Propylene Glycol n-Butyl Ether PnB (Coalescent Agent)

Coalescent level depends on the latex MFFT (minimum film formation temperature) relative to the application temperature. Rule of thumb: 1% PnB reduces MFFT by approximately 1–2°C for hard acrylics (Tg >20°C). For a latex with MFFT of 15°C applied in 5°C conditions, you need 5–10°C reduction, requiring 3–6% PnB. However, excessive coalescent (>10%) reduces dry hardness (slow solvent escape) and increases VOC. Always verify final MFFT with the ASTM D2354 test after adding coalescent. For zero-VOC formulation targets, use reactive coalescing monomers or high-Tg latex blended with a low-Tg component to lower MFFT without chemical coalescent.