I agree in principle. But after years and years of casting ceramic shells I find it practically difficult. Our practice is to heat the shells to about 1200°. Shut off the kiln. The metal should be ready to pour at this point. So some care should be taken on your timing here. Metal and shell ready at same time. We will pull out the shells and put them in the sand bin. I suspect that they are something more like 600 to 800° by the time the metal gets in them. More critical is metal temperature control. You will have much better and consistent results with lower shrinkage if you monitor your metal temperature instead of guessing. Casting bronze. 2000°- 2050° Casting aluminum. 1,200°-. 1300°.

Lost wax style casting using pla or pvb works really well. We found that it's important that the filament have no colorant. And to use a very light infill.

I can help with gatting design if you're interested. Tips and tricks. Josh