Thank you very much for your help and comment:)
btw clay I used for those teapots is a mix of two clays from the same german factory:) I am very pleased and have some trust they do not add extra Fe (no glaze inside). I checked how it works (till now) with some greens and white (Bai Mu Dan) with good result for me. Today will try sheng in it.
Sorry, I used to give some links lately but I have some problems with my "internet" and that is not easy for me to uploud pics here (and I have to be in a hurry with descriptions)
so from the left: 130ml, 150ml, 130ml, 150ml