What is a Stress Skin Panel in Wastewater Structure Coating? We regularly refer to the OBIC Armor three-layer system for wastewater structures as a stress skin panel.  During a recent conversation with a public works director, he asked for a more thorough explanation.  A brief summary of that explanation around what a stress skin panel in wastewater structure coating is follows, and we're sure there are more people who would benefit from this information as well! The OBIC Armor liner system is a sandwich-structured composite.  It consists of an inner and outer layer of flexible polyurea with an inner core of hybrid polyurethane.  Sandwich panels exhibit great strength, which is why they are commonly used in airplane construction, vehicle fabrication, and building construction. Let's take a closer look at sandwich panels.  The inner and outer layers are referred to as "skins" and the inner material is the