What material should be used to cover areas where smoke is entering the cabin due to an underfloor fire?

The use of wet materials to cover areas where smoke is entering the cabin during an underfloor fire is effective because wet materials can help to suppress smoke and prevent it from further infiltrating the cabin environment. The moisture in wet materials can absorb heat and suppress the movement of smoke by creating a barrier that can minimize smoke spread. This is particularly important in an aircraft scenario where protecting the cabin from smoke is crucial for the safety and comfort of passengers and crew.

In contrast to other materials, dry materials might not provide the necessary effectiveness in stopping smoke, as they can be ignitable or may not have the same capability to absorb heat. Plastic sheets are also inadequate, as they might catch fire themselves and do nothing to mitigate the smoke. Foam blankets, while useful for certain fires, may not specifically address the need to contain smoke from underfloor fires as effectively as wet materials.