Restoration technicians should be familiar with the basic chemistry and principles of cleaning.

These principles are the science that makes the cleaning process work and will help technicians avoid or solve problems when restoring smoke-damaged building materials.

Cleaning principles

Cleaning principles are generally categorized into six categories:

  1. Solvent action
  2. Chemical reaction
  3. Lubrication
  4. Agitation
  5. Temperature
  6. Dwell time of the solution.

Solvent action

Most smoke residues are acidic. Therefore, most water-based cleaning products used in fire restoration are alkaline. Alkaline products have a pH between seven and fourteen. Solutions that have a pH of less than seven are acidic. The farther away from seven, or neutral, the product’s pH is, the more aggressive cleaning the product can provide.

Acidity, as well as alkalinity is often described in terms of the pH, which is a measurement of the concentration of hydrogen ions in a water-based solution. Pure deionized water has a pH of 7.0, and other solutions are usually described with reference to this value. Acids are defined as those solutions that have a pH less than 7 (i.e., more hydrogen ions than plain water); while alkaline solutions (or bases) are defined as those solutions that have a pH greater than 7 (i.e., fewer hydrogen ions than plain water).

Chemical reaction

Rust spots on carpet are corrected by use of this method for example. In this case, an acid combines with the oxidized metallic residue and the resulting material is rinsed away.


Reducing friction between the surface and smoke residue. By reducing the friction between these two surfaces, the residue can be removed easily without causing scratching to the surface finish. Vegetable oil soap is a common lubricant cleaner. This method is commonly used on finished wood surfaces that will not be damaged by water.


Utilizing some type of physical force to suspend soot residue. Agitation media range from least aggressive to most aggressive. The most frequent method of applying water-based cleaning agents is with a soft towel. A different cleaning result will be achieved if the same solution was applied with a brush. The level of soot contamination should determine the proper level of agitation, the cleaning agent used and the surface involved.


Higher temperatures speed chemical reactions, open surface pores on the finish being cleaned and decrease drying times. Higher temperature may have a negative effect. Always test surfaces before utilizing higher temperatures.

Dwell time

Dwell time is the amount of time a cleaning product is allowed to remain in contact with contaminated surfaces. Dwell times vary from one product to another. To maximize cleaning pretreatment performance, always follow manufacturer dwell time specifications.

When engaging in restoration work, keep these six principles in mind and use them to your advantage.

By Bill Weigand, Gary Loiben and Gary Funari. Excerpted from The Complete Guide to Restoration (Burlington, Wa.: Dri-Eaz Products, Inc., 2014).