... yellow gum rosin ww grade sample is available Gum rosin also called colophony, is a solid form of resin obtained from ... room temperature rosin is brittle, but it melts at stove-top temperatures. It chiefly consists of different resin acids, especially ... of synthetic rubber and printing ink, resin acid is changed into disproportionate rosin, polymerized rosin, hydrogenated rosin, for further use by its ...