Ever had perfectly good and tested candles start tunneling suddenly?

[AudraT]

Hello all. I'm a new candle maker and I've been making and selling candles for about 3 months. I was able to find the perfect wick for my candles and I've done a lot of test burns, sold some candles, and given away some candles all to people close to me. So I've been able to ask people how well their candles are burning and even observe the candles myself. My candles have always burned wonderfully with no tunneling but now I'm noticing some of my candles are tunneling. The only way to fix is to trim the wick longer.
I can't seem to find an obvious correlation between these couple of troublesome candles other than it's possible one of the 5 pound bags of candle wax I was using was bad or it's the sudden cold weather. Since I wasn't keeping lot numbers (which I am going to start doing today!) I can't say for sure what the source of the problem is. I don't really see any strong correlation between wicks, fragrance bottles, fragrance types, a specific batch, cure times (14 days - 6 weeks) and I'm not even 100% certain that it was a bad bag of wax that was the source of the problem.

Whatever the issue is, I think I might try using a slightly hotter wick from now on (CD-24) to make up for any random variables.

Anyone else ever experience a case like this where seemingly random candles suddenly go rouge?

My candles: Freedom Soy Wax / 8 oz candle w/3 inch diameter glass jar / ECO-16 wick / 14 days or longer cure time / 10% fragrance load

[NightLight]

Possible cause for tunneling is hidden sinkholes in wax. I had a wax blend that was hunky dory, then I got a bad batch of wax and crater galore. So when candle was lit there was tunneling.

3 months is not long to test.

Been testing for years

 

Other people will chime in. It takes a long time to know waxes, wick and fragrances, additives. 

Technique going from a couple candles to more.

[birdcharm]

On 1/10/2023 at 4:21 PM, NightLight said:

Possible cause for tunneling is hidden sinkholes in wax ...

 

 

That makes a lot of sense. 

 

I'm not familiar with Eco16s or the wax, but hidden air pocket sounds like a good place to look.

[kandlekrazy]

Did you check the lot#'s on those bags? one may have been a different lot and wax is varying so much these days.  It does sound like sink holes in the wax.  You can poke around the wick and repour or heat gun to help with sink holes.  Cold weather can also factor if the candle cools unevenly sink holes are likely to develop.  A box over the candles while cooling may help.

[TallTayl]

Room temp can change a burn by a wick size or more. My house is kept about 66-68 in winter. Others 72-78. That 10 degrees can throw things way off. Wicking a candle hotter can get you into hot water without thorough testing over several seasons. 
 

If a soy wax, it could be as simple as normal curing of your wax. Or something altogether different. 
 

make sure your normal testing includes a candle burned imperfectly. Don’t trim. Burn longer. Power burn. All will tell you where your limits are. 
 

what exactly do you mean by tunneling? A little extra hang up? 

[AudraT]

Thanks all for the really good info. I did some more test burning and I think what is going on is the ECO-16 wick for the 100% soy candles burn well when they are trimmed 1/2 inch but when you "properly" trim them to 1/4 inch then it isn't quite hot enough. The melt pool reaches maybe 2 1/2 inches within the 3 inch diameter jar and you get tunneling. When I was trimming the wicks before I was just eyeballing it and what I thought was 1/4 inch was actually 1/2 inch.
The solution to this issue is simple: use CD-24 wicks on the 100% soy wax. I had already been using these wicks on some of my other soy candles fragrances and they burn beautifully at 1/4 inch. Originally I thought the fragrances were what was demanding I needed the slightly hotter CD-24 wicks but what was actually going on was I was trimming the wicks to a more accurate 1/4 inch.
Thankfully it is only two candle fragrances that I need to change the wicks on and one of them is a seasonal fall candle that I'm not selling right now anyways. I only have 10 candles in stock of the second fragrance that has the undersized wick. So, turns out this issue is no big deal.

Edited January 16, 2023 by AudraT

[TallTayl]

Do Be aware, most people don’t perfectly trim wicks before lighting.  The average person doesn’t trim at all, and expects the candle to just ”work”. Nobody in my own family trims a wick before lighting despite instructing thousands of people to do so over the past decade and a half of selling candles.
 

  If you wick for a burn based on a  perfect trim you may be getting yourself into a pickle.  Cd24 is a pretty big wick.  Make sure to powerburn and take temps as you burn the candles.  The container temps will often rise sharply during the last half.  Tunneling will be the least of your problems on that case. Each fragrance may need a different sized wick also, depending on the aromachemicals and diluents in the fragrance.  It’s rarely a one size fits all with soy.  

