Hi!
I'm new to this board and just getting back into working with resin. I do have working experience with resins and fiberglass some years ago... Including homebuilt aircraft part fabrication. But there is always something new to learn and I'm excited to join in here.
In brief, I'm getting some good sized bubbles in castings made with Smooth-Cast 327 and green pigment.
The casting in question is Smooth-Cast 327 in a Mold Star 30 mold. It is dyed with So-Strong green.
My procedure: Apply Mann Ease Release 200 to the mold (let dry). Mix the resin, add the green then degass in a vacuum chamber for 2 minutes. I have a good pump that reaches 30lbs. I then pour a small amount of resin into the mold and slowly flow it around to line the mold with a thin coating. Then I slow pour to fill up the mold.
The casting is 2" x 5" in size and about 10oz in resin volume.
The final castings are consistently getting 1/4"-1/2" sized bubbles. Just a few. These are happening in the same general area each time, usually near a seam. They appear to be hollow bubbles. ??? I've done four castings now with the same result. I am not getting small bubbles, only these larger hollow cavity type bubbles.
FYI: I am also doing similar castings of two other molds and getting better results with only a few castings showing any large hollow bubbles. These castings are with So-Strong black and purple dye.
Could it be an issue with the green pigment?
Could it be an issue with the seam in the mold? Not closing tight enough?
Should I be degassing the resin in the mold instead of before pouring?
Or do I need to pressure cast? Which I would hope to avoid having to invest in...
Thanks for any and all suggestions.
Bert