From a New York Times obit by Joseph Berger headlined “Adolfo Kaminsky Dies at 97; His Forgeries Saved Thousands of Jews”:

Adolfo Kaminsky’s talent was as banal as could be: He knew how to remove supposedly indelible blue ink from paper. But it was a skill that helped save the lives of thousands of Jews in France during World War II.

He had learned how to remove such stains as a teenager working for a clothes dyer and dry cleaner in his Normandy town. When he joined the anti-Nazi resistance at 18, his expertise enabled him to erase Jewish-sounding names like Abraham or Isaac that were officially inscribed on French ID and food ration cards, and substitute them with typically gentile-sounding ones.