[AudraT]

I leave a wick burning guide with every purchase that says to trim to 1/4 inch plus all the warning labels say 1/4 wick. I also pre-trimmed the wicks too so the first time they burn the candle the wick will at least be accurate. So, do we wick according to the instructions and warning labels or do we wick according to what we think the average person will do?

This is one of the reasons why I always just eyeballed it when I wick trimmed as I figured that's what most people would do, and why the wicks were actually at 1/2 inch when I pulled out a ruler and measured it.

A friend of mine said she's always trimmed her wick pretty darn close to the wax as she always knew the 1/4 inch rule. The there's me who never even knew to trim wicks until a few years ago when a friend of mine, who sold Gold Canyon, said I was supposed to.

Definitely on fragrances sometimes needing different wicks. I always start out testing with ECO-16 as that seems to be a pretty good starting point. My 70/30 soy-paraffin candles use ECO-16 wicks and just that little bit of paraffin does enough to make the ECO-16 wick burn just right.

Edited January 16, 2023 by AudraT

[AudraT]

On 1/13/2023 at 11:29 AM, kandlekrazy said:

Did you check the lot#'s on those bags? one may have been a different lot and wax is varying so much these days.  It does sound like sink holes in the wax.  You can poke around the wick and repour or heat gun to help with sink holes.  Cold weather can also factor if the candle cools unevenly sink holes are likely to develop.  A box over the candles while cooling may help.

I don't think it's sink holes. It's extra wax hanging up along the sides of the jar because the melt pool no longer melts to the edge of the jar. I responded to everyone's post though explaining that it was inconsistent wick trim lengths / improper wick size that was causing the random tunneling. I did want to comment on your experiences with colder weather though and acknowledge that you notice a difference with your burning when the seasons change. I do think colder weather does play some part with my candle issue, albeit it is a very small part.

[NightLight]

CD 24 can work 3 inch container BUT burn all the way down if container is more than a couple inches in height that CD24 might change to CD 20! For example I have a tin CD24 soy wax that works great with that size all the way down, but the height of tin is not more than 3 inches. If the tin was taller I would know that the CD24 would burn hotter deeper in tin.

[AudraT]

11 hours ago, NightLight said:

CD 24 can work 3 inch container BUT burn all the way down if container is more than a couple inches in height that CD24 might change to CD 20! For example I have a tin CD24 soy wax that works great with that size all the way down, but the height of tin is not more than 3 inches. If the tin was taller I would know that the CD24 would burn hotter deeper in tin.

This is all very good info I am getting from everybody in this forum. I am so glad I finally found this place as YouTube videos and blog posts usually just give kind of generic information.

[AudraT]

21 hours ago, TallTayl said:

Do Be aware, most people don’t perfectly trim wicks before lighting.  The average person doesn’t trim at all, and expects the candle to just ”work”. Nobody in my own family trims a wick before lighting despite instructing thousands of people to do so over the past decade and a half of selling candles.
 

  If you wick for a burn based on a  perfect trim you may be getting yourself into a pickle.  Cd24 is a pretty big wick.  Make sure to powerburn and take temps as you burn the candles.  The container temps will often rise sharply during the last half.  Tunneling will be the least of your problems on that case. Each fragrance may need a different sized wick also, depending on the aromachemicals and diluents in the fragrance.  It’s rarely a one size fits all with soy.  

By "power burn" do you mean just let the candle burn for as long as possible (i.e. don't blow out after 4 hours)? What is the ideal temperature for soy candles? I've never actually measured the temperature of my candles. I just size the wick so that the melt pool is a consistent 1/2 inch deep and the wax melts approximately 1 inch in diameter for every hour. So, if I have a 3 inch diameter candle I want the melt pool to reach the inside diameter of the jar in approximately 3 hours.

[TallTayl]

A powerburn is a very long, full day+ burn as if a customer lit and forgot it was lit. It can be performed when perfectly trimming, and should also consider imperfectly trimmed wicks. Customers will never trim perfectly even if they promise they will.  
 

max temp for containers according to the UL testing range in the US I have researched state 125*F for metal and 140-145*F for glass. You can Google candle tests for various recognized resellers, like Disney, Home Goods, etc and see the test results in PDF format. It is a very good set of tests to learn to perform. The Tests also reference ASTM, which has been discussed many times here and on many presentation type slide decks easily googleable.
 

somewhere, some time ago, someone started a discussion that ASTM limits container temps to 175*F.  I purchased the ASTM standards doc for candles, and have directly contacted ASTM to ascertain the temp and learned there is not one stated by them as claimed. This does not mean there is none in your country, it is just not ASTM standard. UL in the US is the referred to source.
 

