UVP 3 is a fast salted collodion that comes either premixed or as a two part. It is a cadmium free formula that can be used for tintypes, ambrotypes, and glass negatives. It is formulated with one iodide salt and one bromide salt. It’s a lithium-based formula that ages quickly, so it is best to use the mixed collodion within 4 to 6 weeks. This can be prolonged with cool dark storage. When using the two-part, it will ripen and be ready to use within hours. This way you can mix only as much as you will use.