Condensation forms when the mold surface is below the dew point of the surrounding air. It may appear during humid weather, after a cold startup, or when coolant temperature is reduced to shorten the cycle. Fine moisture films can mark a glossy sheet before visible droplets are noticed.
Ambient temperature and relative humidity should be recorded with mold surface temperature. The dew point, not room temperature alone, determines the risk. Moisture concentrated near coolant inlets or cold metal masses confirms a local surface-temperature problem.
Coolant temperature should be controlled above the operating dew point unless the mold area is enclosed and dehumidified. Air leaks into an enclosure, wet compressed air, and cold hoses can reintroduce moisture. Wiping the tool treats the result for only a few cycles and may add lint or contamination.