Is it normal for the inside of the stainless steel water cup to turn black?Can I still use it?

The editor received a message from a friend, a photo of the inside of the water cup, the question is can the stainless steel water cup still be used if it is black?

Because the photo quality is not very good, so I can't accurately judge what caused the internal blackening?Therefore, the editor analyzes whether such a water cup can continue to be used for some reasons that cause the black inside of the water cup.

If the stainless steel welding seam of the newly purchased water cup appears black, it is generally due to the failure of the laser welding process.The high temperature of laser welding will cause black spots to appear in the weld.Usually, the water cup will be polished during the production process, and there will be none after the polishing is complete, and then electrolysis is carried out.

If there is no problem with the material of such a water cup, it will not affect the use of 304 stainless steel or 316 stainless steel.If the material itself does not meet the standard, it is recommended not to use it.The specific way of judging whether the material is qualified has been mentioned many times in the previous article. Please read the previous article of the editor.

Just mentioned a process of electrolysis, electrolysis will also cause the inside of the water cup to turn black, that is, the inner pot is not bright.This is because the electrolysis time is not well controlled.If the electrolysis time is long, the old electrolyte will cause the inner tank of the water cup to turn black after electrolysis.But it is not a black spot, it is an overall blackening and darkening effect. This situation does not actually affect the use of the water cup, nor will it cause harm to the human body.

After using it for a period of time, if you are used to using a thermos cup to make tea, the inside of the water cup will quickly turn black, which does not affect the use.However, if you only use it for drinking water, and you find that there are black spots or black spots inside the water cup after a period of use, it means that there is a problem with the material of the water cup.After cleaning such a water cup, let it sit for a period of time, if there are still black spots, it must not be used, indicating that the material is not 304 stainless steel or 316 stainless steel.

In addition to the blackening phenomenon that occurs in the above situations, there is also the fact that it is not cleaned in time after use, especially after using a water cup with sugary drinks or dairy products, it will cause the appearance of internal mildew.In this case, if you can't do thorough sterilization and disinfection, editor also recommends not to continue to use it.