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Why does my soy candle have a lumpy, curdled top?

Posted on September 12, 2022

Although making soy candles can be fun and very rewarding, sometimes it can be the most frustrating and stressful hobby or business.

An ideal candle will have a smooth finish to the top, no wet spots, no frosting and smell amazing.  Many times this can be achieved purely by luck and accident, but it’s when it starts to go wrong, that your experience and knowledge as a candle maker comes into play.

 A lumpy, pitted, holey, or rough curdled top on your candle can be due to a number of factors.                                      

Pour temperature 

 Pour temperature is of huge importance if you want your candle to set right. 

You might get better results pouring one particular fragrance 5 degrees hotter than recommended, but another fragrance requires 10 degrees cooler. 

Keeping a detailed diary is a must.  Work in increments of 5 degrees until you find that sweet spot.  Also remember what works for someone else may not necessarily work for you.

Ambient temperature

This important factor is often overlooked. 

Many candle makers, even the most experienced, often overlook the weather conditions and ambient temperature of the room they are pouring in.

 Seasonal variations have a huge impact on candle making, particularly in Australia where you have extremes of heat and cold.  Soy wax does not like humidity, air conditioning, freezing cold weather or drafts.  Sometimes it is easier looking after a baby 

Your room should be comfortable, around 25 degrees.  Avoid fans and air conditioning.  Pour slightly hotter in winter than in summer.


This is often the  main culprit.  As wax is manufactured and packaged into boxes inside plastic bags, it doesn't have the correct amount of time to cool down sufficiently before being sealed up.  Even if it does, being shipped around the country, shipped overseas in tightly packed containers, stored in warehouses, shipped in hot trucks to customers, then stored who knows where on arrival, the wax can often 'sweat' in the plastic.  This moisture can make the wax sticky and cause your candle to 'curdle' upon setting.  It is really important to open your wax and let it air dry before use particularly if it has been stored for awhile.

 Fragrance & Essential Oils

These are again often overlooked.  Some fragrances can contain certain ingredients that react with the chemical structure of soy wax.  Fragrances that contain vanillin’s or essentials oils like rose geranium and lavender are quite notorious for ‘curdling’ the tops of soy candles after they have set. 

This can be overcome by pour temperature adjustment, however if this still does not work then adjust the percentage of FO or EO you are using.

Lumpy top after burning        

Now this is normal!  Pure soy, with no additives, will be rough and cratered when it resets after a burn.  It is completely normal and is an indication that your wax is 100% soy.  If it sets smoothly then your wax has additives in it, most likely paraffin wax, to prevent these tops.  


In addition to temperature, moisture and fragrance, other factors that can contribute to issues with soy candles include the type and quality of wax, wick size and placement, and the container or mould used for pouring. It is important for candle makers to experiment with different combinations of these elements to find what works best for their particular setup and desired outcome. Keeping detailed records and taking notes on each batch can also help identify patterns and troubleshoot issues as they arise. With practice and persistence, even the most frustrating aspects of soy candle making can be overcome to create beautiful, fragrant candles that bring joy to those who use them.

  A Clark