Think Like A Proton And Stay Positive Science T-Shirt Solid colors: 100% Cotton; Heather Grey: 90% Cotton, 10% Polyester; All Other Heathers: 50% Cotton, 50% Polyester Imported Machine wash cold with like colors, dry low heat Science shirt for someone who want's proton shirt, proton, Science shirt or nerdy shirt funny science t-shirts, this novelty tee shirt for the chemist in your life or for anyone really. Lightweight, Classic fit, Double-needle sleeve and bottom hem