This is my solution for green.. (blue should work as well- though I never have tried it)

Definitely go for the hard brine. Add powered milk to the brine which will help set the scales. Then add food coloring. Keep the bait in the brine and cool for a couple weeks. As long you keep the bait cold, they will last a long time...

Downriggin'
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"If you are not scratchin bottom, you ain't fishing deep enough!" -DR

Puget Sound Anglers, Gig Harbor Chapter