Proline Decorative Concrete Systems Dura-Stain PS320 1 gal Oak Reactive Acid Stain for Concrete. Proline Dura-Stain is a chemical reactive stain developed to permanently transform ordinary concrete surfaces into the beautiful, variegated look of polished stone. It is available in the widest array of natural colors possible in a mineral-based reactive stain, giving the applicator a solid, earthy palette to work from. Reactive stains are water based stains made with a weak solution of acid and minerals that react with the free lime available in the surface of fully cured concrete. The effect is a variegated, marbleized finish that uses the imperfections in a concrete surface rather than covers them up. It is possible to achieve even more interesting shades and colors by -Stain over concrete surfaces colored with Proline Color Hardener and Antique Release Agent. Plus, create a dazzling combination of effects with stampable impressions and Dura-Stain Reactive Stain using Proline stamps and tools.