I've noticed this happening with my scented soy candles. They look perfect initially but after a few weeks this weird ring seems to appear around the edge of the candles. Does anyone know why that is or how to prevent it from happening?
This is called 'Frosting', and is an indicator that your soy wax is 100% natural! It is the natural crystallization of the wax. You can prevent this by playing with your pour temperature (only adjust in small increments), and making sure the place you leave them to set has a stable, warm temperature. Check that your wax's manufacturing date isn't older than six months, because aged wax will almost always react like this!