This stain is used to distinguish collagen from muscle in tissue specimens using the Artisan™ Staining System. The Trichrome stain is often used to differentiate between collagen and smooth muscle and to identify an increase in collagenous tissue. With the Artisan™ Masson's Trichrome stain, muscle is stained red, collagen - blue, fibrin - pink, erythrocyte - red and nuclei - blue/black.