What does thick, oily soot on glass typically indicate?

Thick, oily soot on glass is typically associated with incomplete combustion of materials. When combustion occurs, it ideally requires sufficient oxygen to convert fuel into carbon dioxide and water. However, when there is insufficient oxygen or when the fuel source has a high moisture content or other complicating factors, the result is incomplete combustion. This process generates large amounts of particulates, including thick, sticky soot that can adhere to surfaces like glass.

The presence of this type of soot can indicate that the fire did not achieve its optimal burning conditions, which often leads to higher levels of harmful products of combustion such as carbon monoxide and particulate matter. This characteristic is a key observation for fire investigators in determining the nature of the fire and its possible causes. It points to potential issues with the fuel being burned or the airflow during combustion, which are critical components in fire dynamics.