Why candles change colour!

 Have you ever had a soy candle change its aesthetics once lit?


Ultraviolet (UV) effects are commonly associated with candle development. The most frequent problem is discolouration of candle colour due to the ultraviolet effects of light.  This often occurs when candles are left for prolonged periods of time in UV light. If you have an un-coloured candle, once exposed to UV lighting, the candle will likely change to a yellow colour.  Some fragrances react differently and more aggressively than others, some get an ever so slight yellow, while other go bright yellow.

However, an often missed assessment of candle colour discolouration is caused by oxidation. Oxidation is a chemical reaction that waxes and other organic materials go through when the wax is overheated - it affects aroma and colour. 

Always select heating equipment that provides an even distribution of heat with tight temperature control to prevent overheating. Never use direct heat or a microwave. 

I have also found dark fragrance oils, usually strong yellow, orange or amber (Nag Champa is a good example) when incorporated at 5% or higher, can add significant colour to a base, making a blue into a green, or a white into a yellow, green or grey.

Other contributing factors can be stray metal contamination (such as rust or iron) on the candle wick, candle tab, candle processing equipment or candle stirrers.   

Avoid the use of copper, brass and their respective alloys in wax storage to avoid catalytic oxidative effects.

Never heat soy wax directly over heat or in a microwave as it will change the waxes chemistry.  Aside from discolouration, overheated soy contributes heavily to bubbling, frosting, wet spots, lumpy tops and poor scent throw.

Store candles in a dark cool cupboard and only bring them out to burn. If you plan to sell your candles, look at using a combination of UV inhibitor and sealed storage options to increase the longevity of your products.

Happy Candle Making!