I love the Uart range of sanded pastel papers as they offer me the widest range of surfaces available.  Although i do love coloured supports, whenever I want to make up my own colour underpainting, I use Uart, and there’s still plenty of tooth left to grip the pastels, whether i use acrylic, oil or watercolours for my base colour. I use the entire range, from smoothest to roughest depending on the subject I am painting – a great product!!