The Three Types Of Creosote

Did you know that whenever you burn wood in your
fireplace, creosote is deposited in the chimney lining?
“Creosote” is the name used for wood-burning byproducts,
and it consists of a mix of creosote, tar, and soot. Creosote
buildup in your chimney has three degrees, each different
from the other and each more difficult to clean and
potentially more hazardous than the previous degree.
Possibly the most important reason to get an annual
chimney cleaning and inspection is to prevent chimney fires
caused by creosote.

1st  Degree Creosote

The type of buildup you want in your chimney liner is first
degree creosote. This type has high soot content and can be
easily removed with a basic chimney brush.

First degree creosote is produced when the flue is warmed
by the fire’s heat, there is good wood combustion, and the
fire gets plenty of air. The best way to achieve good wood
combustion is to burn only seasoned firewood; when
firewood is seasoned, it has low moisture content. Houses
today are often sealed too tightly, which can cause the air
supply in the fireplace to be restricted, which in turn causes
smoke to enter the home and prevents the flue from
warming properly. 

2nd  Degree Creosote

A chimney which has a restricted amount of incoming air
sets up the right conditions to produce the second degree of
creosote. Restricted air is commonly caused by fireplaces
and wood stoves that have glass doors. This degree of
creosote looks like glistening black flakes. The flakes contain
hardened tar, and they are not easily brushed away.
Removing creosote is essential for safety reasons, but
achieving it is only easy with first degree creosote. A rotary
loop is most often used to remove second degree creosote.
This equipment consists of a stainless steel cable attached to
a hub which has metal rods that are turned by a special type
of powerful drill. Some people mistakenly believe that a
rotary loop damages their chimney liner, but what really
happens is that the liner is already damaged and the cable
knocks it loose. 

3rd  Degree Creosote 

Third degree creosote is extremely concentrated fuel that
looks like tar running down or coating the inside of the chimney.

The creosote hardens and is repeatedly recoated. If the creosote in the liner
catches fire, third degree creosote may burn up, but it
usually does not. Instead, the creosote partly boils and partly
burns, leaving a light-weight “sponge” that is simple to
remove. However, if it is not cleaned and creosote fills the
spongy substance, your chimney can end up with more than
100 pounds of creosote and a highly combustible chimney.
Some of the conditions which cause third degree creosote
are:

• When combustion is incomplete and/or the flue isn’t
  sufficiently warmed
• The chimney is not insulated or is cold for some
  other reason
• Unseasoned wood is being burned
• The house is sealed tightly enough that there is an
  insufficient amount of combustion air
•  The flue is oversized

Cleaning third degree creosote is very difficult, and the best
course of action is often to simply replace the chimney liner.
Options for removing the most difficult degree of creosote
include using a rotary head with chains and using chemical
creosote removers.

Not sure what kind of creosote you have? Book an appointment and let us take care of it.