A dirty chimney with only a quarter inch of soot contains the highly flammable substance called creosote. A hot fire around 1000 degrees F. could easily ignite this substance into a roaring chimney fire. At the height of a chimney fire, the creosote can burn at temperatures exceeding 2000 degrees F. Flames and flying embers can easily land on the roof and ignite the wood framing of your home. The intense heat can cause the flue to crack or collapse thus causing the interior walls of your house to burst into flames.
Creosote in chimneys comes in several stages. In its flaky, soot form, it is easily brushed away leaving safe and clean flue walls. When it appears as hard, brittle deposits, the chimney sweep's extra efforts in brushing will remove most of the build-up. But the nasty glazed variety is truly the most dangerous form, and the most difficult to remove in many instances.
Glazed Creosote in your chimney is recognizable by its dense, shiny tar-like appea rance. This unpleasant substance is basically wood tar which has become baked onto the walls of the chimney or flue lining. Once it gets burning in your chimney, it is extremely difficult to extinguish.

What causes glazed creosote to accumulate?

Unfortunately, there is no such thing as creosote-free wood burning. Creosote accumulation will occur no matter what kind of wood is burned and no matter what kind of wood burning system is used. What determines the type of creosote and its severity is how the fuel is burned. Solid fuel authorities agree that the amount of smoke, the temperature of the fire and the regulation of air (turbulence) are the major variables which determine the amount of build-up. A low burning fire, for example, will result in incomplete combustion, the number one cause of glazed creosote accumulation. An improperly installed fireplace insert, one that allows the smoke to cool too quickly in the firebox, is another situation which causes severe glazing. To combat this problem, flue gases should be kept between

250 degrees and 500 degrees F. if creosote accumulations are to be reduced in amounts of thickness. (Be sure to ask your chimney sweep about proven methods to assure correct burning.)
If your chimney sweep has already diagnosed glazed creosote as a problem in your chimney take his or her advice seriously. DO NOT continue to use your affected fireplace or wood stove. The simple fact is that a hot fire could easily ignite the glazed creosote and result in a dangerous chimney fire. And a low burning fire under such hazardous conditions will only worsen the glazed creosote problem.

Can my chimney be treated?

Yes! There is now a product available to professional sweeps for removing glazed creosote. It's called TSR, or Third Stage Remover. Simply stated, this strong effective formula of fine cleaners dissoves baked-on resins from masonry, metal and stainless steel surfaces by reducing the hard glazed substance to loose, brushable soot.
The TSR application will involve hard work by your chimney sweep, but the results will be worth the extra effort. After the product is applied, a drying time of 24 hours or more is required. As is often the case, several days may be necessary for complete drying to occur before brushing can begin.
Sometimes, the glazed creosote build-up is extremely think and difficult to completely remove in just one application. Therefore, the more severe instances of glazing can require two or three application of TSR for 90% to 100% removal.
It is important to keep in mind that your professional sweep is able to suggest valid and honest correc tive measures in making your home safe from chimney fires. Your family's safety and protection of your personal property are the professional sweep's primary concerns. To effectively remove hazardous glazed creosote from your home, take the time to discuss TSR with your sweep. Should you desire more information on glazed creosote and other possible fire hazards in your home contact your local fire chief or marshal.

If this was the only reason for installing a cap it would be enough. I have seldom seen an uncapped chimney over five years old that was not suffering from some kind of water damage. Go over to your fireplace right now and look at the back fire wall near the base. Take a screwdriver or coin and run it across the mortar between the bricks. Seem a little crumbly? Or maybe it's obvious just looking at it. Rain puddles up on the smoke shelf, mixes with creosote in the chimney and turns into a highly corrosive acid which seeps down and attacks the mortar joints on the back wall of the fireplace. The mortar becomes weak and presto, the bricks on the wall become loose. Besides that:
Rain can set off a bad smell in the chimney. This will happen in warm weather, especially if the chimney is dirty or has animal droppings on the smoke shelf.
Rain speeds the rusting of metal parts of your fireplace. Damper hard to move or frozen?

A cap keeps out birds, squirrels and other varmints

Birds are fun to look at but they do have a few bad qualities when perched on your chimney.
They chirp and flutter constantly, driving sane folks nuts and crazy folks bananas.
Their droppings accumulate in a huge vulgar mass on the smoke shelf causing a bad smell, is a breeding ground for mites and bacteria.
A squirrel can wreck a house faster than a dozen two-year-olds.
Once they get inside the chimney the only way out for them is through the damper. Raccoons love to raise their young in the nice dark and warm smoke shelf, just a couple of feet from your living room.

Backpuffing (fireplace smoke coming back into the house) can result from several factors. One of them is downdrafts.

A cap keeps out leaves

Leaves can choke a flue and set off a chimney fire in a dirty flue. As you can see, there is probably no single investment that you can make for your chimney that will return so much to you. You have invested $5,000.00 - $10,000 in your fireplace, why not protect that investment.
Which of these chimney caps is best for your chimney? Ask the professional who handed you this brochure. They have the experience in your local area to help you make an informed decision.

The two main reasons for the breakdown of fireplaces and chimneys are heat and water.

