If your base mixture (milk and coffee) isn’t chilled or cold, then there is a tendency for your drink to separate, leaving a watery frappuccino. Another reason can also be that you messed up the milk-to-syrup ratio. Don’t go overboard with the sweetness by putting in more milk or vanilla syrup. If you really want a thicker consistency, then we suggest adding in a bit of vanilla smoothie powder or vanilla soft-serve ice cream mix. It also adds sweetness to the frappe base. Add about 2 to 4 tablespoons per drink served.