Joanna Gambotto Posted October 27, 2012 Report Share Posted October 27, 2012 I've mixed a bucket of glaze lately, been using it for a while and everything was fine, but in the last couple of firings it started to develop bubbles (see photo attached). The bubbles are quite big (around 2mm) with sharp edges. I'm relatively new to pottery and not quite sure what the cause can be... I'll appreciate any piece of advice. Joanna Link to comment Share on other sites More sharing options...
Chris Campbell Posted October 27, 2012 Report Share Posted October 27, 2012 Two things ... Did you have witness cones in the kiln to check what temp it got to? Did you thoroughly mix the glaze to be sure nothing had settled to the bottom? Link to comment Share on other sites More sharing options...
neilestrick Posted October 27, 2012 Report Share Posted October 27, 2012 Is the glaze fairly fluid? What cone? Usually when I run into bubbles like that, it's because the glaze is over-fluxed. Add EPK and flint in equal parts in 2% increments until the problem stops. Link to comment Share on other sites More sharing options...
Joanna Gambotto Posted October 28, 2012 Author Report Share Posted October 28, 2012 will give it a go, thank you. Link to comment Share on other sites More sharing options...
Ben Posted October 30, 2012 Report Share Posted October 30, 2012 Did you have a cone in your bisque firing? It is possible that there is some material converting to gas in the clay body. If this happens after the glaze gets melty then the gas gets trapped under the molten glaze and makes bubbles? Does the glaze have rutile in it? Can you share the clay type, bisque temp, and glaze recipe? Link to comment Share on other sites More sharing options...
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