The mix ratio of water to powder has to be exact, no more adding
just a little more water to make it easier to pour.
Well, George, and all, I’ll temper this a bit. We use Satincast 20,
BTW, and always have. The mix of water to investment only needs to
be within certain limits, which, as someone else said, is like crepe
batter or thin pancake batter. There is advise out there to make a
thinner mix (like crepe batter) for finer pieces and a little
thicker for heavier work. We use measuring cups and aren’t
especially critical with it and get fine results for decades now.
What IS very, very important is that you mix it to death. Mix it
till it seems mixed and then mix it some more. It needs to be
There’s nothing wrong with ramping temperatures - professional
casters do it routinely. Our kiln is on a timer and it just clicks
on at 1AM, full temperature (from a cold start, of course). Again,
for decades with no problems. It’s not really critical - it is more
so if you’re casting 50 flasks. Certainly NOT ramping temperature is
not the reason for the cracks in this thread’s casting.
The recommendation is to let flasks set for at least two hours. If
you violate that you’ll have nothing but trouble. Ours set for 6-7
I can’t say for certain the reason for the cracks, not having been
there and not watching the process. I can say that I’ve had
overheated flasks in burnout - from a dead or dying rheostat - and
had that very problem as a result, though.