The ECRINAL® Bitter Varnish is completely invisible and prevents nail biting and contouring, due to its extremely bitter taste. This varnish facilitates the renewal of the nail. It can be used in children from 3 years old, to help stop sucking on the finger. Application advice:. Apply to the nails at least twice a week. Do not use in children under 3 years. To remove the bitter varnish, use an alcohol swab.