Wick Testing The New Iridescent Vessels!

Unfortunately, I was running into a sort of Goldilocks problem where one wick would create a full melt pool in about 2 hours, but needed constant trimming to prevent carbon buildup and the black soot that can create. That suggested that that particular wick was too large for the vessel. However, one size down produced tunneling. Too small.

Hearing my fellow candle makers rave about the CD series of wicks, I procured a testing kit from the brand, which was a minor miracle considering most candle suppliers are out of stock at the moment on lots of different waxes and wicks.

I poured three nearly-identical candles using Full Moon as my control scent, partially because its high vanillin content can often slow the melting of wax and I wanted to see what that looked like here. The only difference between these candles is that I used three distinct sizes of the new CD wick.

My plan: to check the candles every hour on the hour to see how the burn is going, then extinguish the wick after 4 hours to trim and refirm before I relight them.

Pro tip! If you're not in the habit of trimming your wicks every four hours, you should be! It's the best way to reduce carbon buildup and ensure an even, safe burn for your candle.

Here are the candles lined up. Left to right: The smallest wick, the medium wick, the larger wick. At the one hour mark, they were basically neck and neck, with a slightly smaller melt pool on the smallest-wicked candle. 


Four hours in, I trimmed the wicks to 1/4" and let the candle re-firm so I could see the melt pool. Both the mediums and the large had gotten to a full melt pool at about 2 1/2 hours. The small wick never quite got there, but got close.

Here is something I learned recently: the difference between "hangup" and "tunnelling." I had been under the impression that if a candle does not reach its full melt pool of the first try, it is doomed to tunnel (ie, to leave wax on the sides that will never burn down, overall shortening the life of your candle). Turns out, that's not true. If you burn your candles consistently 3 - 4 hours, in a properly wicked candle, that clinging wax should all melt on the second or third burn, even if there's some still sticking to the glass the first time around. This is called "hangup."  If it doesn't melt, then that's actual tunnelling. So I persevered with testing the smallest wick to see what would happen.


This is basically what the candles looked like for the entirety of their second 4 hour burn. Even flames, no smoke or soot, but that first candle still not QUITE achieving a full melt pool.


On Day 2, I did a power burn. I basically lit the candle at 10am and let it go until a little after 10pm, stopping every 4 hours to trim the wick but otherwise leaving it alone. I want to stress that this is NOT a good way to burn YOUR candle. This is something that candle makers do to test how hot the glass gets and how deep the melt pool gets under sub-optimal conditions. All three glasses were safe temperatures throughout this process. And as you can see, on this third burn, the wax on the smallest jar had caught up. It started out slow, but now was pretty steady. All three wicks were doing pretty good with regards to carbon buildup-- very minor wick "mushrooming" on all three.


On day three, I returned to my usual 4 hours on, then trim and re-firm testing schedule. I started to see some sooting. This pic was taken 4 hours after the last wick trimming, and the soot started to appear right around the 3 1/2 hr mark. Now, all paraffin wax (and truth be told, most waxes in general) will soot to some degree-- and unless a candle is truly poorly or unsafely made, it will be within fully safe parameters. That said, it's unsightly and I try to minimize it.

Why do candles soot more at the halfway point or lower? Because when the flame burns lower in the jar, it more easily heats the glass. With hotter air inside the glass interacting with cooler air outside, the flame flickers more. The extra heat inside also produces deeper melt pools than earlier burns, and the deeper the wax pool is, the harder it is for the wick to completely combust all of the energy it provides, so it speeds up carbon buildup / mushrooming, which leads to soot.

So, basically, the goal is to get a safe, full melt pool at this point with as little sooting as possible. As you can see they all have a little bit of soot at the end of a long burn, but nothing really excessive. What's funny to me is that the smallest wick sooted a little bit this time, but produced almost no soot whatsoever for the rest of the test burn! Maybe I didn't trim it enough before this round?



Here's when I really started seeing the difference in the wicks. The smallest wick was consistently performing the best with the four hour burn intervals. It had the thinnest melting pool (around 1/4"), but it was complete edge-to-edge with no additional wax hangup. The middle wax was doing ok, but with more sooting and mushrooming. The largest wick was practically ruled out at this point. It was sooting and mushrooming quite badly.


At 33 hrs in, I started trimming the largest wick every 2 hours because the glass was getting too hot and the melt pool too deep to safely burn it without trimming for 4 hours. (If a wax pool gets deeper then a half an inch, you risk your wick "wandering" too close to the glass, which could cause it to shatter.)

The largest-wicked candle is officially considered a failed candle. Also the medium wick continued to soot much more than the small.


The last full four hour burn. The winner is very clearly the smallest wick! Even though it started out slow and didn't get a full melt pool until its third burning, it caught up and produced, by far, the most clean burn in the second half of its life. 


All three candles self-extinguished shortly before the 41 hour mark. 

As a candle maker, I need to stress that the safest thing to do is to extinguish your candle when 1/2" of wax remains at the bottom of a glass vessel.  

However, I am stress testing these vessels for all sorts of conditions, and we have all let a candle go out on its own at some point, I'm sure. I need to know that this glass and wick combo is safe enough and will not shatter or explode if it is not extinguished manually. If a candle is improperly wicked, this is a possibility, so it is crucial for candle makers to test, test, test. (Also: I see lots of beginner candle makers that procure their vessels from Dollar Tree, etc. Please, please do not do this. Please only purchase vessels that have been thermally tested and are sold by reputable candle supply companies if you intend to use them for container candles!)

Anyway, the winner was clear: the smallest wick will be going into the finished product! It safely self-extinguished, and the vessel was not too hot to be handled when it did. Winner winner chicken dinner!

Thank you so much for reading if you got this far! I'd love to hear more from you about what other aspects of candle-making your are interested in seeing. I also post a lot of my behind the scenes stuff casually at our Facebook Fans group, so join up there if you want to chat candles with a pretty chill group!