Plastic dishes tend to come out of the dishwasher wet due to their lower thermal mass and surface properties compared to other materials, such as glass or ceramics. There are several factors that contribute to this issue:
Thermal Properties: Plastic is not as dense and does not retain heat as well as materials like glass or ceramic. During the drying phase of the dishwasher cycle, the hot air inside the dishwasher will evaporate water more effectively from dishes with higher thermal mass, like glass or ceramics, leaving them relatively dry. However, plastic cools down faster, and the remaining water on its surface may not evaporate completely during the drying cycle.
Heat Sensitivity: Some plastics are more sensitive to high temperatures, and excessive heat can cause warping or deformation. To avoid damaging plastic dishes, dishwashers use a lower drying temperature than what is typically used for glass or ceramic items. As a result, the lower drying temperature can lead to less effective water evaporation from plastic surfaces.
Shape and Surface Area: Plastic dishes often have more irregular shapes and a larger surface area compared to flat glass or ceramic dishes. This means that water can accumulate in crevices and corners, making it more difficult for the hot air in the dishwasher to reach all the wet spots and evaporate the water effectively.
Water Repellent Properties: Some plastics have a hydrophobic (water-repellent) surface, which can prevent water from spreading out and forming a thin film that evaporates quickly. Instead, water droplets may cling to the surface and take longer to dry.
To improve the drying performance of plastic dishes in the dishwasher, consider the following tips:
Load Plastic Dishes Properly: Arrange plastic items so that they have enough space between them to allow hot air to circulate freely during the drying phase.
Use a Rinse Aid: Dishwasher rinse aids can help reduce water droplets' surface tension, allowing water to spread out in a thin, even layer and dry more effectively. Some rinse aids also contain ingredients to help prevent spotting and improve drying performance.
Select a Longer Drying Cycle: Some dishwashers have adjustable drying settings. Choosing a longer drying cycle can provide more time for plastic dishes to dry thoroughly.
Hand Dry if Necessary: If you find that plastic dishes are consistently wet after the dishwasher cycle, consider removing them a little earlier and towel-drying them manually to avoid water spots or marks.
Remember that plastic items are generally safe to use even when they come out of the dishwasher wet, as long as they have been adequately cleaned and sanitized during the wash cycle.