Which type of soot residue can appear greasy and may be brown or yellow in color?

Protein residue, which is a byproduct of cooking and the burning of food materials, can indeed appear greasy and may take on a brown or yellow color. This type of soot is typically derived from materials that release proteins when burned, such as meat or other organic substances.

The greasy appearance is significant because it affects how cleaning agents need to be applied; specialized techniques or solvents may be required to effectively remove this type of residue from surfaces, especially porous ones like carpet or upholstery. Additionally, protein residues can be particularly challenging to clean if they are not addressed promptly, as they may bond more strongly to surfaces over time. Understanding the characteristics of protein residue assists technicians in choosing the appropriate cleaning methods to restore affected areas effectively.

Other types of residues, such as water-soluble residues, are easier to clean and typically do not have the greasy characteristics associated with protein. Soot from natural gas and plastic or rubber residues also do not typically exhibit the same greasy appearance or coloration that is indicative of protein residue.