Soy wax is the most popular natural material among hobby candle makers in recent years. It owes this popularity to its excellent properties, but there are a few problems that are particular to this type of wax, one of which is that it is difficult for it to solidify if not poured in the right conditions.
Too many candle additives
Adding too much additive to the melted wax can delay or even prevent it from fully solidifying. Most waxes, including soy-based ones, can absorb up to 10% of their own weight in some non-wax additive without losing their ability to solidify.
For candles, there are two additives that can prevent complete solidification. One of these is the liquid colorant and the other is the fragrance. If you follow the dosage amounts specified by the manufacturers or in the candle recipes, solidification should not be a problem.
Fragrances can also cause problems if they are not properly mixed with the wax. They can then form individual droplets and can sit on top of the wax, preventing it from fully drying.
This problem can also be relatively easily avoided by mixing the liquid ingredients properly, but remember to be careful with the liquid wax to avoid stirring in air bubbles.
There is a reason why the expiry date is indicated on the waxes. If you use expired waxes, they can impair not only the appearance of your candle, but also its burning properties in many ways. The composition of soy wax is very similar to that of household oils, so it can go rancid too after expiry. It is therefore very important that the wax is stored properly, out of sunlight, in a cool place and only used before its expiry date.
It is good practice to buy only as much wax as you will use in the foreseeable future, so that you do not have to worry about having to throw out expired raw materials.
If for some reason you cannot find the expiry date on your wax, you will still be able to tell that it has expired relatively easily, as it will lose its white colour and become transparent instead, and it may also melt at room temperature.
As soy wax has a relatively low melting point, make sure that the room where you leave the freshly poured candles to dry is cool enough. While it may be tempting to open a window to speed up the drying of your candles, avoid doing so, as if the temperature is not even during curing, the soy wax candle may develop a phenomenon known as frosting, which will spoil the appearance of your candle with white, crystallized wax chunks.
As we have seen, there are a number of circumstances that can lead to a candle not solidifying properly, but as the above may have shown, if we are careful, all of these can be easily avoided.