Spiral wound and laminated using Sonoco\'s own recycled paper and adhesives for superior strength. Sonotube Void forms are engineered for use with cast-in-lace and pre-cast concrete. Interior and exterior surfaces are treated for protection against weather and moisture. Choose from plastic, metal, or wood end closures which can be pre-attached by Sonoco.For more information, please visit www.sonotube.com architecture, concrete, construction, contractor, forms, paper, sonoco, voids