The Hong Kong Consumer Council (CHOICE) has revealed significant discrepancies in the performance of popular travel mugs and insulated tumblers in a recent issue of its magazine, Choice (Issue 579). The comprehensive tests, conducted on 18 different models, assessed critical attributes like temperature retention, leak-proof design, and usability, finding major variations across the lineup, where even high-priced brands struggled in certain areas. This evaluation provides crucial information for environmentally conscious consumers seeking reliable drinkware for their daily coffee and beverage needs.
The Consumer Council sourced 18 travel mugs, ranging in price from approximately HK$80 to HK$425, from various outlets including coffee shops, department stores, and online retailers. These samples included 7 models with integrated straws and 11 conventional coffee or tumbler styles, all featuring covers with mechanisms like spouts, flip-tops, or sliding locks. The testing focused on how effectively these products maintain heat and cold, their ability to prevent leaks, and overall functional convenience.
Insulation Performance: Disparity in Temperature Retention
Thermal retention proved to be the most varied metric. Following a modified European standard (BS EN 12546-1) test method, samples were filled with near-boiling water (above 95°C) and monitored over six hours in a stable 20°C environment.
Only two models, NOC and STANLEY, excelled in heat retention, retaining temperatures above 60°C after six hours. The STANLEY model measured 63.8°C, while the compact NOC (354ml capacity) registered 60.8°C, demonstrating superior thermal efficiency for its smaller size. An additional six stainless steel models, including offerings from Starbucks and ZOJIRUSHI, maintained temperatures above 50°C.
Conversely, three plastic samples showed markedly poorer insulation, with water temperatures dropping significantly to between 26.3°C and 29.0°C over the testing period.
Cold retention tests, using chilled water (5±1°C), yielded slightly broader success. Eight samples, including models from STARBUCKS, DECATHLON, and WOKY, kept the water below 11°C for six hours, indicating strong performance for keeping iced beverages cool in Hong Kong’s humid climate.
Leakage and Stability Issues Highlight Design Flaws
For many commuters, portability relies heavily on a product’s leak-proof capabilities. The Council’s assessment involved two phases: immediate inversion and a more practical 45-degree tilt test. Encouragingly, twelve samples demonstrated excellent leak resistance, remaining dry after being held upside down for one hour. These high performers included brands like MUJI, Starbucks, and WOKY.
However, six models unfortunately failed the initial inversion test, exhibiting leakage. These included mugs from THERMOS, %ARABICA, and the temperature-retention star, STANLEY. While these leaking models passed the subsequent 45-degree tilt test, the initial failure raises concerns about complete liquid containment when tossed into a bag.
Furthermore, CHOICE highlighted a significant stability flaw in the high-capacity STANLEY (#15) tumbler. Due to its tapered shape, heavy handle, and high center of gravity, the cup easily lost balance and tipped over when placed on a minor 10-degree incline, whether empty or full, posing spillage risks during everyday use.
Material Safety and Capacity Accuracy
In terms of material safety, 15 stainless steel samples were tested for the release of 24 heavy metals, adhering to European standards (BS EN 13130-1). While trace amounts of metals like chromium, iron, and nickel were detected in some samples, the release levels remained well within safety guidelines established by the European Directorate for the Quality of Medicines & HealthCare (EDQM), posing minimal health risk under normal use.
The Council also flagged accuracy issues with labeled capacity. Fourteen samples were found to hold less liquid than their stated nominal capacity, with differences ranging up to 20.24%. Five brands—MUJI, 24BOTTLES, DECATHLON, NATIONAL GEOGRAPHIC, and PoleBear—exceeded the maximum allowable deviation of 10% outlined in European standards for insulated containers.
Consumer Takeaways and Safety Precautions
This vital testing underscores that cost and brand reputation do not always guarantee superior performance. Four models, all priced above HK$240, achieved the highest overall rating of 4.5 stars, balancing good insulation, leak resistance, and usability.
Consumers prioritizing heat retention should look for stainless steel and vacuum-insulated designs, such as the NOC and STANLEY models. Those concerned with leaks should stick to products like Starbucks, NOC, and WOKY, which performed well in containment tests.
The Council also issued a serious usage warning for all insulated containers: never store highly perishable food items, fermented ingredients (like medicinal herbs or red date water), or carbonated beverages inside thermos flasks. High temperatures can accelerate the growth of bacteria and cause fermentation, creating pressure that may lead to the lid “exploding” upon opening, posing severe injury risks. The report cited an incident where fermented red date water caused an eye injury when the lid burst off. Consumers should stick to housing plain water, coffee, or tea.