The facts about creosote and tar

What is Creosote?

When you burn wood, it produces a number of components in addition to ash, including creosote. Generally, the mix of tar and creosote is just referred to as creosote.

Soot is just that, and is removed by sweeping a chimney.However, creosote and tar removal is more difficult.

Typically there are three types of creosote found in chimneys, and in the trade, they are usually called stages or degrees. Whatever stage the creosote is at, it is combustible, that is it ignites, so it should be removed.

Stage one (or first degree)

This is a normal level. At this stage, the creosote has a high percentage of soot and can be removed from a chimney easily and effectively by a chimney sweep. Stage one creosote develops when the wood burns well and at a high temperature and is standard when there is plenty of air and heat can easily disperse up the flue.

Stage two (or second degree)

This stage occurs when incoming air is restricted, and you’ll often find it in flues with an open fire or woodburner. When it gets to this stage, things become a little more challenging. You’ll see black flakes and lots of them. However, it can still be removed by a chimney sweep, but may take a couple of visits as it can be stubborn.

Stage three (or third degree)

You don’t want this.

Stage three creosote build-up occurs when the chimney (flue) temperatures are low. This can happen through slumbering a wood stove (shutting down the controls to minimal) or using wet or unseasoned wood.

An inspection of your chimney will quickly identify if you have stage three creosote. Firstly, you’ll be able to smell it (think of road tarmac being put down and you are stuck in traffic). Also, if it’s particularly bad and you have an open fire, you’ll see black liquid running down the chimney.

Chimney sweeping by a reputable, professional sweep will remove stage one and stage two, but stage three requires a more intensive treatment.

Chimney brushes are the standard method for removing first and second degree creosote. At stage three, chemicals can break down the creosote and leave you with a clean, efficient flue.