Nini

Hi Babs, thank you for your advice. Yes I’m starting to think that sealing the interior after firing might be the best solution… I wanted to avoid this and keep it purely in the ceramic realm but I suppose as a back up option for the ones that still leak after glazing it wouldn’t be the worst pottery sin!!  I don’t make any tableware from this, it would be only vases or plant pots. 
I think safe to say I’m not using talc in the traditional (or maybe even sensible) way! It was some years ago that I started playing around with low fire talc bodies, and then I tried firing it to cone 6 and found that some glazes looked really interesting on it, so I kept exploring. What I’ve been making from this body is not thin at all, in fact the opposite - because it’s so light and marshmallow-y I can get super thick sections without the piece cracking or weighing a tonne, and I enjoy the look of that. I basically make big rocks… would just love to make a hollow one I can put a plant in  
COE is not something I’ve fully wrapped my brain around yet but yes that is definitely the culprit for a lot of glazes not fitting. I have found glazes that fit but the issue is if there’s any tiny section where the glaze doesn’t cover the inside, or pinholes, the whole thing is bust because the clay is nowhere near vitrified. From what I understand talc in high quantities at this temp is very refractory, so keeping it in that % i don’t imagine I could get it to mature, but this is something I’m still quite new to so I may be wrong. Just not sure what I might try to attempt to get it to vitrify