What is fixative?
Any of a variety of transparent materials that, when applied to artwork, keeps the medium (paint, ink, pastel, etc.) from smudging. While the most common fixative in mixed media art is a spray acrylic that comes in matte and gloss versions, other kinds of fixatives include varnish, shellac or resin diluted with alcohol.
This is most commonly used by fine artists, but it is also useful for smear-prone mediums, such as pastel, charcoal and graphite.
However, any additional chemicals will affect your art, and it is not recommended for watercolor artwork.