Enamel is a semi-transparent, or opaque material used for decorative purposes on glass , pottery, and metals . Discovered by the ancient Egyptians around the year 21000 BC, this art reached its climax in Spain in the 12th century, especially using the Champlevé method, and it was widely used during the Renaissance in the jewelry industry . Enamel is composed of sodium or potassium borate , lead and some silicates , and mineral oxide is added to obtain the desired color. Distribute liquid or dry to the surfaces to be painted, then leave a certain period inside the oven.