Do you notice black stuff on your candle jar? Are you wondering why it's doing that? Well, I'll tell you why!
The main reason why this is happening is because trim is too long and you didn't trim your wick. This is called soot, soot happens when candle is burning improperly caused by untrimmed wick
Is it unhealthy? No, it doesn't impose any health risk.
So, trim your wick before burning the candle again. It'll help reduce soot and it'll make your candle last longer.