Lea Formula 3 is a premixed salted collodion used for tintypes, ambrotypes, and glass negatives. It is formulated with one iodide salt and one bromide salt. It’s a cadmium-based formula that ages very 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 12 months or more. Lea Formula 3 takes time to ripen and is ripe and ready to shoot when shipped. This collodion is great for people who shoot on and off and don’t’ want to plan ahead to mix collodion the day before. It’s stable and ready to shoot.