birdypotter Posted September 12, 2015 Report Share Posted September 12, 2015 Very irritating problem - stoneware transparent glaze on a white stoneware body, comes out more satin than it does glossy and when looking close the surface has thousands of tiny bubbles suspended in the glaze. As well as satiny finish it gives an every so slightly uneven surface when in relief. Especially noticeable over colour. I bisque fire to 1000 and then glazing to 1270. My glaze is particularly thin, more milk than cream, as I both dip and spray and was told to think glaze because of bubble problem. Is this a really common problem with a simple solution that I'm missing? I've recently ordered a sample of new glaze recommended by the same company that make the brand of clay I use and so maybe it will be a better fit all round, but I have a fair bit of my current glaze left and want to be able to try and solve the problem and use that before switching glazes. After trying lots of variations of firing schedules and temperatures and glaze thicknesses I'm really lost! It might just be one small thing I need to change but it's a nightmare trying to figure out what it is when there's so much that can affect a glaze! I've found lots of info on blistering but nothing on tiny bubbles. Help! Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted September 12, 2015 Report Share Posted September 12, 2015 Do you have the glaze recipe? First option would be swapping out any material that releases gas. http://digitalfire.com/4sight/glossary/glossary_glaze_bubbles.html Link to comment Share on other sites More sharing options...
bciskepottery Posted September 13, 2015 Report Share Posted September 13, 2015 If the glaze is supposed to come out glossy/shiny, but is firing to satin then you might not be reaching final temperature. Consider adding a soak to the end of your glaze firing period -- that will allow the glaze to reach full temperature and also allow the glaze to even its melt before starting to cool. Is there a lot of frit in the glaze recipe? That could also be an issue. Link to comment Share on other sites More sharing options...
Mark C. Posted September 13, 2015 Report Share Posted September 13, 2015 More heat Scotty. Mark Link to comment Share on other sites More sharing options...
Joseph Fireborn Posted September 13, 2015 Report Share Posted September 13, 2015 You can also try to fire slower to the top temp and soak to get your heatwork. This will depend on when your glaze starts melting. I would also add in a slower cool instead of just shutting off your kiln slow cool for an hour or so to give bubbles time to get out of the matrix. Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted September 13, 2015 Report Share Posted September 13, 2015 I thought you took the red pill to get out the matrix Link to comment Share on other sites More sharing options...
Joseph Fireborn Posted September 13, 2015 Report Share Posted September 13, 2015 I thought you took the red pill to get out the matrix Not the bubble matrix. Some materials are just gassy though, you need to get the glaze fire either hotter, as Mark said, give it more time to heat slowly as to let the bubbles escape as Bruce said, or slow cool and hold on the way down. You will have to test to see which one works... Some people like the bubbles in the matrix. I have a beautiful cup I bought that has a blue celadon with lots of little bubbles in a bubble matrix. Link to comment Share on other sites More sharing options...
Matt Oz Posted September 13, 2015 Report Share Posted September 13, 2015 Tiny bubbles In the glaze Make me happy Make me feel fine Sorry, I'm old Link to comment Share on other sites More sharing options...
oldlady Posted September 13, 2015 Report Share Posted September 13, 2015 never be sorry you are old. think of the alternative and just be happy. Link to comment Share on other sites More sharing options...
birdypotter Posted September 13, 2015 Author Report Share Posted September 13, 2015 Absolutely loving these replies, making me laugh instead of cry at my crappy bubbly glaze! I'm using a locally bought commercial glaze so maybe mixing my own needs to be an option. My glazing schedule is 90 up to 700 and then full to 1270 with a 25 min soak. I don't shut off the kiln till it's cooled riiiiiight down at around 60- takes an absolute age - what sort of slow down would you suggest I programmed into the cooling period? the max temp on both glaze and clay is 1280 - should I take it right up to this?? also, the bubbles don't look terrible, but you can see it has a very slight orange peely texture in the right light. And I guess when you're trying to achieve a certain finish it kind of doesn't matter if it turns out alright another way - you kind of just want to get it how you meant to in the first place you know? Link to comment Share on other sites More sharing options...
martinkohout Posted September 25, 2015 Report Share Posted September 25, 2015 Could anyone please give more specific details about the experience of lengthening the firing or increasing the soak specifically? I have a similar problem, with big bubbles in my glaze and I would like to try to test giving it more heat, but don't know how big the steps shall be. I follow this programme, yet skipping the first step and the last one, since our kiln can be only programmed in three ramps. Since the main soak is only 15 minutes, shall I add 10 minutes on top or is that already gonna be a big difference and it's better to test with less time being added? Thanks for any help! http://digitalfire.com/4sight/firingschedule/plainsman_cone_6_electric_standard_firing_schedule_114.html 3 60°C/hr to 1190 108 2175 15min Link to comment Share on other sites More sharing options...
neilestrick Posted September 25, 2015 Report Share Posted September 25, 2015 Could anyone please give more specific details about the experience of lengthening the firing or increasing the soak specifically? I have a similar problem, with big bubbles in my glaze and I would like to try to test giving it more heat, but don't know how big the steps shall be. I follow this programme, yet skipping the first step and the last one, since our kiln can be only programmed in three ramps. Since the main soak is only 15 minutes, shall I add 10 minutes on top or is that already gonna be a big difference and it's better to test with less time being added? Thanks for any help! http://digitalfire.com/4sight/firingschedule/plainsman_cone_6_electric_standard_firing_schedule_114.html3 60°C/hr to 1190 108 2175 15min Your glaze problem is different than this one. Check your other post. Link to comment Share on other sites More sharing options...
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