In the production of vinyl fencing, co-extrusion refers to a process where two or more layers of vinyl material are extruded simultaneously. This process allows for the creation of fence profiles with multiple layers of vinyl, each with their own unique properties and characteristics. The outer layer of the fence profile is typically a high-quality, UV-resistant vinyl that helps to protect the fence against fading and discoloration. The inner layers may be made of a different type of vinyl that is more flexible or has other desired properties. Co-extrusion can be used to create a variety of fence styles and configurations, and is often used to improve the durability, performance, and appearance of vinyl fencing products.
Co-Extrusion is a more recent advancement in extrusion technology which brings 2 layers of PVC into play: The outer layer, or Cap Stock, contains a denser concentration of UV inhibitors. ASTM’s “Specification for Rigid PVC Exterior Profiles Used for Fencing” (F 964-94) requires that the cap stock layer be a minimum of 00.015” thick and a maximum of 20% of the overall thickness of the profile wall. It is important for the potential buyer of a Vinyl fence to determine what ASTM specification is being used by his potential extrusion supplier, if in fact any is being used at all, and to ensure that compliance is being verified regularly.
The inner layer, or Substrate layer, when produced with virgin raw materials, is essentially the same as the cap stock layer, but with a lowered concentration of UV inhibitors and color pigment.