While Walter’s primary medium was the woodcut, like many artists, painting - for which he first won the John Wanamaker Gold Medal in a city-wide art competition in New York City at the age of 12 - was his first medium. Watercolors in particular afforded Ferro a relief from the laborious processes involved in woodcutting and engraving, as well as the freedom to use color spontaneously. As with his other work, he employed variably both realism and abstraction. Intricately attending to the details of an awning at dawn, the vertical lines on the side of a barn, or a rough stone wall bordered by snow, many of his landscape, village, and agricultural scenes remain those for which he was best known. Still, in the abstracted works there reside an equally fervid use of bold color, which with the introduction of additional water he even allowed at times to run or smudge, a liberality not proffered in the assiduousness of his woodcut process.