How to Get Hot Spots Out of Coils
A fresh build should heat evenly from end to end. When one part of the coil glows before the rest, you’ve got a hot spot, and it’s worth fixing before you add cotton.
This easy tutorial explains what hot spots are, what causes them and how to get rid of them on both contact and spaced coils, step by step. Where the hot spot is will affect what you do about it, so we’ll cover that too.
Prefer to watch? Watch ZampleBox Vape School videos on YouTube.
Short version: Check the resistance first, then pulse the bare coil at low power and watch the glow. Pinch or strum the wraps with ceramic tweezers until the coil heats evenly, let it cool, recheck the resistance and only then wick it. Never use metal tools on a firing coil, and never dry-fire a coil that already has cotton in it.
What is a hot spot?
A hot spot is an area of the coil that heats up faster than the rest. You’ll see it as a spot that glows first, or glows brighter, when you fire the coil without a wick.
Hot spots cause trouble once the coil is wicked:
- A burnt or harsh taste, because the cotton scorches at that spot
- Uneven vapor and muted flavor
- A shorter life for your build, since the cotton and wire wear faster where it’s hottest
If your vape already tastes burnt, our guide on why your vape tastes burnt covers the other usual causes.
What causes hot spots?
- Uneven wraps. Small gaps between the wraps of a contact coil, or uneven spacing on a spaced coil.
- Kinks and nicks. A bent or damaged section of wire can heat faster than the rest.
- Uneven tension. Wraps pulled tighter in some places than in others.
- Residue. Old gunk left on a coil you’re cleaning and reusing.
Read the glow
On a contact coil, the center lighting up first is normal. What you’re looking for is a single wrap, or a spot off to one side, that glows ahead of its neighbors. That usually means a gap or a kink right there.
If a coil leg glows, it may be longer than it needs to be, so trim it closer to the post. And if the resistance reading keeps jumping, a post screw is probably loose.
What you’ll need
- Ceramic-tipped tweezers. They don’t conduct electricity and they handle heat, so they’re the only tweezers to use on a coil that’s firing.
- An ohm reader, or a regulated mod that shows resistance.
- A regulated mod for pulsing, if you have one. It lets you fire at a low, steady power.
- A small flat screwdriver or a coil rod for adjusting spaced coils.
Missing something? Our DIY coil building kit guide covers the tools.
How to remove hot spots, step by step
1. Check the build first
Before you fire anything, check the resistance. It should be steady and close to what you expected. A reading that jumps means a loose leg; a reading far lower than expected can mean a short, such as a coil touching the deck or the top cap. Fix that before you go on.
2. Pulse at low power
With no cotton in the coil, fire it in short pulses of a second or two at a low setting. Watch how the glow spreads. A contact coil should light up from the center outward, evenly on both sides.
3. Pinch contact coils
If one wrap glows ahead of the others, gently squeeze the wraps together with your ceramic tweezers, working along the coil. You can do this while pulsing or between pulses. It closes the small gaps so every wrap touches its neighbor evenly.
4. Strum the coil
Run the tweezer tips lightly across the wraps, a bit like strumming a guitar, while you pulse. This helps the wraps settle into an even shape.
5. Adjust spaced coils
Spaced coils have a small gap between every wrap, and those gaps need to be even. Let the coil cool, then nudge wraps with the tip of a small screwdriver or your tweezers until the spacing looks uniform. Pulse again to check.
6. Repeat, then let it cool
Keep pulsing and adjusting until the whole coil glows evenly. Let it cool completely, recheck the resistance and check that the post screws are still tight. Then it’s ready for cotton.
Dual-coil builds
With two coils, both should start glowing at the same moment and at the same rate. If one lags, check that both have the same number of wraps, sit at the same height and have legs of similar length, and that every post screw is tight. Our guide to building a parallel coil covers matched builds in more detail.
Safety tips
- Never dry-fire a coil that already has cotton in it.
- Never touch a firing coil with metal tools or your fingers, and let the coil cool before you handle it.
- Keep pulses short and the power low. You only need enough heat to see an even glow.
- Not every wire should be glowed. Wires used for temperature control, such as nickel and titanium, generally shouldn’t be dry-fired red hot, so follow the wire maker’s guidance.
- If you use a mechanical mod, confirm the resistance on an ohm reader and read mechanical mod battery safety before you fire.
After the fix: wick and vape
Once the coil glows evenly, thread in fresh cotton, trim and tuck the tails, and saturate it with vape juice. Start at a low wattage and work up. If you get a sudden harsh, burnt puff, stop and re-drip; our guide to dry hits explains how to avoid them.
A clean, even build is the best way to taste a new bottle properly. Browse our vape juice, or let the Zamplebox Club send bottles picked for your taste every month.
Common questions
Can pre-made coils have hot spots?
Pre-made coil heads are sealed, so you can’t adjust them. If a new coil tastes burnt, make sure it was primed properly; if it still tastes off, replace it. See when to change your vape coils.
Why use ceramic tweezers?
Ceramic tips don’t conduct electricity and they handle heat, so you can pinch and strum a coil while pulsing it without shorting the build.
Should a contact coil glow from the center or the ends?
From the center outward. The legs draw some heat away at the ends, so a well-built contact coil lights up in the middle first and the glow spreads evenly toward both sides.
How often should I check for hot spots?
Every time you build a new coil, and whenever you clean and re-wick an existing one, since cleaning can shift the wraps.
WARNING: This product contains nicotine. Nicotine is an addictive chemical. For adults 21+ only.