Barrier is a special and unique non-copal dentin tubule sealant. It is virtually inpenetrable by acids, water, monomers, and microorganisms. Barrier is biocompatable plastic material that forms an extremely thin film layer that adheres to dentin. Barrier is used to prevent post-operative discomfort caused by exposure to acid and irritants found in restoratives and cements, and by temperature changes in amalgam restorations.