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birdypotter

Tiny Bubbles Suspended In Clear Glaze

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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!

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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. 

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I thought you took the red pill to get out the matrix  ;)

 

Not the bubble matrix.  :ph34r:

 

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.

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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? 

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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

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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

 

 

Your glaze problem is different than this one. Check your other post.

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