I too am having difficulty getting the vacuum casting down. Would
appreciate any tips, feedback or suggestions. Would be happy to send
an image of last nights casting tree to see if it is my spruing.
Last night was about my 20th casting attempt. Teaching myself
everything from books, videos, Utube and here.
Working shop temperature is 38-41 F if that makes a difference. Yes,
the F is for farenheit. It is winter here!
Satin Cast 20
12 hour burn out with 60-90 minute hold at 1,000 degrees prior to
Electromelt at 1,830 degrees and holding about ten mintues to be
sure the crucible is hot all the way to the pour spout
Vacuum is about 24-25 drawdown when I pour.
About 15-20 seconds from the time the flask is placed on the pad to
pour. So maybe flask internal is cooling to 950?
Tonight I will try bumping temps up to 1,050 and 1,850
I am getting incomplete fills. The branch ends are rounded off. Bail
loops on pendants do not fill at all. Some pieces break off the
branch as being brittle. Flask size was 3x5 and I use a wet paper
towel between the flask and the silicone pad as that has increased
I am using 1/3 old and 2/3 brand new grain. Allowing to air cool 3-5
hours (12 last night as it was late) and breaking out the investment
by hand with an awl, tiny screw driver and tooth brush.
Last nights cast I had two pieces almost complete at the base
towards the button. The day before it was two pieces at the very end
of the tree, but I had a vacuum problem that day.
The flasks are sanded as is the investment. I am using four brass
rods on the edge and leaving BE-1 inch of investment on the pull
side. I am treeing a mix trying to find the sweet spot for something.
Heavy pieces seem to fill better than the light pieces.
My first attempts were just one piece and in spite of all the
mistakes I was making, were ok even based mostly on gravity. I did
not know about the red silicone gasket sequence, vacuum importance,
seal importance, bubbles, etc.