A chimney cap takes care of the water damage, the "heat reflector/heat shield" takes care of the heat!

In and unprotected fireplace, heat is absorbed into the back wall of the fireplace which causes the bricks to crack and the mortar that holds the chimney together to break down, leading to expensive repairs.

A fireplace with a "HEAT REFLECTOR/SHIELD" protecting it. The back wall of the fireplace is now exposed to 1/3 less heat. The heat is radiated into the room where it should be and damage to the fireplace is significantly reduced or stopped! How much additional heat? 20% to 40% increases are being reported depending on the fireplace. Whatever the increase, it's always noticeable. You'll feel the difference.

• Open the damper
  This is forgotten more often than most people care to admit.
• Ingredients
  You will need three things to start a fire.
  1. Tinder. Crumpled up newspaper makes the best tinder. You can also use small twigs, pine needles, or pine cones.
  2. Kindling. Large twigs, small branches, and small splits of wood anywhere from 1/4" to 1" in thickness will do. This is the most important ingredient for building a good fire and usually the most over looked.
  3. Fuel. Use only well-seasoned hardwood. If you have to burn softwoods, be certain they are well seasoned. Look for split, dry wood that has been stacked for up to a year. Loose bark and cracks in the ends are signs of seasoned wood.
• Starting the fire
  Arrange two small to medium sized pieces of firewood on the grate, and place some crumpled up newspaper for tinder between logs.
  Now cover the tinder with several pieces of kindling. Be generous with the kindling - it's the most important element in starting your fire.
  Now, place two more pieces of firewood on top of the kindling and two more at right angles to these two. Leave some space between the logs for air circulation.
• Warm up the flue
  For fireplaces, warm up the flue by holding a piece of burning rolled-up newspaper in the (opened) damper region for 10-15 seconds. This helps the flue establish a good draft. Then light the tinder. Within a few minutes, you should have a nice, hot roaring fire!
• Important dos and don'ts
  DO check the manufacturer's guidelines for your wood stove or insert.
  DO use seasoned hardwood.
  DO use commercial fire starters if you like. They eliminate the need for tinder and reduce the amount of kindling required.
  DON'T use charcoal lighter fluid or other flammable liquids. These are extremely dangerous. (Gel fire starters are okay.)
  DON'T use coal in a wood stove or fireplace unless there are specific written instructions - it will burn, not safely.
  DON'T burn artificial logs in a wood stove, unless they are specifically designed for wood stove use. Artificial logs can dirty the chimney much faster than regular wood, and can be hazardous in certain situations.
  DON'T burn treated lumber, trash, or anything other than wood in your fireplace or wood stove.
  Valuable troubleshooting hints
• Smoke problems
  Is your damper open? If it is and the smoking continues, open a nearby window a crack for a minute or two until the fire is going well - then you can close it again
  If it just smokes when you light the fire, it may be because the flue is cold. Did you warm the flue with a burning rolled-up newspaper held in the damper region? (If not, that usually works.)
  If the chimney continues to smoke, call a chimney professional. Your chimney may be clogged by animal nests or an accumulation of soot and creosote, or it may have additional problems.
• Chimney odors The sour, sickly odor is the smell of creosote. The solution is to call a chimney professional to clean your chimney and install a chimney cap to prevent water from entering and reacting with the creosote. Your chimney professional can also recommend a good chimney deodorant to handle any remaining odor which has been absorbed into the masonry.
• Creosote buildup Slow smoldering fires and/or the use of unseasoned wood can create "cool" smoke and weak draft. Under these conditions the smoke condenses and sticks to the chimney's interior. Forming highly flammable creosote. Read our section on "Efficient Burning Techniques" for the solution of this problem.

The key is to burn small, hot fires, using hardwood that will minimize creosote accumulation and maximize heat output.

Keep fires burning hot with flames, not smoldering with a lot of smoke.

Be careful not to add too much firewood. In a fireplace, keep the top of the flames visible below the fireplace opening. In a wood stove, keep the flames confined to the wood stove itself.

With glass doors, keep the doors wide open with the screen closed for a good half hour after starting the fire. When you see the fire is burning well, close the doors and set any draft controls.

It's better to add smaller loads more often than to cram in a lot of wood trying to get an all-day burn.

When you're ready to put out a fire, separate the logs by moving them to the side of the fireplace or stand them on end in the back of the fireplace. Close the screen or glass doors tightly, but don't close the damper until you're sure the fire and coals are completely out.

How to avoid chimney fires

• Creosote is the main cause of chimney fires
  A buildup of creosote is highly combustible and can result in a chimney fire. To minimize creosote:
  Burn only seasoned wood
  Do not burn trash in a fireplace or wood stove.
  Don't allow the fire to smolder.
  Contact your chimney professional to clean your chimney regularly.
• What to do if you have a chimney fire
  Get everyone out of the house.
  Call the fire department.
  Don't close the damper. If you have a fireplace with glass doors, close the doors and the vents. If you have a wood stove, close the doors and the air inlets.
  If flames are visible at the chimney top hose down the roof but not the chimney. Spraying water on a hot chimney will very likely damage it.
  Call a chimney professional before using it again. Even a small chimney fire can damage the chimney, making it unsafe to use.