Question for a newbie: What type of wick would you recommend for the use of EcoSoya CB-Advanced Soy Candle Wax and 4 oz jar measured as Height of of jar is 2 -1/16 inches when measured with our silver plastic cap, and with the silver metal cap, the height is 1-13/16 inches. Candle Wick Cotton Core: 3.5", 34-40. or Candle Wick Zinc Core: 5", 51-32-18. What is the difference between the use of cotton and zinc? Thanks!