Update: We've tested two new techniques for dyeing glass jars. Check them out here!
Remember the Mod Podge + food coloring technique for painting clear glass? That was cool and all, but I spotted another method using Vitrail glass paint and acetone (nail polish remover) that allows the bottles and jars to be used as actual vases, as the finish is waterproof! This treatment provides for more depth of color as well.