Other issues to watch out for when food, wax, etc. is attached to the part where there is no letters, numbers, etc.
Is There a Way to Strain Out a Drink That Is אסור מדרבנן (Asur M'drabanan/Rabbinically Not Allowed)?;
Addition to 1528: דבר דבר (Dabair Davar): הרהור Hirhurim (Thinking), Part 2;
fliptop, snap top caps, e.g. ketchup bottles, salad dressing bottles, etc.