I think the problem frits are Zimmermann and everyone says its furnace glass and very dense.I seem to have another thread on the same subject and other ideas too
I know I am not reducing but I also know I am using very reactive ones.I will try everyones ideas and I apprrciate all your advice.My Kuglar and Reichenbach behave well so its just the Zimm ones I think..and boy, do I have a lot..lol..Thanks again!