I loved the concept and used the recipe adopted by Difford. However, the blue mix will not float over the yellow layer and rapidly self-mixes. I followed the recipe slavishly (all specified ingredients were used except for the vodka - I used New Amsterdam's Passionfruit vodka for some extra zing) and I used a bar spoon to attempt the float. Tried it a couple of ways and couldn't get the blue layer to stay separated. Disappointing! I may retire to the lab and seek an improvement!!