After you have carved your seal and stamped an impression of it to see how it looks you may not be satisfied with the design. Before you decide to sand it down and start again you can try using some red and white paint—gouache works well for this as it dries quickly and is water soluble—to experiment with modifications. Stamp it several times on some paper and try different versions to see if you can improve it, then carve the changes and stamp it again to see how it comes out. Some critics might say that seal carving should be like calligraphy—you do it once with no corrections. They say this reveals the artist’s personality at that moment. I doubt they carve seals themselves as it’s not a very practical way to work with stone, which costs more than paper. Even famous seal artists of the past, like Qi Baishi who was famous for his direct technique, is known to have tweaked his designs.