Solution A: Neutral Red Stain 1%, Alcoholic 500 ml, Solution B: Fast Green Stain 1%, Alcoholic 200 ml. Newcomer Supply Twort’s Gram Stain Set provides stain solutions for the Gram Stain, Hucker-Twort, a simple, rapid procedure for staining gram-positive and gram-negative bacteria without picric acid. The Twort Stain combines Neutral Red and Fast Green, for clear detection of red gram-negative bacteria with a green counterstain. Shelf Life is 2 years from date of manufacture. Store at 15-30°C.