Sometimes sitting around a fireplace with friends and family can feel like the most comfortable place in the world. Other times, the firewood can start popping and crackling, and someone can end up with a burned arm or a blanket briefly lit on fire. The difference between those two experiences has everything to do with your firewood.
Fires pop and crackle because the moisture that is stored within small pockets of the wood fibers turns to steam in the lit wood. The trapped gasses eventually build up enough pressure to find a way to burst out of the wood. Firewood with a lower moisture content will pop and crackle much less than wood with a higher one.
To learn more about why firewood pops and which kinds of wood pop and crackle more than others, read on.
Why Do Fireplaces Pop?
The popping and crackling of an indoor fire, sizzling away in the fireplace on a cold winter evening, is a classic scene that many people think of with fondness and longing. It brings with it an aura of coziness, safety, warmth, and kinship. For many people, it might also come with the question in their mind of why that popping is happening or, if it isn’t happening, they may wonder what changed to keep the firewood quietly burning without as many sounds or disturbances.
Why Firewood Pops When It’s Burning
Perhaps you have had to cover your eyes as a small piece of wood came flying out at you after a particularly aggressive “pop” from the fire.
Did it make you wonder what was causing that popping and crackling that almost lit your sweater on fire? After all, the sounds are not just sounds; they’re a product of a chemical and physical reaction.
Wood has a reputation for containing some amount of water within the porous grains of the wood fibers. When those water particles begin to heat up, they undergo a chemical process that turns them into gaseous steam.
That steam can get trapped within the wood, building and intensifying in pressure until it eventually finds an escape and bursts out into the open air with a sharp sound and sometimes particles of wood or lit embers flying with it.
Always follow safety protocols when lighting a fire in a fireplace to avoid any disasters, and you can sit back and enjoy the sounds and sights of a live burning fire warming you up from the outside in.
The next time you are watching a burning fireplace, and you hear those popping and crackling noises, relax, knowing that it’s just the moisture inside the wood that is heating up, boiling, evaporating, and then bursting out with any other trapped gasses within the fibers of the wood.
Why Some Wood Pops More Than Others
It’s no secret that there is a multitude of kinds of wood in the world. Every plant and tree has its own wood type, which probably leaves that list reaching into the millions. Although any wood will burn when dry enough and exposed to a flame, there are just a few kinds of wood that are more commonly used for firewood.
Firewood has been around for centuries, and the art of burning a fire inside a fireplace is nothing new to mankind. Like everything, though, it’s become more of a science now, and people are discovering which woods burn hotter, longer, and with less smoke. Efficiency has become a priority for many regular firewood users.
Some of the best woods to use for firewood include but are not limited to:
These can often be found as firewood for a fireplace, and there are many reasons for that. Most people prefer to find a wood that will not pop and crackle too much, simply for safety and convenience.
The woods that don’t pop and crackle as much are dryer than the ones that do. Most often, the water content will be at or below 20%, possibly closer to 15% in some instances.
The higher the water content, the more the snap, crackle, pop, so to speak.
Different Wood for Different Environments
When choosing firewood, it is essential to consider the water content and how that will affect your fire burning experience. If you’re in a situation where the crackling and popping are undesirable and looking for more quiet and efficient firewood, choose wood with low water content.
On the other hand, if you’re hoping for that classic experience of sitting around a fire and hearing the crackling noises as you sip a mug of cocoa and warm your slippered feet, then choosing a wood with a slightly higher water content would likely suit your needs.
Which Firewoods Pop the Most?
If you are choosing your firewood and want (or don’t want) a crackling fire, knowing which ones produce the most pops and spits can be helpful.
According to Mychimney.com, Pine and Fir are considered one of the cracklier woods to burn. Not only this, but they also have a great aroma that many enjoy during the winter and holiday months.
These are both in the category of wood called softwoods. Softwoods, as opposed to hardwoods, tend to pop and crackle much more than their counterparts. This has to do with the higher sap and water content.
Sap is a sticky, syrupy substance that is produced and contained within many softwood trees. You can often see it dripping off of their trunk or branches when walking by them. The sap is harmless and often easily ignored.
It can be found more within the pores and fibers of wood along with the typical water content that keeps all trees alive and thriving before they are cut down or dry out and die on their own. This sap content within the pores reacts similarly to water when heated.
The sap will burn and produce a gaseous substance. As it continues to burn, the pressure within the pores and gaps of the wood will rise until it cannot be held in any longer, and it will burst through the wood and into the open flames.
Saps often bring smoke with them as well when they finally crackle and burst out, and that can be an annoyance for those sitting around the fire who then have to close their eyes and hold their breath to avoid inhaling the unhealthy fumes.
Softwoods that can be used as firewood include but are not limited to:
There are much fewer of them, and they’re not used as often as hardwoods for firewood. This is partially due to their tendency to retain that sap and have increased incidences of popping and crackling.
Most firewood is taken from hardwood sources because those types of wood will burn longer and more efficiently. If the popping and crackling are what you’re after, though, softwood may be the way to go.
Does Seasoned Firewood Pop Less?
Not only are there many types of wood that are used for firewood among the softwoods and hardwoods, but there are also different processes that the wood can undergo to dry it out properly before use. The two most commonly used processes are kiln-drying and Seasoning.
