I tried to cast a gudgeon from a pattern I had made during class, but it failed. I'll show a photo later. I think I just choked and stopped pouring before it was full.
So my first attempt at home was going to be a re-try of that.
The 2-part mold or flask and the pattern.
[IMG]
IMG_0828 by
Michael Owen, on Flickr[/IMG]
You pack the bottom half with sand. In class, we used Delft Clay which is even finer but costs twice as much.
[IMG]
IMG_0829 by
Michael Owen, on Flickr[/IMG]
Then press the pattern into the sand about half way, then give the surface of the sand and the pattern a dusting of talcum powder.
[IMG]
IMG_0830 by
Michael Owen, on Flickr[/IMG]
Then put the top half of the mold on and sift sand around the pattern and slowly pack it in really tight. I flatten it smooth with a joint knife.
[IMG]
IMG_0832 by
Michael Owen, on Flickr[/IMG]
Failure! Even before the pour! I had a bit of trouble in class with this form as well. I think that the sand/clay is amazing and sticks like it's supposed to, but having those two long, tall arms was asking too much of it. Sorry the photo is blurry, but basically, within the arms, the sand didn't part properly.
[IMG]
IMG_0833 by
Michael Owen, on Flickr[/IMG]