Acme Face Creams produces high-priced night creams. The creams consist primarily of natural substances, but one ingredient can result in an allergic reaction in a small minority of users. The product must be packaged in glass, as its properties can become unstable when in contact with plastic. Designers have created a smoky (opaque) navy blue pot with a plastic rim inside the lid.
What must Acme consider in designing its labels for this product? What should the labels show?