After a few experiments, I have got this right! These specially made glasses can generate extra foamy beer and keep the foam for longer time so that you can enjoy rich creamy beer. I am so happy with the effect I have made 100 glasses last year to sell at Christmas bazaar and also I have give away some to my friends. Now, there are only a few pairs left in which I am selling at DIS shop and Hein Art Gallery. I am very happy during the process as I can test coloring on 100 glasses and most of them come out great and unique. Maybe when I have time, I would do this project again!