Lilyuq

Hi, all, I am new to C3 wax, so i am trying different pouring temp to achieve a smooth top without adding FO first. I tempered the wax, heated to 185F and stay for 5 mins, then removed from the heat and let them cool down for the whole night. The next day, I heated wax up to 185F again, and poured at 165F and 135F respectively, and cool down gradually in the preheated oven. But the tops of two candles turned out to be very similiar, both have shrink in the centre, and both have pattern just like turtle deck, no actual crack. Can anyone enlighten me what the reason might be to cause the shrink and such cracking like pattern. Thanks very much!