3ds Max :: Wrap Label (just Letters) On Transparent Capsule

I want to wrap a label (just letters) on a transparent capsule which is populated, inside, with instance objects of particles. The label has been photoshopped so that the letters are opaque and the background transparent. Using a Composite Material, with the glass material the Base material, I imported the label and thought it would just show the letters of the label on the capsule. What shows up is the label with a grey background. I can make this transparent by dialing down the opacity, but there must be a better way.