The watercolor technique hard and soft edges is a process of applying watercolor by blending a sharp edge into a blurred edge to make it appear to fade softly into the distance for depicting perspective and/or for forming three-dimensional shapes.
Hard, sharp edges are best achieved using the wet-on-dry technique.
Painting hard edges can be achieved by using the tip of the brush to paint a line on dry paper. Then continue to paint in the shape of the object being painted.
For more control, masking fluid, masking film, or masking tape can be applied to the edges of the object to be painted. If using masking fluid, wait for it to dry completely. Then paint within the shape that has been masked off. After the painted area has dried, remove the masking.
Hard edges can also be formed by pushing pigment to the outside of a shape by first painting the shape then dropping clear water from the tip of a brush into the center of the shape. This will push the paint pigments to the outer edge of the painted shape forming a hard edge.
Soft, blurred edges are best achieved using the wet-on-wet technique.
Painting soft edges can be achieved by brushing watercolor onto paper previously wetted with water. The edges of the painted area will spread outward causing a soft, blurred edge of color.
Soft edges can also be achieved by adding water to a clean brush and painting over a hard edge before the edge has dried. This method is used for fading a color to a lighter value in blending and molding shapes such as folds in fabric, depicting light and shadow reflected on forms, etc.