Are cheap thermos cups necessarily of poor quality?

After the “deadly” thermos cups were exposed, the prices varied greatly. The cheap ones only cost tens of yuan, while the expensive ones cost up to thousands of yuan. Are cheap thermos cups necessarily of poor quality? Are expensive thermos cups subject to an IQ tax?

In 2018, CCTV exposed 19 kinds of “deadly” thermos cups on the market. After pouring hydrochloric acid into the thermos cup and leaving it for 24 hours, excessive amounts of manganese, nickel and chromium metals could be detected in the hydrochloric acid.

These three are heavy metals. Their excessive content may lead to low immunity, skin allergies, and induce cancer. They are especially harmful to the elderly and children, and may cause developmental dysplasia and neurasthenia.

The reason why the thermos cup contains these heavy metals is because its inner tank is generally made of three common stainless steel materials, namely 201, 304 and 316.

201 stainless steel is industrial stainless steel with relatively low chromium and nickel content. However, it is prone to rust in humid environments and is prone to corrosion when exposed to acidic substances, thus precipitating heavy metals. It cannot be in contact with food and drinks for a long time.

304 stainless steel is generally considered a food-grade material and can be used to make the liner of a thermos cup; 316 stainless steel is medical-grade stainless steel, which is more secure and especially corrosion-resistant.

In order to save costs, some unscrupulous traders often choose the cheapest 201 stainless steel as the inner liner of the thermos cup. Although such thermos cups are not easy to release heavy metals when filling hot water, they are easily damaged once they come into contact with acidic drinks and juices. Corrosion, resulting in excessive heavy metals.

Relevant national standards believe that a qualified thermos cup can be boiled in 4% acetic acid solution for 30 minutes and soaked for 24 hours, and the internal metal chromium migration amount does not exceed 0.4 mg/square decimeter. It can be seen that even low-quality thermos cups must meet the standards of being able to safely hold carbonated drinks, rather than allowing consumers to store only hot water.

However, those unqualified thermos cup liners on the market are either made of lower quality industrial-grade stainless steel, rusty stainless steel or used discarded steel, which will harm human health.

The key is that the prices of these thermos cups are not all cheap products. Some are more than ten or twenty yuan each, and some are as high as one or two hundred yuan. Generally speaking, 100 yuan is enough for businesses to use safe materials to produce thermos cups. Even if there are no special requirements for the insulation effect, tens of yuan can completely do it.

However, many thermos cups always emphasize their thermal insulation performance, giving consumers the illusion that their products are absolutely safe. When choosing a thermos cup on the market, we must pay attention and try to choose a slightly more well-known brand. However, there are thermos cups with SUS304 and SUS316 on the inner tank.

At the same time, you also need to observe whether there are signs of rust inside the thermos cup, whether the surface is smooth and translucent, whether there is any peculiar smell, etc. Generally speaking, the inner tank with no rust, smooth surface and no odor can basically guarantee that the material will not rust and it is newly produced stainless steel.

The prices of thermos cups currently on the market vary widely. Slightly cheaper thermos cups use tail evacuation technology and have a hidden tail chamber at the bottom for heat preservation, but they take up more space and reduce the water storage capacity.

More expensive thermos cups often remove this design. They generally use lighter and stronger austenitic stainless steel liner (belonging to SUS304 stainless steel). This kind of stainless steel controls the content of metallic chromium at 16%-26%, which can form a protective film of chromium trioxide on the surface and has strong corrosion resistance.

However, those thermos cups on the market that sell for more than 3,000 to 4,000 yuan each often have inner tanks made of titanium alloy. The insulation effect of this material is similar to that of stainless steel. The key is that it is very safe, because titanium does not cause heavy metal poisoning. However, this price is really not necessary for most people.

Generally speaking, most thermos cups are not considered IQ tax. This is the same as buying a pot at home. An iron pot that costs dozens of dollars a piece is not necessarily bad, but the probability of encountering low-quality products will increase. A very high priced product does not meet the needs of most people. Taken together, buying products priced at 100-200 yuan is the choice of many people.