Yes the ceramic coatings are the shell for the investment casting. They usually dip in fine several timers, then in coarser material for added strength on the form. When you do precious metals, they recommend a centrifuge to avoid porosities, but I have not tried that, and it seems like a good flux would lift out problems well. I have been watching you pour, and you are ahead of me on videos! That I have NOT tried yet! Keep on pouring! :)