Another way to get a core shot is to hand pour the belly cavities almost full, then add a contrast color by dipping a toothpick into raw colorant and adding a very small drop of color to the front edge of the belly color just behind the edge. Close the mold and shoot the top color.
I was messing around with this tactic using some left-over clear sparkle plastic and came up with these. Doing a core this way doesn't have an outstanding core color until the bait is turned so that you see more than the sliver edge. I've done other color combinations that really look neat.
Do as jerry has suggested and play with different core techniques using scrap plastic re-heats. Using the previous method I'd suggest using a more opaque plastic color for the core and a more transparent color as the shoot color so you can see what is taking place and where adjustments need to be made.
This plastic is a riot to toy with. I get to the shooting bench sometimes and just get lost in fiddling around with scraps and colors and different types of pearls/hi lites.
