorption | Low | Moderate | High |
| Scrub resistance | High | Good | Poor |
5. What counts as binder in PVC?
For PVC calculation, the binder volume is based only on its solid, non-volatile content:
- Acrylic emulsion → only the polymer solids
- Alkyd resin solution → only the alkyd solids (e.g. 60–70% NV)
- PU / Epoxy systems → only the resin + hardener solids
Do not count:
- Water
- Solvents
- Coalescents, plasticisers, glycols
- Volatile bases (ammonia, etc.)
6. Why is binder taken at 100% solids in PVC?
PVC is defined on the basis of the dry film (non-volatiles):
- Pigments + extenders → remain as solid particles in the film.
- Binder → remains as a continuous solid phase after drying.
- Water/solvent and other volatiles → evaporate, so they are not part of the PVC calculation.
Therefore, PVC uses only the volumes of pigment solids and binder solids.
7. Correct binder volume for PVC
The binder volume used in PVC is calculated like this:
Example (acrylic emulsion):
- Emulsion = 100 kg
- Non-volatile (NV) = 50%
- Density = 1.04 g/mL (≈ 1.04 kg/L)
Then:
- Binder solids = 100 × 0.50 = 50 kg
- Binder volume = 50 ÷ 1.04 ≈ 48.1 L
This 48.1 L is the only binder volume used in PVC calculation.
8. PVC formula with binder solids
After calculating pigment volume (Vp) and binder-solids volume (Vb):
9. Practical checklist for formulators
- Always convert binder to solids first (wet weight × NV%).
- Always divide by density to get binder volume in litres.
- Never include water/solvent/coalescent volume in Vb.
- Pigment and extender volumes should also be calculated from weights and true densities.