The ripples on Damascus blades weren't decoration, they were the steel's insides

This steel made legendary blades, but forge it like normal iron, too hot and too hard, and it could crack in seconds. The famous watery ripples on Damascus blades were never painted on. They grew from inside the steel. Southern Indian smiths melted iron in sealed clay crucibles to make wootz, about 1.5% carbon. The fix was the opposite of instinct: dozens of cooler heat-and-hammer cycles, until carbide bands lined up and showed through as ripples. By the 1800s the craft was lost. In the 1980s researchers found the missing clue: vanadium, just four parts in a hundred thousand. Sources: • Verhoeven, Pendray & Dauksch, The key role of impurities in ancient Damascus steel blades (JOM, 1998) · http://dtrinkle.matse.illinois.edu/MatSE584/articles/key_role_impurities/key_role.html • Verhoeven, Damascus steel, Part I: Indian wootz steel (2007) · https://www.tf.uni-kiel.de/matwis/amat/iss/kap_a/articles/verhoeven_2007.pdf