Can a cloudy day make a blue sun?

This drying method can be carried out on cloudy days.

Blue exposure is the first classic non-silver salt photography process, which can be very simple and take successful photos in a short time. In the drying process, it is necessary to spread the plants on the surface, cover them with transparent acrylic board, move them to a place with strong ultraviolet rays, and dry them for about 15 minutes. If it is cloudy or cloudy, dry it for 20-30 minutes on cloudy days. With the end of the drying time, the blue color of the photo slowly appears.