alot of opinions out there for layering! here is the deal 'Specific Gravity
of Alchohol'. here is the web site. just touches on a few liquors and their
specific gravity. if you look around there is a larger list out there.
http://www.hungrymonster.com/bar/Specific_gravity.cfm
i use the mixing spoon when i layer, some use cherry's. the secret is to
rinse and dry the cherry/spoon before every layer. that way the cherry/spoon
is free of residue from the previous layer. it wont contaminate the following
layer.