A hand-painted dial is neither a photographic print nor a decal: it is paint applied directly onto the surface with miniature brushes, layer upon layer, often on supports no larger than two centimeters in diameter. The distinction matters because it changes everything — the response to light, the perceived depth, and the fact that no two pieces are identical.
Techniques vary radically depending on the support and the result sought. On porcelain — as with the Credor dials produced at the Micro Artist Studio — the indices are painted before firing in the kiln, then the piece returns to the artisan's hands for a second application in gold, then back into the kiln again. Heat stabilizes the pigments but introduces variables that cannot be completely controlled: this is why certain enameled dials require as many as twenty passes through the kiln, as happens with fondant de Genève, the traditional Genevan flux that is applied in successive layers and finished with a transparent coating that gives brilliance and protects the entire surface.
On standard metal dials the logic changes: here the artist works cold, layering color washes to build shadows and volume that at such a reduced scale are read almost only under magnification. Pointillism applied to dials — small dots of varying color and size, laid one by one — produces an effect that at normal viewing distance gives a uniform chromatic field, but under magnification reveals an almost textile structure. I have seen it applied on polished steel dials: it holds up surprisingly well over time if the piece is not exposed to humidity.
UV-reactive varnishes belong to a separate category: they are not visible in normal light and reveal additional details only under ultraviolet lamp. A recent technique, born in customization environments, with variable results in terms of long-term durability — on this I do not have sufficient data to speak with certainty.
The work on the Montblanc 1858 Geosphere — northern hemisphere hand-painted, approximately four hours per piece — gives an idea of the relationship between subject size and execution time. At those scales, four hours is very little. On complex enameled work, we are talking about days.
From the bench I often see dials presented as hand-painted that are actually prints with a final coat of varnish applied manually. The difference is noticeable: true painting has irregularities in thickness that catch light differently depending on the angle.