Metal Casting Zone

the answer john may be the brass itself??? maybe try a different brass mix????

Try a simple test first, put some flux on one of the brass strips you are melting and heat the underside with a torch and watch what happens. I have also read that flux eats up crucibles but I dont feel this is the color you are getting on your parts, it looks like flux to me. Pickleing the brass and cleaning it before melting makes a heck of a difference! once i started doing this my parts have come out incredibly clean with no residue or spots. I have been melting old propane tank valves.

Hi Xl and A1

Interesting that you both mentioned these areas to look at. I have been hitting the books a bit these last week to see where I can change my procedures to improve my result. Yes XL the brass is one area I think I suffer, the alloy is not the best ,,scrap brass sheet, rod tube wire etc scrap. some of the thick rod I have I think is a good alloy and will use this in next casting run...I used the rod brass before in earlyier casting I did and I think it contributed to a cleaner casting (Which is the photo on the bottom of my profile page if you look.)
Cleaning the alloy first is a good point A one, and I have the pickel soluition availiable here to boil the brass up before the melting. What temp do you melt your brass A one??? I melt and cast at 985oC on this last casting ,and flasks at 620oC but think I may still be requiring a hotter melt 1020oC for the brass and maybe a cooler temp for the flasks, Say 550oC .But I cast with a flask at 550oC last year and it didn't fill completely.

Should I still sprinkle borax into the metal when I melt,? one book mentioned not to flux brass in a graphite crusable. I am still toying with changes. Thanks to all who have posted replyies to help, much appraciated...JOHNCAST

with my brass castings when I used the borax as flux I got what looks to be an exact match of your problem. I have since quit useing the flux and my castings are clean and bright.

Well dosen't this speak for it self ( No Flux) needed. and after thinking about things I did flux these casting items with a good sprinkle of flux. Maybe the wrong thing to do...

It definetly was for me. My readings all say to sand blast used brass before casting, pickeling is much cleaner though.

dont flux your brass! every time i did it ended up a mess!!!!since i quit fluxing ive had nothing but success! most of my brass gets machined so i dont really know how it would be say as a figurine??