How are horizontal top gaskets assessed for watertightness?

The assessment of horizontal top gaskets for watertightness is primarily focused on their functional performance, particularly ensuring that they create a proper seal when the container is closed. This involves checking that the outer lips of the gasket are fully seated against the container's frame or structure, which prevents any water from leaking into the container. If the outer lips fit appropriately and do not leak light—meaning there are no visible gaps that would allow light to pass through—it indicates that the gasket is likely sealing effectively.

Assessing the gasket purely based on color and texture, visual inspection alone, or the material composition, such as being made from rubber only, does not provide sufficient information about its ability to function correctly in preventing water ingress. These considerations may help inform quality but do not directly relate to the critical evaluation of watertightness. Therefore, the emphasis on the proper seating and the absence of light leakage serves as a reliable method for determining the effectiveness of the gasket in providing a watertight seal.