UVP X is a premixed salted collodion used for tintypes, ambrotypes, and glass negatives. It is formulated with two iodide salts and two bromide salts. It’s a cadmium-based formula that ages slowly, so you will have consistent results over a long period of time. Stored in a cool dark place, this collodion will maintain good working properties for 6-12 months.UVP X is specifically formulated with a slightly higher bromide ratio, which aids in achieving good tonal range in portraits. Also, it is easy to see the image during development, which helps achieve the most from the collodion. It’s the fastest of the super stable formulas (Lea Formula 3, UVP-4, UVP-X).