What process was used to create fresco paintings in a catacomb chambers?

Fresco paintings in catacomb chambers were created using the "buon fresco" technique, where pigments mixed with water were applied onto freshly laid wet plaster. As the plaster dried, it absorbed the pigments, creating a durable and vibrant image. This method required skilled artists to work quickly, as the plaster would set rapidly, necessitating precise application to achieve the desired detail and color. The cool, stable environment of catacombs helped preserve these artworks over time.