Do you know which kind of thermos is better suited for everyday use?

As one of the essential everyday items in people's work and daily lives, what exactly makes a thermos more suitable for regular use? Today, we'll explore this question from... Packaging Inspection Let's take a look from the perspective of everyday usability when it comes to thermos cups.

About the material of thermos cups

Currently, the inner linings of thermos cups are mostly made from stainless steel, which comes in various grades, including 201 stainless steel (industrial use), 304 stainless steel (food-grade), and 316 stainless steel (medical-grade), among others.

From Packaging Inspection Let's take a look: Stainless steel, formally known as stainless acid-resistant steel, comes in over 100 different types, each suited for distinct applications. Using the wrong type can lead to disastrous consequences! When it comes to food-grade stainless steel, we… Packaging Inspection The most commonly seen type is 304 stainless steel, with 201 and 316 also available. These three types of stainless steel are identified by numbers due to their differing compositions, yet all of them meet food-grade standards.

Choosing a stainless steel thermos is crucial.

304, a food-grade material, offers numerous advantages—so when shopping for a thermos mug, always aim for at least 304 as your minimum standard. Many mugs and other utensils even come with stamped markings on their packaging or inside, such as "SUS304" or "18/8," both of which are perfectly viable choices. While 304 stainless steel is easy to recognize, what exactly does "18/8" signify? Simply put, it’s an index ratio representing the proportion of chromium to nickel: 18 parts chromium for every 8 parts nickel—exactly the same ratio found in 304 stainless steel. On the other hand, when chromium and nickel are balanced at 18:10, you’re looking at the superior grade 316 stainless steel. However, 316 stainless steel is relatively rare in the market, largely because it comes with a significantly higher production cost! So, how do you actually choose the right thermos mug?

• Compare prices

You get what you pay for—when it comes to thermoses labeled with "304" or "316" materials but priced significantly below market value, buyers should stay extra vigilant. After all, nickel and chromium, the key ingredients used to produce "304" and "316" stainless steel, are relatively expensive. So if a product claims to be made from these high-quality materials yet retails at a bargain price, it’s worth double-checking whether it’s truly "real deal" or just a misleading claim.

• Check the label

In addition to comparing prices, when making a purchase, be sure to check the label—looking at the manufacturer, production standards, and usage precautions—to ensure the product isn’t a “three-nothing” item before using it with confidence.

• Touch it, smell it

When purchasing offline, customers can "feel" and "smell"—check if the inside and outside of the cup are smooth or rough, and sniff to see if the plastic or rubber components have any unusual odors.

How do you perform performance tests on a thermos?

How can we test the performance of a thermos? Let's start with Packaging Inspection From their extensive experience, the following two points have been distilled:

• Thermal insulation

Fill the thermos with hot water, tighten the lid, and let it sit for 2 or 3 minutes before touching the body and bottom of the cup. If it feels warm to the touch, the thermos isn’t doing a great job at retaining heat. Alternatively, you can pour hot water into the thermos and check how warm the water still is after leaving it overnight.

• Sealing performance

Fill the thermos with water, tightly screw on the lid, and then turn it upside down for a few minutes—or give it a vigorous shake. If no liquid leaks out, it means the cup has excellent sealing performance.

What are the safety risks associated with thermos cups?

In a thermos mug Packaging Inspection Meanwhile, some professional technicians have discovered that you shouldn’t judge the safety of thermos cups simply by looking at their packaging—many of these cups actually pose significant risks, so definitely avoid buying them!

• Heavy metals exceed the standard

The heavy metals mentioned here refer to those exceeding the standard in the inner lining of thermos cups. A qualified thermos cup, as we all know, is typically made from food-grade stainless steel with grades like 304 and 316. However, even stainless steel contains three key metals: nickel, chromium, and manganese. Generally speaking, manganese should be kept below 2%, chromium content should not exceed 18%, and nickel levels should fall within the range of 8% to 12%.

• Manganese Exceeds Standards

Metal contamination often occurs when some retailers, in an effort to cut costs, substitute manganese for other materials. However, excessive manganese levels can weaken the immune system, lead to loss of appetite, and may even impair cognitive function—and, critically, could increase the risk of cancer and Parkinson’s disease.

• Chromium exceeds the standard

Excessive chromium can damage the upper respiratory tract, causing rhinitis, pharyngitis, laryngitis, and bronchitis in the short term. Long-term exposure may lead to diseases such as squamous cell carcinoma, adenocarcinoma, and lung cancer.

• Nickel Exceeds Standards

Excessive nickel levels can easily lead to neurasthenia, systemic disorders, and reduced fertility, while also posing strong teratogenic and carcinogenic risks. Some low-quality thermos cups even contain harmful metals like mercury and lead, which can damage brain cells and result in intellectual disabilities in children.