Manicare Nail Hardener nail therapy. Toughen up and grow your nails with this protective hardening formula. Description Manicare Intensive Nail Hardener. Intensive 14 day Nail Hardening Solution. For soft, weak nails. Indications - Longer, stronger, healthier nails. - Super-bonds instantly to soft, thin, weak nails. - Creates a strong protective shield that helps the nail grow longer and stronger. - Seals edges of nails for added protection and resistance against tearing. - Can also be used as a base coat with coloured nail enamel.