They are all stainless steel water cups. Why do some of them turn black after using for a period of time? Some will not turn black?

Why do some of them turn black after using for a period of time? Regarding the problem that the stainless steel water cup will turn black after being used for a period of time, we need to talk about it from several aspects:

1.The reason for the material.

The same stainless steel water cup, due to the different materials used, will cause the inside to become black after a period of use. For example, comparing 304 stainless steel with 201 stainless steel, 201 stainless steel will turn black inside after a period of use. At the same time, the blackening inside the stainless steel water cup is mostly caused by the material.

2.The internal processing technology is different.

The same is a stainless steel water cup. Some water cups are electrolytically treated, and some water cups are sandblasted on the internal surface, which is equivalent to forming a protective layer on the internal surface. And some stainless steel water cups are polished inside, and no protective layer is formed. Similarly, if you drink acid-alkaline liquids for a long time, the inside of only the polished treatment will appear black.

3.It is related to personal living habits

For example, some consumers are accustomed to drinking carbonated beverages, tea, or using stainless steel water cups to make coffee. Consumers who often drink these beverages should clean and maintain the cups in time. Carbonated beverages will be corroded when kept in stainless steel cups for a long time, and the tea itself will have the precipitation of tea stains. Because coffee has strong vegetable oils, pigmentation can also be formed if it cannot be cleaned up in time.

Therefore, there are many reasons for the internal blackening of stainless steel water cups after a period of use, but most of them are caused by materials that do not meet the standards. If you find that the inside of the stainless steel water cup is black in daily use, you can first use a magnet to adsorb the inner wall to determine whether the material is not up to standard. Once it is found that the magnet can be adsorbed on the inner wall of the stainless steel water cup, it means that the material is not food grade material, please do not continue to use it.

The thermos cup produced by Dongguan Zhanyi Commodity Technology Co., Ltd. uses sufficient materials and exquisite workmanship. In terms of material, we insist on using food-grade 304 stainless steel inside and outside, or a combination of 304 stainless steel outside and 316 stainless steel. The heat preservation time can reach 8 hours, and the cold preservation time can reach 12 hours. We insist on using the AQL1.0 inspection standard, which is far higher than the peer standards, and all links adopt a full inspection system to ensure that each product is a high-quality product. Customers from all over the world are welcome to visit our factory for inspection, and welcome to place orders for cooperation.