Some of the colors didn't adhere to the intonaco layer. The lime / sand mixture was 40-60, and though it took a long time for the layer to dry and lay my traced pounce drawing on the surface ( about 2 hours! ), I finally was able to do so and begin painting. I first tried to lay in some of the shadows and darks with transparent earth colors ( umbers, bohemian green earth ) etc., but some of them didn't carbonize and after two days of drying, the pigment flaked off when rubbed lightly with my finger, especially the browns. Some colors 'took' ok, the more dye-like pigments, but the chaulkier ones just seemed to dry on top. I don't think that the lime surface had "locked up" yet, so something else happened. Anyway, when I sprayed the dry painting with a garden hose, all the pigments peeled away. This has been a great setback for me, after months of research, materials gathering, expense, etc. A failed painting doesn't bother me so much, but a failed process stops me cold; I don't know how to go on and do it right.