So I'm fairly new to metal casting. I'm 16 and I got some stuff to make a foundry for Christmas and the extent of my knowledge is YouTube videos. I have done some minor lost foam castings but we ordered some petrobond II recently. I have made a casting flask, but I need to have some questions answered before I start. I noticed that when people make a casting that the petrobond appears to be burnt around the metal like in this photo. https://www.google.com/search?q=petr...&dpr=2#imgrc=_
Does the black petrobond need to be scraped away and put in a separate pile?
Can the black petrobond ever be recovered?
Do I need vents for air to escape when I pour metal with petrobond?