Why are the wicks in 'gift' candles so bad?

sophiecentaur · Apr 10, 2023

Yet again I have lit a scented candle in a jar and the wick disintegrates faster than the wax level decreases. Result: the candle dies after just a few percent of its material is used.
If you go into a high church, you will see great big, thick candles that burn for days and days with healthy looking flames, right to the bottom, so somebody has got it right.

Has anyone else experiences (or even noticed) out solved the problem? If I could find a suitable wick material then I could easily sort out the problem by inserting a new wick down into the wax with a hot rod.

Baluncore · Apr 10, 2023

Look for a cotton string that has a soft, fine structure, with a greater section than the wick supplied.

You can buy packs of wicks on eBay etc. Twist two or three together to make a better bundle.

Make sure the wicks do not have a Pb wire, like some from China.

scottdave · Apr 10, 2023

Baluncore said:

Look for a cotton string that has a soft, fine structure, with a greater section than the wick supplied.

You can buy packs of wicks on eBay etc. Twist two or three together to make a better bundle.

Make sure the wicks do not have a Pb wire, like some from China.

Lead wire in a wick? I wouldn't have thought of metal wires in a regular candle wick. I've seen wires (maybe copper) in a Zippo wick, though.

Baluncore · Apr 10, 2023

scottdave said:

Lead wire in a wick? I wouldn't have thought of metal wires in a regular candle wick.

When candles were made by dipping, the Pb wire kept the wick hanging straight, or initially in the shape required. As the candle burned down, the lead evaporated in the flame, to become part of your lungs, bloodstream, and brain. That is why you should gift candles only to your enemies.

On the subject of sweet-scented candles, did Pb metal vapour smell sweet, or was that only the taste of Pb paint?

There needs to be some thermal transfer downwards to melt the wax near the lower exposed part of the wick. Convection takes the heat the wrong way. IR radiation has a limited possibility in the shade of the wick. Wicks are not thermally conductive, but a metal wire is.

I do not know what part the Pb wire played in thermal transfer. Maybe that could explain why the candles do not burn so well under EU RoHS regulations.

The wire selected must be non-toxic and burn or vaporise in a candle flame. Maybe it is time to try a tin or aluminium wire. We might change the colour of the flame by selecting minor alloy components.

There are also wooden wicks available, in the shape of a flat blade, made from dry softwood (splints?). I might give Cypress a try, as it dries quickly to become very light weight, with plenty of volume to wick wax. There still remains the thermal conduction problem. The wide flame should improve radiation heating, while the flat blade casts less shadow. Maybe balsa wood would work well.

256bits · Apr 10, 2023

It could be that the wick was dipped in wax, let cool, straightened to start the dipping process.
Which would actually be the case for a cotton wick, no core. The wick end will curl and burn off to keep the burn length consistent during the life of the candle.

Baluncore · Apr 10, 2023

256bits said:

The wick end will curl and burn off to keep the burn length consistent during the life of the candle.

The wick will burn off when there is insufficient wax to wet the wick. Ideally, that should happen as the candle wax is consumed progressively down the candle. But, there is a stability problem here if there is insufficient gain in the loop. When the dry wick burns off, the flame becomes smaller, less wax is melted and drawn in, so the candle fails to regulate, consumes its wick, then expires.

There must be an optimum wick to candle diameter ratio, such that the flame, burning above the pool, melts and pulls in wax that flows to the pool from the wall. That should self-regulate, since the wax pool depth adjusts the length of the exposed wick.

sophiecentaur · Apr 11, 2023

Baluncore said:

The wick will burn off when there is insufficient wax to wet the wick. Ideally, that should happen as the candle wax is consumed progressively down the candle. But, there is a stability problem here if there is insufficient gain in the loop. When the dry wick burns off, the flame becomes smaller, less wax is melted and drawn in, so the candle fails to regulate, consumes its wick, then expires.

Exactly. Am I unreasonable to expect the manufacturers to have been into that (albeit at a less sophisticated level) and to use appropriate wicks? Obviously (?) the wick diameter / volume determines the heat output of the system and if the wick is too large / rugged, the rate of wax burning could be too high and the jar could be full of liquid wax - not what you want.

I guess my solution is to eBay some wicks and to experiment - but really should it be necessary? Cheers for the inputs. chaps.

