Read the instructions on most adhesives and contact cements and they require a layer on each part to be joined,often with a certain amount of drying time before joining.Call this one layer,two layers, or two half layers joined. The adhesive manufacturers use all the latest "science" in concocting their systems.Better living through chemistry! Let's not knock what we don't understand or call it myth. That's how religions are born. Art-a believer in science-Link,San Antonio,TX,USA