That is interesting that they state zinc burns hotter. In my testing and in everything I have ever read it states zinc burns cooler. That is why I didn't use zinc when I made soy candles, I needed a hotter burning wick. I also noticed in my testing that I usually got more soot or mushrooming when I used zinc wicks. That could also be the specfic type of wax I was using in combination with the FO's I tested. I even tested the so called Low Smoke/soot zinc wicks with the same results. There are so many components that factor into each individual candle. JMO but it bugs me when some companies state that their candles are completely soot free. Any candle if burn improperly can produce soot. I tested this with a candle I purchased from one of these companies that claim to be soot free. I didn't trim the wick and sure enough I had soot on the sides of the jar.