Shop for Building Materials at The Home Depot. Henry 212 all purpose crystal clear sealant is a one-part, low cost, high-performance thermoplastic sealant. The cured sealant exhibits good physical properties including excellent adhesion to a variety of construction materials including marine surfaces. It possesses rubber-like characteristics and can be compressed or extended. Henry 212 all purpose crystal clear sealant is used in the construction field for sealing and adhesive applications. It is available in non-sag consistency for application by trowel or caulking gun in vertical and horizontal joints.