A recent news article discusses "natural wine" made with grape juice fermented by native yeast, with nothing else added.
It is common practice to add sulfur in the form of sodium or potassium metabisulfite as a sterilizing agent and preservative. It is also common to add chemicals to raise (calcium carbonate) or lower (tartaric, malic, and/or citric acids) pH. Yeast nutrients (vitamins, ammonium dihydrogen phosphate), sugar, tannin, fining agents (egg white, dairy products, isinglass, pepsin, trypsin) and pectinase are also common additives.
What about flavorings or colorings, either natural or artificial? Some fruit-flavored wines are labeled "natural fruit flavor added." The referenced article suggests that artificial coloring is sometimes used. Given the great lengths that I go to to avoid artificial flavorings and dyes in my food, it would be distressing to learn they are present in wine.
Are wines sold in the US required to list additives on the label? Are American, French, or Italian wines permitted to contain artificial dyes or flavorings?