Related topic: I encourage anyone burning and selling candles to learn the ASTM standards. If anything happens to a  candle while someone burns it, the best defense is to follow the published standards. 

[AudraT]

20 minutes ago, TallTayl said:

A powerburn is a very long, full day+ burn as if a customer lit and forgot it was lit. It can be performed when perfectly trimming, and should also consider imperfectly trimmed wicks. Customers will never trim perfectly even if they promise they will.  
 

max temp for containers according to the UL testing range in the US I have researched state 125*F for metal and 140-145*F for glass. You can Google candle tests for various recognized resellers, like Disney, Home Goods, etc and see the test results in PDF format. It is a very good set of tests to learn to perform. The Tests also reference ASTM, which has been discussed many times here and on many presentation type slide decks easily googleable.
 

somewhere, some time ago, someone started a discussion that ASTM limits container temps to 175*F.  I purchased the ASTM standards doc for candles, and have directly contacted ASTM to ascertain the temp and learned there is not one stated by them as claimed. This does not mean there is none in your country, it is just not ASTM standard. UL in the US is the referred to source.
 

Related topic: I encourage anyone burning and selling candles to learn the ASTM standards. If anything happens to a  candle while someone burns it, the best defense is to follow the published standards. 

Very useful. I will check this all out.

[TallTayl]

Here is a link to another ASTM/UL temp discussion

 

[NightLight]

If you have a deep meltpool at top of candle after three hour burn, by mid candle that meltpool will be much deeper, so you need to adjust wicking. That’s the candlemaking torture of finding the right wick!

[Crafty1_AJ]

Soy burns slower in cold temps.  It's just finicky that way.  I have soy candles that are perfect in warmer temp rooms, then winter hits and they threaten to tunnel.  Personally, I trim the wicks shorter in the warmer months.

[AudraT]

So, I just so happen to come across this post today and I realized I needed to update it. Before, I thought I had underwicked a couple of my candles and I needed to go up one size. I've since learned that's not accurate. What really happened was the reason why the candle at work started tunneling was because winter had hit and the front door to the office was constantly being opened and closed. This resulted in a cold draft hitting the candle all day long. That's why it started tunneling. And my independent testing on two of my fall candles... my original wick (ECO 16) was actually fine. It wasn't to small. What seemed like tunneling in my controlled environment testing was actually just the wax hanging up and waiting to be burned down with future burns. So, I haven't needed to change any wicks yet.

What I'm really working on now is whether or not I need to size down (down to ECO 14) for some of my candles. I might need to, especially with my 52% soy/48% paraffin candles. The FO really does seem to matter. One candle fragrance definitely tunnels with the ECO 14 wick while other candles are just on the border of do I / don't I need to size it down? This is tricky.

[TallTayl]

@AudraT fragrances make a HUGE difference, don’t they? The solvents used can dramatically change a burn in the same wax, and between different waxes.  This is one of the reasons I’ve begun to work more closely with the fragrance labs we use for our own candles.  

[AudraT]

On 1/16/2023 at 6:36 AM, NightLight said:

CD 24 can work 3 inch container BUT burn all the way down if container is more than a couple inches in height that CD24 might change to CD 20! For example I have a tin CD24 soy wax that works great with that size all the way down, but the height of tin is not more than 3 inches. If the tin was taller I would know that the CD24 would burn hotter deeper in tin.

Hello. I'm curious what you would do in your hypothetical scenario where a CD24 wick burns properly at the top of the candle but you find it needs to be a CD20 for the middle? If you did size down by 2 whole sizes wouldn't you stand a good chance that your candle would tunnel at the top? Would you try switching to a different type of wick or something to correct this?

Just FYI, I never did switch to a hotter wick for my candle issue I had back in January. It's a long story but there was never actually anything wrong with the candle.

[bfroberts]

23 hours ago, AudraT said:

Hello. I'm curious what you would do in your hypothetical scenario where a CD24 wick burns properly at the top of the candle but you find it needs to be a CD20 for the middle? If you did size down by 2 whole sizes wouldn't you stand a good chance that your candle would tunnel at the top? Would you try switching to a different type of wick or something to correct this?

