Starting out in the candle business can take a lot of time, testing, and patience. There are a lot of habits to learn and obstacles to get past - even after you've found your market and decided on a design!
In this post, we'll help you understand one of the most common candlemaking problems, and share some ways to avoid it - tunnelling.
Tunnelling can affect all candles of any shape, colour & size
What is tunnelling?
Candle tunnelling is the phenomenon of a candle, when lit, melting only through the centre of the candle - without melting the wax surface evenly.
It results in a border of solid wax around the edge of your container, and continues to worsen over time.
A "sinkhole" refers to bubbles or gaps that are formed inside the candle, below the surface, as the candle cools and sets. These bubbles create a trap of air under the surface of the candle, which are then revealed during burn time. This can result in an uneven melt pool, as the liquid wax fills the air pockets as the candle burns.
A deeply tunnelled candle
What causes tunnelling?
Tunnelling is a common consequence of using a wick that is too small for your chosen vessel - in other words, the candle is "underwicked"
The wick as a consequence produces a flame that is not strong enough to melt the full width of your vessel.
Instead, the melt pool's diameter is smaller than needed and the candle surface will unevenly and only partially melt. Overtime, the candle melt pool and flame will continue to melt with a reduced diameter, causing a small, vertical "tunnel" into your candle.
Another important cause of tunnelling is overwicking.
This phenomenon is rarely discussed in candle-making circles, however overwicking can cause a situation in which your candle is burning too quickly to achieve a full melt pool.
This will appear, on the outside, as very similar to an underwicked candle - which is why it is difficult to spot.
Can I fix tunnelling?
Unfortunately, as tunnelling is a consequence of improper candle-making, there is no way to fix the issue once it has appeared.
This is the reason wick and burn testing is so imperative in candle-making. Testing is the only way to ensure you are creating candles with optimal and perfect burn.
How do I avoid tunnelling?
In the case that you are confident in your wick and vessel choice, but are still suffering from tunnelling candles, we suggest practising healthy candle burning and ensuring you allow the candle to achieve a full melt pool on your first (and subsequent) burns.
It is to allow your candle to burn long enough that the entire surface of the candle is melted. This generally takes 1-2 hours, depending on size and shape.
This tip is especially important and it speaks to the candle's "memory" and will influence future burns.
This is due to candle wax's sensitivity to temperature. Despite its appearance, candle wax does not solidify immediately and instead continues to solidify as the weeks and months go on.
For this reason, candle wax that was melted previously, and then cooled, will generally be softer than candle wax that has not been previously warm.
Therefore if you only allow for a small melt pool on your first burn, subsequent burns will follow suit as the "softer" wax from your previous burn requires less energy to be fully melted.
The surrounding wax will therefore be "hard" in comparison and take longer to melt - therefore creating a barrier that your melt pool cannot get over.
Have a candle that's tunnelling?
Every Vuur candle undergoes strict quality-control and procedures before leaving us, and we will never send incomplete or underwhelming candles to our clients.
We want you to trust your product, and if you would like to discuss any of the above in more detail, please get in touch with your Account Manager and they'll be happy to discuss further!