What is a Lake?
According to the FDA, lakes are formed by reacting straight dyes (such as FD&C Green No. 3) with precipitants and salts. Aluminum is often a component. Lakes may be used as color additives for tablet coatings due to their stability, and may also be used for cosmetics such as eye shadows. Its use in coloring foods, pharmaceuticals and cosmetics may be of quantities allowable by the U.S. FDA. Because lakes are not soluble in water, they often are used when it is important to keep a color from "bleeding," as in lipstick. In some cases, special restrictions apply to their use.
Referenced from: https://www.drugs.com/inactive/aluminum-lake-dyes-332.html