Baluncore · Apr 11, 2023

I suspect that the manufacturers use the thinnest wick possible, and don't chemically treat the wicks of the candles they make, because doing it properly would put up the cost of manufacture. They only need to get the next sale, so it only needs to look like a candle, the buyer then gives it away, not realising it was a non-functional token, so never making a claim against the manufacturer. The recipient leaves it around for a while, then passes it on or dumps it.

https://en.wikipedia.org/wiki/Candle#Wick

Wicks are often infused with a variety of chemicals to modify their burning characteristics. For example, it is usually desirable that the wick not glow after the flame is extinguished. Typical agents are ammonium nitrate and ammonium sulfate.

https://en.wikipedia.org/wiki/Candle_wick#Pretreatments_of_wicks

Virtually all wicks are treated with various flame-resistant solutions in a process known as mordanting. Without mordanting the wick would be destroyed by the flames and the flow of melted wax to the flame would cease. Beyond that, wicks can be treated with substances to improve the color and brightness of the flame, provide better rigidity to keep the wick out of the melted wax, and improve the flow of that wax up the wick. Common treatments are borax and salt which are dissolved in water in which the wicks are soaked.

sophiecentaur · Apr 11, 2023

Baluncore said:

The recipient leaves it around for a while, then passes it on or dumps it.

Dat's my boy! Been there, done that etc..

Exit through the gift shop.

Rive · Apr 17, 2023

sophiecentaur said:

Has anyone else experiences (or even noticed) out solved the problem?

What I often do (with candles worth keeping - the others just got melted down) is to tear a bit of rock wool from some insulation and form a small waterdrop-like shape of it, as a replacement of the original wick.

Since it'll just sit down to the bottom of the molten wax, some tries needed to get the size of the ball right (how much of it will be out of the wax). But after that it'll just sit there till there is wax around.

Willknot · Jun 13, 2023

Baluncore said:

When candles were made by dipping, the Pb wire kept the wick hanging straight, or initially in the shape required. As the candle burned down, the lead evaporated in the flame, to become part of your lungs, bloodstream, and brain. That is why you should gift candles only to your enemies.

On the subject of sweet-scented candles, did Pb metal vapour smell sweet, or was that only the taste of Pb paint?

There needs to be some thermal transfer downwards to melt the wax near the lower exposed part of the wick. Convection takes the heat the wrong way. IR radiation has a limited possibility in the shade of the wick. Wicks are not thermally conductive, but a metal wire is.

I do not know what part the Pb wire played in thermal transfer. Maybe that could explain why the candles do not burn so well under EU RoHS regulations.

The wire selected must be non-toxic and burn or vaporise in a candle flame. Maybe it is time to try a tin or aluminium wire. We might change the colour of the flame by selecting minor alloy components.

There are also wooden wicks available, in the shape of a flat blade, made from dry softwood (splints?). I might give Cypress a try, as it dries quickly to become very light weight, with plenty of volume to wick wax. There still remains the thermal conduction problem. The wide flame should improve radiation heating, while the flat blade casts less shadow. Maybe balsa wood would work well.

What about really thin twisted fibers of pine sap wood?

Baluncore · Jun 13, 2023

Willknot said:

What about really thin twisted fibers of pine sap wood?

Welcome to PF.

I think you will have to do the science experiment.

Thin twisted fibres may be unstable and need very fine copper wires twisted into the wick to give it stability and prevent curl. The wick is a fuel line. The copper will transfer heat from the flame downwards into the solid wax. That will melt the wax that will be wicked upwards to be burnt next. More copper in the wick will make a bigger flame, melting and burning wax faster. The fine copper will oxidise where it protrudes from the side of the flame and may add a green colour while it is being burnt.

Since a fine fibre with insufficient wax flow will be rapidly consumed by the flame, the borax "flameproof" treatment will be needed. The simple addition of cooking salt, NaCl, to the treatment will produce a more yellow flame.

Pine sap wood may make a good wick if it can be dried and treated. The presence of sap or oil in the wood fibres may block the flow of wax. I would consider vacuum drying and vacuum impregnation of the fibre.

sophiecentaur · Jun 14, 2023

Baluncore said:

Pine sap wood may make a good wick if it can be dried and treated.

Any wick needs to be able to resist burning away too fast or you have no wick. I would imagine that limits the choice of materials. An experiment is, as you say, probably the only way.

But I would expect candlemakers to have done all that already. (which was my original whinge)

Why are the wicks in 'gift' candles so bad?

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