Q. Is there a way to check if the bottle is properly keeping warm (or cold)?"

After pouring boiling water, touch the lower side of the bottle after about 5 minutes. If the body feels warm, it means the insulation is no longer effective, so please stop using it.

Q. It no longer keeps warm (or cold). Why is that?

The vacuum insulation structure of the body may have been compromised.

Q. The inside of my stainless steel cookware has discolored to a rainbow color.

This phenomenon occurs when ions, iron, and copper in the water adhere to the surface due to evaporation, causing a rainbow-like appearance. It is more likely to occur in relatively new conditions, and the product itself has not discolored (deteriorated), so please use it with confidence.

Q. No matter how many times I wipe it, black stains keep appearing. What is this?

Two things can be considered: 1. If you rub the "oxide film" on the stainless steel surface too hard, black stains may appear, but there is no hygiene problem. 2. It may be stainless steel particles left from the polishing process. Please wash it thoroughly with dishwashing detergent.

Q. Please tell me how to season the oil.

"Seasoning the oil" means applying oil to the surface of the iron to create a thin film that makes it less likely to stick. When you first start using it, the oil is not sufficiently seasoned, so it is recommended to thoroughly perform the "seasoning the oil" process.