An excellent quality masking medium in the pen is a product dedicated to watercolor paints. It's a thick, latex substance with a slight color. Effectively protects the surface (watercolor paper) against water and paint.
Renesans Intense Water watercolors have been tested for compliance with the highest quality standards in terms of stability, purity, solubility and light resistance.
Watercolor block with natural white 100% cotton watercolor paper. The block has 10 sheets of cold-pressed paper with a weight of 300 grams. Glued on the short side with a stiff cardboard on the back.