The short version
A stainless steel thermos performs well when four things line up: a properly evacuated gap between two steel walls, a liner grade that suits what you pour into it, a lid and gasket that seal, and a heat-retention claim that states its test conditions. Most buyers check only the first. This guide shows how to check all four, using a real 200 ml specification as the worked example.
The vacuum flask was invented in 1892 by the Scottish chemist Sir James Dewar, originally to store liquefied gases. The principle has not changed. Heat moves in three ways, and a thermos blocks each one:
Because the insulation works in both directions, the same cup protects iced water in summer and tea in winter. In practice a thermos often holds cold longer than it holds heat, so a cup rated for "6 hours warm" will typically do at least as well with cold drinks.
Heat leaks where the design cannot be perfect: the lip where inner and outer walls are welded together, the lid and gasket, and any loss of vacuum over time. A quick home check helps. Fill the cup with hot water, wait five minutes, and feel the outer wall. A warm patch or condensation on the outside means the vacuum is compromised and the cup should be returned.
Model 6873 uses SUS316 for the inner liner and SUS304 for the outer shell. The split is deliberate. Only the liner touches your drink, so that is where the more corrosion-resistant alloy earns its cost.
The defining difference is molybdenum: 316 contains 2–3%, which markedly improves resistance to pitting and crevice corrosion in chloride-containing environments. A common comparison metric, the Pitting Resistance Equivalent Number, is roughly 19 for 304 and roughly 26 for 316. In everyday terms, that margin matters most when a liner holds salty broth, acidic juice, or a drink left in it for many hours. For plain water and coffee, 304 is also food-grade and perfectly adequate. The outer shell sees only air and hands, so 304 is a sensible, cost-efficient choice there.
Practical caution: a grade stamped on a spec sheet is a claim, not proof. Ask any supplier for a material test certificate for the steel coil. Also avoid soaking any stainless cup in chlorine bleach for long periods, since chloride is exactly what attacks the protective surface layer.
Model 6873 lists "6 hours ≥ 42 ℃". Read it carefully, because it reveals a lot:
Recognized standards fix those variables. India's BIS specification for vacuum flasks heats water to 95 °C and measures it at intervals of 1, 6, 12 and 24 hours. That standard draws on the European BS EN 12546-1 for vacuum ware. In China, GB/T 29606-2013 covers stainless steel vacuum cups, including requirements, test methods and inspection rules, and is listed as valid. When you evaluate a product, ask which method produced the number.
Pre-heat or pre-chill the cup with water for a few minutes before filling, and fill it close to the top. A fuller cup holds more thermal mass and leaves less air to exchange heat with.
| Specification | Listed value | What it means in practice |
|---|---|---|
| Capacity | 200 ml | A single serving; ideal for kids, short trips and sampling. Expect shorter hold times than larger bottles. |
| Inner liner | SUS316 | Molybdenum-bearing steel with better resistance to chloride and acid pitting where the drink makes contact. |
| Outer shell | SUS304 | Food-grade 18/8 type steel; strong, easy to form and suitable for painted or powder-coated finishes. |
| Lid / seal | PP lid, food-grade silicone seal | The lid is the main heat-loss and leak point. A silicone gasket is replaceable and does not hold odors easily. |
| Insulation | 6 hours ≥ 42 ℃ | Warm-drink performance. Request the test report for the filling temperature and room conditions. |
| Finish and branding | Spray painting or powder coating; logo; 3D printing or heat transfer | Powder coating generally gives more grip and scratch tolerance; bare steel is easiest to clean. |
| Minimum order | 3,000 pcs | A wholesale and private-label specification, not a single-unit retail item. |
| Listed uses | Commuting, campus, car travel, camping, office, home wellness, travel with young children | Versatile for day-to-day use; for hot soup or food, a wide-mouth food jar is a better fit. |
Source for listed values: the model 6873 product page.
Huading's own care guidance recommends washing before first use, hand washing afterward, and storing the cup with the lid off once it is dry. It also advises against abrasive scrubbers and harsh chemicals, and says not to microwave the cup. Two reasons make this worthwhile: dishwasher heat and strong detergents wear down gaskets and coatings, and a hard knock near the seam can dent the wall, so inspect the cup after a drop and repeat the outer-wall warmth check.
According to its company profile, Jiaxing Huading Vacuum Flask Technology Co., Ltd. was established in 2002 in the National Economic Development Zone of Pinghu, Zhejiang, and specializes in stainless steel containers. The site reports a 25,600 m² facility with 480 employees, and sales of 210 million RMB in 2025 with a 2026 target of 250 million RMB.
For private-label projects, the OEM/ODM service covers lid, color, logo, pattern and packaging customization. To discuss specifications and quantities, use the contact page.
It depends on capacity, fill level, lid, and starting temperature. Model 6873 lists at least 42 ℃ after six hours. Only compare hours between products tested under the same conditions.
It resists chloride and acid pitting better. Both are food-grade. The benefit shows most with salty, acidic or long-stored drinks.
Yes. Vacuum insulation slows heat flow in either direction, so iced drinks stay cold as well.
Hand washing is recommended and microwaving is not advised, as noted in the care guidance above.
The outside wall becomes warm to the touch or sweats when it holds a hot drink. Hot water in the cup for five minutes is enough to test it.
