Interesting discussion. For most hobby blacksmithing and general forge work, propane remains the practical choice because it's widely available, affordable, and burners are typically designed around it. Propylene can offer higher performance in some applications, but it usually comes with higher fuel costs and may require adjustments to get the best results. Unless there's a specific need for the extra heat output, propane is often the better balance of cost, availability, and ease of use. _____________________________ Alexandra from Ci Analytics