I am new to this community and I joined because I need advice. In the last five months I started casting. I have been successful at casting brass but am finding issues with casting sterling silver. I follow the same steps that I do with brass - but keep finding flaws in my castings when going to polish. Cracks, little holes.
Here is the process I am following.
ultravest investment - following recommended ratios
vacuum bubbles out, fill flask, vacuum again.
let sit for at least 2 hours
put in kiln -
full speed up to 300 degrees for 4 hours. pull tray with wax out, close kiln.
ramp up 225 degrees per hour until 1350, hold for 6 hours
full speed down to 1000 degrees, hold for three hours till ready to cast.
melt sterling to 1825 (i have used straight sterling casting metal and also sterling sheet metal scrap with no solder etc. and casting media)
pull flask, place in vacuum, turn on vacuum then pour metal.
continue vacuum for 90 seconds.
pull flask and let rest with charcoal block on top of button for 15 minutes then quench.
any advice would be greatly appreciated.