The finning is due to the investment not solidifying properly and micro-cracks forming. Did you make sure you kept it undisturbed for two hours to allow it to reach a high enough green strength?
Also, how long did you wait from when you invested to when you burned it out?
I don’t see finning unless I rush the process or disturb the main sprue before it hardened enough.
Thank you for providing your opinion, but I think I found the problem. My problem is that I do not put the flask at a temperature of 125 degrees Celsius to evaporate all the water so that the investment is more solid to withstand the expansion of the resin and so that the water vapor does not cause the collapse of the investment when the temperatures rise