Kiln-dried wood is wood that has been cut down and then brought to a kiln-drying facility. After the wood is chopped and sorted, it is then placed in a kiln. These can be powered by solar energy, electricity, or steam.
A kiln is essentially a large area, or oven, that can be heated up. Kilns heat up firewood to temperatures that effectively dry out most of its moisture. Kiln-dried wood can reach water content levels as low as 10% in some instances and almost always keep its wood water content levels below 20% (which is the standard for seasoned firewood).
The kiln-dried wood, because it’s typically drier than the seasoned wood, will produce much less crackling and popping than its counterpart. It burns quickly and a little bit hotter as well. Additionally, kiln-dried wood is slightly less efficient in its energy usage and heat output for the expanse of time it is burned.
Although this process is much quicker and produces drier wood, many people still prefer to buy and burn seasoned firewood instead.
When a piece of firewood is referred to as “seasoned,” it means that it has undergone a process of drying and aging. This typically requires the wood to be exposed to the following conditions:
- All wood pieces laid out in a single row
- Wood exposed to direct sunlight
- Wood exposed to a large quantity of wind
- They were left out in these conditions for one “season”, or year
Many still prefer the seasoned wood over the kiln-dried wood because it retains slightly more moisture and, therefore, will create more pops and crackles during the burning process.
The higher water content also allows the wood to burn more efficiently. The water will keep it just cool enough to not burn off too quickly, but not too much that it limits the heat coming off of the fire. For some people, seasoned firewood is the ideal type of firewood.
So, whether you love the pop and crackle, or you prefer quieter and more predictable firewood to burn in your fireplace, you can find the wood that suits your preferences and needs.
Pellets Don’t Pop
Firewood can be found in a few different forms, as we’ve discussed. One of those forms is pellets. These are less common and less traditional, but they’re quickly becoming a favorite for many who use wood-burning stoves, ovens, or fireplaces.
This is because they are very efficient and convenient. A few of the pros to using pellets are:
- They take up less space than traditional firewood, coming in bags ranging from 5-50 lbs.
- They burn hot and for a longer time than some other firewood.
- You can find softwood and hardwood pellets, as well as some that have a combination of the two.
- They are drier than other forms of firewood and, as such, pop and crackle a lot less.
So, if you haven’t tried them already, or if you have been struggling to find firewood that you really like, consider buying a bag of wood pellets and testing them out. You might find yourself joining the party of pellet burners.
What Not To Burn: Treated Wood
There are often instances when you finish a project involving woodworking, such as building furniture or other things, and you have treated wood scraps left over. They look like the perfect size and shape for burning, and it seems like a shame to let them go to waste.
It may be tempting to add those into the mix with your firewood, but treated wood should never be burned.
These kinds of woods have been treated with harsh and dangerous chemicals that should never be burned. The smoke is dangerous when inhaled, and is a hazard to the environment as well.
Instead, consider saving them for a different project, giving them to a friend for their project use, or safely disposing of them. They should never be used as firewood.
Is Popping Firewood Dangerous?
A popping fire can be dangerous: anytime a fire pops or crackles, it is a product of a burst of hot gas escaping from within the wood. With that burst often comes a lot of flaming embers, small pieces of wood that are hot or on fire, or other hot particles that could land on someone or something.
Popping firewood may be a controversial topic. As with most things, it all comes down to situation and preference. It is best to get as much information as you can about the possible dangers of a popping fire so that you can make an educated decision about your situation.
Since these particles, embers, or chunks of wood are likely burning hot, if not still flaming, whatever (or whoever) they land on could potentially catch on fire or suffer burns and damage.
Popping Firewood Can Catch Objects on Fire
If it is not a person that is in the line of fire, but instead a flammable object, such as blankets, clothing, furniture, or papers and books, then there is a risk for a greater uncontrolled fire starting outside of the fireplace.
Luckily, there are some steps you can take to ensure that these dangers are minimized or negated completely, even should you choose to use firewood with higher water content:
- Clear any flammable material away from the fireplace area before starting it.
- Move any furniture, pillows, blankets, or books back further away from the fireplace.
- Keep all children and pets away from the fireplace at all times during the fire burning process.
- Use a glass or metal cover over the fireplace opening to block any embers or particles flying out with the bursts.
- Keep a small amount of wood burning at a time, never loading too much into the fireplace.
- Have a fire extinguisher nearby and easily accessible during the burning process.
These can help you to still enjoy those classic and mesmerizing crackling and popping noises while keeping your friends, family members, pets, and belongings safe from the potential dangers of the popping, burning wood.
Consider using much dryer firewood with significantly lower water content. This will ensure that there will be much less crackling and popping in the fireplace as the wood burns.
How to Prevent Wood from Popping
If you have read through this and found that you feel nervous about the risks associated with the random and unpredictable popping and crackling of a lit fire, then you can follow this step-by-step list to ensure that you end up with minimal popping and crackling.
You can prevent your wood from popping by:
- Properly clean in and around your fireplace before use, ensuring that no dust or leftover debris remains.
- Purchase a hardwood that has been kiln-dried, rather than seasoned, with the minimum water content offered.
- Start slow with your fire burning and keep it organized.
- Don’t add too much wood to the fireplace at once; use one block at a time if possible.
Once those steps are followed, you can be sure that your firewood will not be popping and crackling nearly as much as if you had not taken them. You can enjoy your quiet, peaceful fire without the worry of embers flying or wood particles catching your slippers on fire.