Got my first brass mold a month ago, finally got a chance to use it. Quality looks great, I.e., tight fit, good alignment, lots of vent lines. However, I kept upping temperature and was still getting pronounced wrinkles at 25°C above my normal temperature for my old SAECO irons. Manufacturer FAQ states they are shipped without any preservatives. Any thoughts as to why? Alloy is 50/50 coww and soww. Pid is Celsius only.