Electric sparks?

[yuryk]

Dear Community!

I'm enjoying my new wood stove for the second winter, mostly because of this forum

I've noticed an interesting phenomenon. Sometimes, not always, when I am levelling glowing/burning coals for the next load, there is something I do, that causes sparks to appear to be travelling like electricity, like a lightning. It feels like static electricity for some reason... it also feels like it travels through the air and the directions change very quickly, resembling a lightning. I tried to catch it on video for multiple unsuccessful times, but finally did it:

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"Normal" sparks just travel up and to the sides. But these travel predominantly horizontally and most of the time from the stove into the room.

Do you guys know what is it and what causes it to appear?

 

[Dieselhead]

That’s common with 2 species of wood that I’ve burned. Black Locust and shagbark hickory are the worst with it. You pretty much need eye protection in the form of a face shield when reloading with either of those.

Free fireworks show….

 

[bigealta]

Yup Locust does that easily.

 

[yuryk]

Interesting, thanks! So, what is that? It doesn't look like spark is flying out of the box... but rather looks like something ignites in the air...

 

[yuryk]

Forgot about AI, should have asked it initially... But since I posted already, here is what it says for anyone else curious:

What you’re seeing is real, and it has a name — but it’s not static electricity and not true lightning.

It’s most likely a combination of:

✅ 1. Magnesium / mineral “hot jet” sparks jumping from disturbed coals​

Firewood contains small amounts of minerals — magnesium, potassium, and sodium, especially if the wood has bark, knots, or dirt contamination.

When you level or rake the coals, you can momentarily create:

• Tiny particles of burning magnesium/potassium
• That burn extremely bright
• And move unpredictably
• And can seem to “ignite the air” as they fly

These don’t travel in simple ballistic arcs like normal sparks — because they react with oxygen as they fly, so they appear to “draw” bright zig-zag paths.

Why they look like lightning​

Magnesium/potassium sparks burn so fast that:

• The light is white or electric-yellow
• The motion looks jittery or zig-zag
• The spark path looks like it is appearing in mid-air, not coming from a coal

This makes your brain interpret it as “electric.”

This exact effect is used intentionally in fireworks (“titanium/magnesium fountains”) that create lightning-like sparks.

✅ 2. “Flashover” of airborne wood gases when hot coals are disturbed​

When you rake coals, you suddenly release:

• Unburned pyrolysis gases (CO, hydrocarbons)
• Superheated air pockets
• Fine carbon dust

If there is a brief mixture of oxygen + hot volatile gases, it can ignite instantly in little flashes away from the coal bed— which looks like spark paths forming in the air. This looks like:

• Thin, branching streaks
• Appearing a few inches above or outside the stove
• Not clearly linked to a single coal

This can look exactly like small lightning.

✅ 3. Turbulence + hot carbon particles suspended in air​

When you rake coals horizontally, the draft changes for a moment:

• Air flows outward instead of upward
• Fine incandescent carbon dust blows into the room
• The turbulence makes the particles flicker and zig-zag

Those carbon micro-particles are so small they don’t fall like sparks — they float and burn in the air.

🔥 Why you sometimes see it only when leveling coals​

When leveling, you produce the perfect conditions:

1. Crush a hot ember → release fine reactive particles
2. Expose fresh charcoal → instant gas release
3. Disturb the airflow → outward bursts instead of upward draft
4. Bright magnesium/potassium flashes → look like lightning
   

That combination doesn’t always happen — so the “lightning” appears only occasionally.

🛑 Safety note​

Since the flashes move horizontally into the room, that means at least some micro-embers are escaping.

If your stove has no spark screen and the door is open:

• Put a fire-screen in front
• Avoid leveling coals with the door wide open
• Make small, gentle motions
• Keep combustibles > 3 ft away

These flashes are usually harmless but can ignite dust, carpet fibers, or newspaper if a hot micro-particle lands on them.