Understanding Curing Time in Candle Making.
A lot has been said online and in forums over the years about how long you should leave your candle to cure for optimal scent throw. This blog aims to enhance your understanding of the process as we understand it.
Candle Crystallisation
Candles go through a two stage crystallisation process as they cool after pouring. The first stage of cooling is when the wax turns from liquid to solid which is easy to see. What is harder to see is the second stage of the crystallisation process where the newly solidified wax fully cools and hardens, over time a crystalline lattice is formed containing the fragrance molecules within it. It is important to note that fragrances do not chemically bind to waxes, they are carried in suspension and are trapped within the crystal lattice. This cooling and crystallisation process is usually complete within 48 hours with the lattice structure remaining stable at this point. This is why we suggest that vegetable waxes, especially temperature sensitive examples such as RCX are stored in a temperature controlled area for the first 48 hours after pouring. It is for this reason that we have previously stated that this is the minimum time before you could burn a candle as the structure is fixed and will not change significantly after this point.
What is going on?
However, while the burn performance will not change after this time, the performance of the candle when it comes to scent throw can change and improve over time. This is referred to as curing time.
It has been anecdotally noted from various sources both online and in our own subjective experience that both hot and cold fragrance throw can improve markedly over this curing time up to around 2 weeks.
There are a number of different scientific hypotheses regarding why this is the case, such as fragrance migrating under diffusion pressure towards the top of the candle over time, or fragrance being more evenly distributed in the wax crystal matrix over time giving more consistent scent throw.
None of these hypotheses have been investigated or proved sufficiently enough for us to state which (If any) is correct. However, we and the community have found anecdotal evidence that suggests that while we may not know the mechanisms that cause this, it is good practice to allow a candle to cure for between 10 to 14 days (2 weeks) to give the most optimal subjective scent throw.
So, going forward, we are recommending that our vegetable waxes be allowed to cure for 10-14 days for optimal scent throw performance.