A liquid’s ability to seep through a product may be invisible to the naked eye, and can be desired or undesired. One example is medical tools designed to release dissolved antibiotics at a certain rate. Whether the leak is wanted or unwanted, it must be controlled. Achieving this requires deep insight in the structure of the product or material. One way to obtain that understanding is by neutron radiation, which operates much like a microscope that can see microscopic structures or even molecules. Such examinations may help prove a product’s efficiency over time, provide useful documentation and ultimately a reliable and durable product.