To obtain a smooth surface with as invisible brushstrokes as possible on smooth surfaces, e.g. panels, doors, smooth metal surfaces: use semi-gloss finishing paint. Apply the paint in one direction to obtain an opaque and, if possible, even layer of paint. Cross stroke without taking more paint on the brush, i.e. stroke in a perpendicular direction to even out the paint. Smooth the surface by using a feathery hand to move the brush in the same direction as you applied the paint. If you apply too thickly, it will be difficult to smooth out the brushstrokes. Video: interior painting with linseed oil paint. Follow the instructions on the GENERAL page above.