i have to say I am totally stumped when it comes to consistent head. Out of the same brews the results can vary from great (creamy, lace down the glass etc), average, and then to nothing.Bubbles dont seem to be a problem, but head often is. I've noticed that i seem to get better results out of reused twist tops than my Pet bottles or even my flip top bottles, but even then its not always the same between bottles of the same type. Maybe it is the glass,. or ambient temerpature or how long its been in the fridge?? At the moment it seems like pot luck as to whether I will be drinking a heavenly brew or something a bit disappointing.