A permanent fixative is a spray or liquid that is used to preserve artwork created with dry media, such as charcoal, pastels, and graphite, by preventing smudging and fading. It creates a protective layer over the artwork, which helps maintain the integrity of the materials used and enhances the longevity of the finished piece. This is particularly important when working with charcoal, which can be easily smudged and is prone to fading over time.