Where There’s Smoke There’s A Lot More Than Meets The Eye
Types of smoke vary as much as the fires that produce them. A clear understanding of how smoke is created and what it contains is vital to smoke restoration technicians and insurance professionals.
Here’s an example.
Monday morning, an insured calls about an accident during the weekend. Absorbed in the big game Sunday afternoon, a pan of chicken was left frying a little too long. By the time the homeowners notice the smoke, the flames have set fire to the cabinets; attempts to extinguish the flames with water only make the situation worse. Finally, remembering the extinguisher in the washroom, the fire is put out.
Unfortunately, the damage has already been done. Now it’s up to the adjuster and the restoration contractor to decide what can be restored and what should be replaced.
At first glance, many surfaces that appear only lightly affected may require more specialized treatment to remedy or may be beyond recovery. On the other hand, materials seemingly beyond repair may be salvageable, if proper techniques are used.
In both cases, a full understanding of smoke is essential: The different types; how they are produced; what they are comprised of; and the remediation options available in each instance.
Types of smoke
The size, quantity and character of the smoke particles and aerosols produced by a fire depend on the nature of the material burned, the rate of combustion and the combustion time.
Fires are frequently categorized by the rate of combustion, which depends on the amount of oxygen available. In the restoration industry, smoke is categorized as either “wet” or “dry.”
While every fire progresses through several stages, generating both types of smoke, the proportions often vary enough to characterize an entire exposure as predominately “wet” or “dry.”
Smoke referred to as “wet” comes from slow-burning, oxygen-starved fires, and is made up of larger particles. This type of smoke typically contains a high proportion of aerosols containing varnishes, solvents or other liquid components. As a result, “wet” smoke frequently leaves an oily residue.
“Dry” smoke comes from fast-burning, oxygen-rich fires. These faster-burning fires lead to more complete oxidation of the materials burned, creating much smaller smoke particles.
The materials consumed also influence the type of particles and aerosols produced by fire. Dry wood, paper and natural fibers tend to produce a small, non-smeary residue. Plastics, foam, rubber and similar polymers produce large, easily smeared residues.
While these major fire categories are distinguished by characteristics of the combustion process, their significance lies in the different techniques that must be applied in order to remove the smoke.
Some smoke damage is not economically feasible to remediate.
Another type may be removed, but only from certain materials.
Removal of some smoke residue is slow and costly; other types are more easily removed with a correspondingly lower cost. The ability of a restoration professional to distinguish between the two types is vital to insurance professionals and homeowners alike.
There are a number of different types of residue. These residues are produced by the circumstances that tend to accompany a particular kind of fire.
The major categories are listed below.
Each type produces its own unique residue, which requires a particular procedure designed for that purpose.
Wet smoke residue
Residue from smoldering, cool or oxygen-starved fires is some of the most difficult to remedy. It is slow-burning and is not driven by strong convection currents from the heat of the fire. Wet smoke moves slowly and has time to work its way into crevices and enclosed areas that normally would not be contaminated by a faster burning fire.
The incomplete combustion releases solvents, varnishes and other aerosols, which can soften, penetrate and stain finished surfaces.
Unfinished wood and fabrics may absorb these residues and entrap them. Removal of this type of residue may not be possible and stripping and refinishing of furniture may also be inadequate.
Buildings affected by wet smoke may require replacement of walls, floors and appliances, which in other fires would be restorable by cleaning or painting.
Typically, more demolition is required to expose enclosed smoke pockets. Where removal is possible by cleaning, it may exceed normal production time by a factor of four or more.
Dry smoke residue
Smoke from oxygen-rich, fast-burning, hot fires tends to carry few aerosols and deposits small particles that do not smear easily.
Dry smoke does not stain surfaces as deeply as wet smoke. Less aggressive cleaning procedures are required, permitting successful restoration of a wider range of materials. Labor costs are correspondingly lower.
Plastic or rubber smoke residue
Plastics, synthetic-rubber and other polymers tend to burn vigorously at low temperatures, producing a large, lightweight particulate that smears easily.
A small quantity of plastic can produce a surprisingly large volume of smoke that can travel large distances and tends to deposit in heavy concentrations.
Because of the high chlorine component of plastics, smoke from plastic fires can be highly corrosive to metal parts and exposed chrome trims.
Plastic particulates readily connect in chains, forming heavy “smoke webs” at ceiling corners and hanging fixtures as a result of a high degree of ionization. The tendency to smear easily requires care in the removal of smoke residue created by plastics, particularly from fabrics, wall coverings and other textured surfaces.
Pre-treatment to prevent further damage is often needed.
The smell of burned foam rubber can be extremely noxious and may render living areas uninhabitable until the odor and its source have been removed.
Most kitchen fires involve cabinets, counters and walls, generating the characteristic particulates for those materials. However, meat or poultry is sometimes overcooked in an oven or stovetop to the point where only a bit of charcoal remains.
The protein residue from such a source may be invisible; however, an extremely pungent odor is deposited with discoloration of painted wall and cabinet surfaces. Because of its persistent nature, removal of protein discoloration and odor can be extremely difficult.
Fuel oil residue
Soot from malfunctioning oil burners varies widely in its appearance and consistency, depending on the nature of the disorder.
Puff-backs are composed primarily of old soot jarred loose by the impact of a sudden ignition; however, prior to that ignition, the furnace may have been emitting smoke over an extended period of time. When the problem continues for more than one heating season, the soot may bond to wall paints, resulting in paint removal along with the residue during cleaning.
At other times, fresh soot may be readily removed with the appropriate techniques. Because of its ready distribution through the air system, soot can spread evenly throughout a building, sometimes escaping detection until a particular event brings it to light. The residue varies in color from gray to black and particulate size from extremely small to large.
Education Equals Better Restoration
Because different types of smoke can behave in different ways, a complete understanding of how it was produced, what it is made up of and the restoration options available is vital when deciding when to replace or remediate damaged materials.
While the information above is a good start, speaking with a fire damage restoration professional familiar with these techniques is always recommended.
Fire restoration can be quite complicated. It’s important to have an experienced restoration Expert on your side. An immediate treatment will help reduce health hazards and simplify any additional cleanup.