Resin casting woes


Active Member
I made a Smooth-On Rebound 25 mold of a sphere to slush cast some hollow orbs. The end goal is a bunch of materia from Final Fantasy for an artistic display. I'm using 2 ounces of Alumilite Water Clear per 3" orb (I know it's not going to be totally clear, as I'm not pressure casting, but I just need it to be translucent) with 2 drops of Alumilite dye each.

My first two casts were perfect. The following ones? Not so much. (The last one is a bit crumpled because I got angry and smooshed it.. but you get the idea with the glob on the right side and very thin shell around it.)
materia-preview.jpgsupport.jpg2015-02-27 11.17.58.jpg2015-03-03 16.33.38.jpg

I used exactly the same technique for each cast: Heat the mold to 125 degrees as recommended in the instructions, mix dye thoroughly with part A, mix A and B thoroughly. I rotated the mold every 30 seconds (on 4 axes to ensure an even coating) on each cast. The first trials (red and blue above) I rotated for about 75 minutes. Some of my later trials I thought I might not have rotated them long enough, hence the clump in the middle, but even after rotating for 120 minutes (the recommended demold time for this type of resin) it still did the same thing. It doesn't seem to matter what color dye I use; in addition to the red+blue=purple, I've also used green and yellow to no avail.

Any suggestions? I've dropped quite a lot of money on this project (not only the resin and dyes, but an Arduino, LEDs, power cable, and even a new band saw to cut the MDF for the base of the display) and I'm a little desperate.