Insulated cups often have labels stating "hand wash only" or "not dishwasher safe" due to the following reasons:
Temperature and pressure: Dishwashers typically use hot water and higher pressure to clean dishes. Insulated cups are designed to maintain the temperature of their contents, whether hot or cold, for extended periods. The high temperatures and pressure in dishwashers can potentially compromise the insulation properties, causing the cups to lose their ability to effectively retain temperature.
Materials and construction: Insulated cups are often made of materials such as stainless steel, plastic, or glass, with multiple layers or vacuum insulation to create the insulating effect. These materials and constructions may not withstand the harsh conditions inside a dishwasher, leading to damage or deformations. For example, the extreme heat and rapid temperature changes in the dishwasher can cause warping, delamination of layers, or deterioration of seals.
Coatings and finishes: Some insulated cups have special coatings or finishes on the interior or exterior surfaces. These coatings may not be dishwasher-safe and could be damaged or altered when exposed to the high temperatures, detergents, or abrasion during dishwasher cycles.
If you ignore the "hand wash only" or "not dishwasher safe" instructions and run insulated cups through the dishwasher, several potential issues may arise:
Reduced insulation performance: The cups may lose their ability to retain hot or cold temperatures effectively. This can impact the duration for which the cups can keep beverages at the desired temperature.
Damage to materials: The heat, pressure, and detergents used in dishwashers can cause damage to the materials used in insulated cups. This may result in warping, discoloration, corrosion, or structural integrity issues.
Leaks or compromised seals: Insulated cups often have seals or gaskets to prevent leaks and maintain insulation. Dishwasher cycles may subject these seals to excessive heat or pressure, leading to potential leaks or a loss of their sealing effectiveness.
To maintain the performance and longevity of your insulated cups, it is generally recommended to follow the manufacturer's instructions and hand wash them as recommended. This will help preserve the insulation properties and ensure the cups remain in good condition for an extended period.