Blood coagulatates when you have a blood type and you mix it with a blood type that is not able to receive it. Thanksss
This happens due to conversion of fibrinogen to fibrin in presence of air.
Coagulation. Human blood takes approximately 15 minutes to fully coagulate and separate into the serum and red blood cells.
Clot, or scab.
I am not an expert in blood but the reason why blood coagulates when dehyadred is because it dries up faster like a plants leaes when you don't water it.