The TCR wick is made from pure cotton intertwined with a twisted thread of paper. No chemicals are used. The TCR wicks are not bleached, nor treated with any substance such as chlorine. The excellent burn profile prevents from mushrooming and sooting and minimises smoke. Top quality cotton is used in the process and the core structure of the wick is surrounded by an external supportive jacket. The TCR wick works best in natural vegetable waxes. Wick size guides: 35-40mm: TCR 18/10 40-45mm: TCR 21/12 45-50mm: TCR 24/12 50-55mm: TCR 24/14 55-60mm: TCR 27/16 60-65mm: TCR 30/18 65-70mm: TCR 33/18 70-75mm: TCR 33/20 75-80mm: TCR 36/20 80-85mm: TCR 36/22 85-90mm: TCR 39/24 Please note that this is only a guide, what works for one wax, fragrance oil and container combination may not work for the next. Please make your own tests and take this as a rough guide only.