Crimtane Bars are the alternate version of Demonite Bars as of 1.2. They are the refined form of Crimtane Ore, which can only be found if the world has the Crimson instead of the Corruption. Each bar requires 4 Crimtane Ore, and a Furnace is required to craft them. Its counterpart is Demonite Bars if the world has the Corruption instead of the Crimson.
Items crafted from Crimtane deal more damage per hit than their Demonite counterparts, but are generally slower.