I've been playing with pairing brass for about a month or two and I don't add zink.... you can for sure have zink burning off and the more oxygen you have in the kiln is more vapor... if your Pouring in a graphite mold you're going to find the chemical white scale sometimes a yellow tint....
O hammered dog that is zinc oxide Now they say once it's cool you are safe to be around that garbage but I do not trust that.... Practice and preach double checked for your PPE and be sure you think 5 steps ahead rest respirator shield leathers. Also do a very very aware aware check on crucible for damages and defects..... The clean tool is a clean pool a slag off is a trash....
I've been using kinetic sand for my casting believe it or not it has done me great but.
To all the beginners like me do your research you can playou can play most of the way you're gonna pay...
Stay safe peeps and pour on