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Hello, I am a new member (and new to pottery in general) and have struggled to find the answer to the glaze defects I have been experiencing on previous posts in this forum. I am having trouble with pinholing/pitting/airbubbles (not sure exactly what to refer to it as). Most of my glazed pottery either has loads of little holes (this is especially bad with black underglaze topped with clear) or lots of tiny bubbles trapped beneath the surface. To provide a background, the clay I have been using is Scarva Earthstone ES5 Original White Stoneware Clay, which has a firing temperature of 1200-1290°C and some grog in. I have primarily been using Amaco velvet underglaze, which I apply on cone 04 bisqueware and top with Amaco clear gloss (HF-10), before firing to cone 6 on slow. I only use the standard programmes on my little Skutt Firebox as I have not figured out setting up my own yet (i.e. with soaks). Using tips from previous posts, I have tried wet-sanding bisque fired pieces before glazing, and making sure they are washed and dust free. I have also experimented with slow firing vs medium. The sanding helped a lot and I have fewer pinholes now, but am still getting loads of tiny little pits on (specifically) the black underglaze. I am not sure why this is different to the other colours or clear gloss over bare stoneware (but this still has lots of airbubbles underneath, they just aren't breaking the surface). I have attached some close-up photos of the issues, which hopefully are good enough quality to be visible. I am not sure what is causing this and would be really grateful if anyone has any ideas? Thanks, Ellie
Hi there. I recently glazed some items on white stoneware clay. The clay (White Stoneware PF560) was glazed fired after being bisqued at : room --> 600 degrees C at 100 deg/c per hour 600 -> 1230 at 150 deg/c per hour 20 min soak It came out really patchy and there are some air bubbles. If anyone could recommend good firing ramp for this glaze in degrees celcis with timing that would be great - thanks so much Terracolor orange Ember - https://www.scarva.com/en/gb/Terracolor-FS6031-Orange-Ember/m-1772.aspx was the glaze that didnt look very good! Clay was : https://www.bathpotters.co.uk/white-stoneware-pf560