To fight bubbles embedded in the casting I got a spray bottle to apply VacuFilm on the wax models more evenly - this worked and I got a thin mist layer instead of large drops as when using the brush.

I also got a new large vacuum chamber for degassing before and after investing the wax model. I tried to do that with the vacuum oven for a long time (it was large enough), but after using it for wax, it no longer pulls full vacuum unless it's hot. With the new chamber, time to full vacuum is short enough that I can vacuum twice, all while agitating aggressively with the vibratory tumbler.

The resulting casts no longer have bubbles stuck inside concave geometry. There are actually a few bubbles on convex geometry (perhaps just a spot I missed with VacuFilm) but those tend to be simple to just grind away.

The last problem are the inclusions - and I noticed that making sprues that are bent several times before reaching their target may be the answer. Kind of like the bent leg of a kitchen sink where all the garbage ends up, they seem to catch inclusions before they get to sensitive geometry. The model that had two of these bends next to each other had the least inclusions of the entire batch (almost perfect).

Lastly, I automated the investment/water weight calculation to save myself some time & trouble. I wanted to experiment with Preact and Recompose for a while for building small but potent web apps, and I also wanted to see how simple it would be to build a site that's pre-rendered while being very interactive, and hosted in a static S3 bucket on the Amazon cloud. I published the app and it works amazingly well - now I am taking a UI design class and learning Sketch to design the graphics to go with the functionality

Of course I will mostly be using it on my phone, so I have the mobile comp as well: