I have been testing the wood wicks from soap and things. It crackles, low flame, strong scent throw and no soot or ashes. I use an 11 oz. straight sided tumbler that is just over 3 inches wide. The wood wick size I am using is the small. I am loving it. I do have it sitting on a large candle plate but so far I have not seen any sparks. I would recommend to label how to safely use them. The wax I am using is JBN's soy blend 70/30 wax. I saw some bad reviews on soap and things but I am not having any problems with them so far. I used over an ounce of FO. I don't even trim the wick when I relight it. I will trim it the next time closer to the wax the next time to see if it crackles more but it seems fine to me the way it is.