I use a combination of carving tools, small rifflers of various shape, and various scrapers, as well as various sanding blocks, various shapes. In the gessoing process, edges get soft, lines get filled. The French make tools specifically for the carving of gesso, usually in conjunction with carving in general ... me, I just use what I have, the small carving tools, scrapers and rifflers.
(riffler |ˈriflər| noun
a narrow elongated tool with a curved file surface at each end, used in filing concave surfaces.ORIGIN late 18th cent.: from French rifloir, from Old French rifler ‘to scrape.’
It's those French again. Wonderful place, France; I've been fortunate to spend a few weeks in France, both Paris and La France Profond, the country side, Provence actually. Waiters still sneer at my French, but I do get what I ordered. I take that as a great compliment. Any place that has as much variety in wine and cheese, and also has restaurants devoted to nothing more than "snails", Escargot ( Snails, broiled in a combination of butter, garlic, and parsley, in the shell) ... well, that is a good thing. In the photo below, please note that the snail is gilt. One of those "small" regrets, is that I didn't find this restaurant until we were leaving, and that was on a Sunday, and France, being Catholic; many businesses are closed. There are regional variations in the recipe; after all, it is France.
Mean while, back at the ranch, where the bleeding, split fingers are. In the winter, the back and forth and pressure of sanding tends to aggravate the skin splitting.
Any way, the idea is to clean, refine and smooth the edges and surfaces.To make edges crisp, and everything ready for the bole.