Just FYI, I never did switch to a hotter wick for my candle issue I had back in January. It's a long story but there was never actually anything wrong with the candle.

If it needs a smaller wick in the center, it really just needs a smaller wick. Don't get hung up on getting a full melt pool at the top. 

[TallTayl]

2 hours ago, bfroberts said:

If it needs a smaller wick in the center, it really just needs a smaller wick. Don't get hung up on getting a full melt pool at the top. 

Amen to that. 
it seems the definition of “tunneling” is different from person to person. 
tunneling, to me, means hang up that will never melt. Like the candle leaves an easily measurable even shell of wax from top to bottom. The shell is like a hurricane lamp candle.  You could pop a new candle right down the middle of a tunnel. 
 

“hang up” eventually clears as the candle burns safely from top to bottom.  If I had to measure, I’d say less than 1/8”- 1/4” thick and shrinks in height as the candle burns. The wax from the walls of the hangup slowly weeps down the glass exposing fresh scent to the flame with each minute.  This type of burn leaves the glass well within the temp safety standards, and doesn’t “burn out” the fragrance like a full, hot melt pool does. The candle smells as fresh on the last burn as it does on the first. 
 

While researching wick manufacturer technical documents I realized that their melt pool dimensions, flame height and rate of consumption rarely (IMO never) intend for full melt pools.  High end Candles I’ve loved to  burn for decades never reached full melt pool.  The wax gently melts from the sides into the pool.  Hang up slides down the glass during a burn leaving a squeaky clean container by the end without ever hitting a full pool. Those candles never produce soot during the longest power burns.  They are light and forget types without worry of a candle causing a fire from being over wicked. 
 

 

[AudraT]

Good info to know! I'm just trying to figure out if some of my para-soy candles need to go a size down or not.

I'm currently power burning three candles with the wick sizes I had expected. Candles are halfway down the jar, and they are doing fine so far. Past 4 hours and laser thermometer has the very tippy tops of the jars between 120 - 140 degrees. So, we'll see what everything looks like as we head into hours 5-8.

I've only sold about 2 of my candles online. The rest of my candles I've sold to friends, people from church, co-workers. I'm having my own candle party with friends and I like that I haven't expanded the candle portion of my business to far.

Edited May 10, 2023 by AudraT

[AudraT]

6 hours ago, bfroberts said:

If it needs a smaller wick in the center, it really just needs a smaller wick. Don't get hung up on getting a full melt pool at the top. 

That's good to know. I'm currently testing a candle with one size down from what I initially expected and it's taken absolute ages for the melt pool to get anywhere. I mean, it took nearly 4 hours for the melt pool to get large enough and deep enough to finally leave a descent scent throw. 3 inch diameter jar, melt pool was extremely shallow, much less than 1/4 inch, and the diameter of the pool was so small. At four hours everything is fine now. If the wick started longer, like 1/2 inch, then the melt pool wouldn't have taken so long to develop and the fragrance would have been stronger.
I'm going to continue testing to see how it functions deeper into the jar. It'll probably burn perfect. I think the fear is that people will become disappointed with the candle at their first burn.

[bfroberts]

46 minutes ago, AudraT said:

That's good to know. I'm currently testing a candle with one size down from what I initially expected and it's taken absolute ages for the melt pool to get anywhere. I mean, it took nearly 4 hours for the melt pool to get large enough and deep enough to finally leave a descent scent throw. 3 inch diameter jar, melt pool was extremely shallow, much less than 1/4 inch, and the diameter of the pool was so small. At four hours everything is fine now. If the wick started longer, like 1/2 inch, then the melt pool wouldn't have taken so long to develop and the fragrance would have been stronger.
I'm going to continue testing to see how it functions deeper into the jar. It'll probably burn perfect. I think the fear is that people will become disappointed with the candle at their first burn.

I know exactly what you mean. I wick consecutively and I used to fear customers would consider the candle a dud if they didn't get a big melt pool and a knock your socks off throw immediately. In my attempts to create a safe power-burnable candle, I found out that more conservative wicking truly does make a superior candle. One that burns cleaner and produces a more pure scent - from top to bottom.  I've never had anyone complain about lack of throw but I have had customers remark on how clean and "perfect" the candle burned from top to bottom. It took me a really really really long time (years) to get here