My favorite lacquer to coat my patina work. It is made for band instruments so it works great on silver, copper and bronze. It is non toxic when dry. Most lacquers have a  yellow tint but Nikolas is water clear. It is super thin and you cannot even tell it is on. Even if it coats a gemstone the gemstone facets still shine and sparkle. The trick to using it on patinas is to spray a minimum of 18" away and give three very light coatings allowing it to dry in between coatings. It dries pretty quickly in one to two minutes. After a few coats you can go in closer for a final coat.