Today we'll talk to you about an effect that many chandlers in our community have called 'curdling'.

We are going to show you what causes this effect and why it might happen.

This is different to the process that happens when your milk goes sour.

The 'curdling' effect that you might have experienced is not actually curdling at all. What you are seeing is in fact a temporary phase change that occurs when a small amount of wax changes from liquid to solid.

Why does this happen?

This happens because the fragrance oil is at a lower temperature than the liquid wax. When the oil is added to the wax it cools the wax around it, causing the wax to change from liquid to solid.

However, because the bulk of the wax remains at a high temperature, the small lump of wax will melt again very quickly.

What should I do?

If you notice this ‘curdling’ effect happen during your wax melt or candle making process, don’t panic! Your fragrance oil or wax have not gone off. Just give your wax a stir and watch as the lumps start to dissolve.

Let’s experiment

We moved to the lab to experiment with fragrance oil temperatures.

We are going to do three experiments where the only variable is the temperature of the fragrance oil.

Experiment 1 – Heated oil

We heated a fragrance oil slightly to see what effect this would have on our wax. We noticed that no curdling had occurred as the fragrance oil was at a higher temperature and didn’t cool our wax.

Experiment 2 – Room temperature oil

We took the fragrance oil that has been stored at room temperature and added this to our wax. We noticed that even the room temperature oil was cool enough for the 'curdling' effect to occur. Small amounts of the wax started to turn back into a solid and this can be seen as lumps in the liquid wax. These quickly dissolved again once stirred in the hot wax.

Experiment 3 – Cool oil

We cooled some fragrance oil in the fridge till it was at a low temperature. We then added this fragrance oil to our hot wax. This showed a more dramatic version of the 'curdling' effect.

The lumps will quickly dissolve once stirred. This will pour and set perfectly normally.


Again, if you notice this ‘curdling’ effect happening to your wax when you are making candle or wax melts there is nothing to worry about. As we have seen in our experiments, this is a purely temporary change that is quickly resolved by mixing your wax.

We hope this has been able to clear up any concerns you might have had about this effect.