An hourglass for green tea, an hourglass for black tea, and an hourglass for infusions ... what a great idea! Hint: I was, too, a little blocking problem due to excess moisture content in the sand: simply place the hourglasses from 30 to 40 minutes in an oven set at 40/45 ° C fix the problem (no more hot, might suffer if the hourglasses ...). Product to buy eyes closed for that specific use.