Fluorescein, C20H12O5, is an organic dye which when dissolved becomes extremely fluorescent under UV light. This dye is used in leak detecting and fluid tracing, as well as in highlighting markers and fluorescent toys. In small quantities it is non-toxic, and is even used to find micro fissures in eye surgery, however it is not food-safe and should never be used in contact with skin or internally. For detection, our UV Flashlights can't be beat.Sold in 6cc or 15cc dropper bottles. Recommended concentration for oil and water dyes is 16 drops per gallon of fluid to be dyed, so the 6cc bottles can dye up to 8 gallons, the 15cc bottles up to 20. Please note, unless it's dissolved, it appears a red/orange color and IS NOT fluorescent. It needs to be dissolved in it's intended solvent to appear green. The AC refrigerant dye is a PAG 100 compressor lubricant as well as a dye, optimized for most automotive and stand-alone residential systems using R-134a or R-12. Usage is 5-10 drops for a typical automotive system, but consult your unit's manual for specific lubrication needs. NOTE: Air conditioning systems are complex in their operation and repair, and contain chemicals that are hazardous to your health and the environment. Do not attempt repairs without having thorough knowledge of the entire system before you begin. All dyes have manufacturer certification available on request, excepting the Craft-grade dye, which shouldn't be used in expensive, critical, or food-grade machinery, but is plenty of fun for other projects, or non-critical leak and flow testing in water systems. As always, Vadien is dedicated primarily to promoting scientific endeavors and education through parts or supplies in the quantity and quality you need. Let us know if you have any questions, or if you're having trouble finding the right part or material for your project, we're always glad to help with parts or advice!