Metal Casting Zone

Who ever can help

So my very first sand casting last weekend. Cope and drag rammed well
brass melted ok.Poured well and filled the cavity completly Great Pretty happy with the result for my first try..." BUT " The finished casting has quite a few holes in the top surface. I certainly won't be able to file these out and polish up the top as I had planned. Could these holes be from .
Metal too hot.
Air not escaping because sand rammed too tight. Even thought I placed a riser at opposite end of mould.
Metal too cool, Poured brass at 970 Deg C but still not hot enough and lost heat when poured onto cold sand mould.
Metal no good ,used 50% new brass and 50% brass from a previous casting.
Poured metal too quick or too slowly.
I didnt coat the internal mould cavity with graphite powder as one book mentioned could this be a problem,causing too much metal turbulance

Would like a few answers if anyone could help please. Johncast Australia

Did you use any flux? I use a little Borax (20 Mule team)for Brass.
Did you cover the melt? Some people use glass, I like to use graphite because it isn't so messy.
You could take a thin wire and poke some vent holes across the top on the sand before you pull the pattern.

Show us some Pictures..

without some pics its hard to say but is it fresh sand??????that is just freshly made up sand and clay. when sand is fresh it can have impurities in it. im always amazed at the amount of fused sand i get after working with brass. my first batch of sand i made up was with kitty litter and i was always getting pits and holes in funny places. after i sifted my sand and removed the crap i get really good results.so it could be your sand.(it gets better with use!!)

JOHNCAST wrote:

Metal too cool, Poured brass at 970 Deg C but still not hot enough and lost heat when poured onto cold sand mould.


in place where I am working we pouring brass at 1040-1080

Hi
Johncast would like to say thank you all for your help. Jammer,xlchainsaw,crazymoulder
It is so great to have a form where you can ask questions and get answers quickly.My number one prob was temp, next time brass temp higer The brass was melted in a electric melt pot with cover, and flux was added and metal was stired twice with graphite stick. I did put a few holes into cope section for venting.The sand was old sand from a friends foundry , not new.
Sorry I didn't post photo shots ,I know it is hard to diagnose things without visuals I have taken shots on the camera and will try to figure out how to post these for a better appreasial of my attempts . At present the brass paperweight is now on the office desk.
Thanks Johncast

I use Photobucket. I upload the pictures as forum size, 640 X 480 (I think). Then I don't have to worry about a pictures covering the whole sceen. Here's my ugly brass casting. Incomplete burn out.

Greedo?