Blistering on a varnished surface can occur if the varnish is applied in too thick a layer or if the substrate is not sufficiently clean or dry. The solution is to remove the bubbled layer, prepare the surface properly and reapply the varnish. Make sure you apply the polish thinly and allow it to dry properly. If you need help, turn to a professional who can ensure a smooth and even finish. Send a quick quote to find the best specialists in your field.