Casting second flask

 I made two flask for casting. When everyone was finished with casting I had get the metal extra from other students so that I can cast my second flask. One of the metal was not cleaned properly it had some dried investment. I went to the melting area to melt metal, my problem was I can see that the metal is melting but there is this tree which wasn't melting. When I get the flame closer it floating and not melting. I realized it was investment. The student who was helping me to cast gave me the piece of wood to take out the investment. While was I doing that she take out the flask to the casting machine.  The machine wasn't suction by that time I was panicking. The metal was boiling because it was over heated. I had to move away the flame to let it cool. While waiting for the casting the machine to suction, I was heating the ingot so that if fails to suction, I was going to pouring the metals in the ingot. Luckily the casting the casting machine suctioned the flask, I poured the metal and the tree came out well as you can see figure 1 below 

Figure 1