Gianluca, the Saratoga product is definitely something you do not want to use. It is an exterior water repellent for masonry similar to Thompsons water seal. you actually do not need to use this before you use a varnish. when the piece is dry or cured, place the case in a box with a lid and put a box of baking soda in it. it will absorb the smell. you can leave it out side (warm day) for few days and it should go away as well. The more circulation of air will remove it faster. What capsules did you use. I would love to hear how your melodica sound.