Black spot stains on ceilings and walls, furniture, HVAC filters, and content have been a major cause of increased claims by insurance companies and commercial property managers. This problem is known as “black soap deposition” (BSD), and it is often caused by common household ornaments.
There is no evidence that BSD was caused by a sudden or unintentional source, such as gas water heaters or malfunctioning furnaces. There was not much evidence until recently to support the claim that BSD originated from somewhere else. However, tests have shown that decorative scented candles could be the primary cause.
Low quality candles are often to blame
Research shows that increased BSD can be caused by candle manufacturers adding fragrance oils to their products and customers trimming the wick incorrectly. Many fragrance oils aren’t suitable for combustion and don’t burn cleanly. Many amateur candle-makers are trying to profit from the growing popularity of candles. This has led to a proliferation of low-quality candles in many homes, and an increase in indoor soot deposits.
Possible dangers to health and structure
Each year, the number of aroma candle makers, both professional and amateur, increases. Many of these candle manufacturers add candles to their product lines without having the necessary knowledge to make safe, clean-burning products. Chemical testing has shown that some candles emit more than 20 volatile organic compounds, lead, and significant amounts of carbon.
People living in or working in commercial buildings, homes, and apartments can be exposed to serious health risks by lighting scented candles. It can also cause damage to the ventilation system, furniture and contents. Evidence shows that even a micron of particulate matter can cause respiratory problems. According to the American Lung Association and Environmental Protection Agency (EPA), particulate matter 2.5-microns in size is harmful to human health. These particles can be inhaled into the lungs and cause irritation. People with heart disease or lung disease, children, and the elderly are at greater risk.
First Signs of BSD
A dingy gray appearance on fabrics or upholstery with light colors is the first sign of candle soot deposits. Plastic items can accumulate a black film and electronic equipment may show discoloration near the vents. A thin black residue also develops on TVs and computers screens.
Wall-to-wall carpet can cause discoloration and darkening in homes, apartments, and commercial buildings. Bed ruffles, vertical blinds, and draperies can also attract deposits.
Testing is key to identifying the primary source of BSD
Testing was done in a Florida model home to prove that such candles can cause damage. It measured 2,800 square feet and had a central air conditioning unit. After three days, the soot deposits from four candles had become so obvious that testing was stopped. The total time spent on the candle-burning process was less than sixty hours.
Another test was performed in a 144-square foot room with candles taken from the same model house. The test revealed that particulate levels reached over 11 million particles per square foot in thirty minutes.
The science behind BSD
Inefficient combustion can cause candle materials to burn poorly. Hydrocarbons are the main ingredient in black soot. The production of candle soot begins when the amount of particulate matter is between.06 and 0.1 microns. Because they are statically charged, soot sticks to plastics and optical devices.
To prevent soot deposits from building up, there must be a driving force, such as gravity, electrostatic attraction, or a forced air unit, to push the particulate matter towards a surface.
These soot particles will eventually combine with the dust particles in the atmosphere and become one over time. This soot eventually settles on surfaces due to random collisions between the particles. Brownian Motion is an assumed random movement of suspended particles. These particles can grow in size and mass when they unite to form gravity.
You can check the interior of your home for any scented candles if a resident, homeowner or business manager calls you regarding these mysterious black spots. These candles can temporarily improve the air quality, but they can also be harmful to the building’s inhabitants.