The top coat and base coat together sandwich the design in, protecting it from both sides. When the top coat is dry any overspray on the fingers can be washed off with water.
Before applying top coat, use your airbrush to lightly mist on layers of Medea Nail-Art Sealer Varnish over your design so that it dries quickly. This will seal your design and protect it from the brush strokes when you apply the final top coat.