smesa Posted April 23, 2021 Report Share Posted April 23, 2021 I bought a dry bag of speckled white glaze and added water to arrive to a milky consistency. I mix well before glazing. None of my firings have gone well. Clay body is speckled stoneware. It crawls on some parts because too thick and looks washed on other parts (on same piece)! I have tried pouring, dipping, brushing. Dipping seems to work best-but not particularly well either. Not sure what i’m doing wrong. Here are some photos for reference (all different firings, cone 5.5/6 glaze label says cone 5-9). Also, the inside is usually what comes out with best results.. my kiln runs with a kiln sitter and a cone 6 firing lasts about 6.5 hours on average. The kiln has an automatic thumb wheel to rise in temp. Is the kiln running too fast? The witness cones are right on target with a cone 5.5 temp. Link to comment Share on other sites More sharing options...
thiamant Posted April 23, 2021 Report Share Posted April 23, 2021 I'm not an expert but.. Have you tried waiting at least 24/48 hours after glazing the piece before firing it? Link to comment Share on other sites More sharing options...
smesa Posted April 23, 2021 Author Report Share Posted April 23, 2021 55 minutes ago, thiamant said: I'm not an expert but.. Have you tried waiting at least 24/48 hours after glazing the piece before firing it? Never, I always pop them in when they look dry / can be touched without damaging the glaze . Could damp glaze have an effect? Link to comment Share on other sites More sharing options...
GEP Posted April 23, 2021 Report Share Posted April 23, 2021 When you mixed up the glaze, did you put it through a sieve? And if so, how many times? Some of my glazes look fine after two passes through a sieve, but some definitely need three or four before all the globs are worked out. The area of crawling in the third photo indicates there are still some thick globs in your batch. And this would explain the thinner areas too. Link to comment Share on other sites More sharing options...
neilestrick Posted April 23, 2021 Report Share Posted April 23, 2021 Looks to me like maybe your glaze is too thin, so it's not applying evenly. You could measure the specific gravity, but if you don't want to get that technical just shoot for a thick chocolate milk consistency, which gives a good application with a 5-6 second dip. Link to comment Share on other sites More sharing options...
smesa Posted April 23, 2021 Author Report Share Posted April 23, 2021 1 hour ago, GEP said: When you mixed up the glaze, did you put it through a sieve? And if so, how many times? Some of my glazes look fine after two passes through a sieve, but some definitely need three or four before all the globs are worked out. The area of crawling in the third photo indicates there are still some thick globs in your batch. And this would explain the thinner areas too. I’ve never used a sieve, gonna give that a try Thank you Link to comment Share on other sites More sharing options...
Hulk Posted April 23, 2021 Report Share Posted April 23, 2021 Nice pots! The crawly bit near the bottom of the third pot, could that be from an oily fingerprint, or waxy fingerprint? The banding on the exterior (thinner and thicker), just curious, are you glazing the interior, then waiting on the piece to fully dry before glazing the exterior? It might take a day or so for the moisture to evaporate. If the banding follows variations in wall thickness, that could be a factor. You're mixing the glaze, however, if the glaze settles quickly, it can get more watery at the surface in just a minute or so; try giving the glaze a good spin with your whisk right before. For dipping, an evenly paced, smooth plunge, then a similarly even withdraw seems to make a difference as well; I'm pausing and/or speeding up on the withdraw when I want banding. Looks like there's some dripping on that third piece. Did you dip that one foot first? Any road, I'm really appreciating Tony Hansen's take on adjusting specific gravity down a bit, then gelling the glaze such that it is liquid when moving, and gels when it stops moving (see article and video Thixotropy and How to Gel a Ceramic Glaze (digitalfire.com)). Trying for repeatability, so, I'm taking notes on specific gravity, how the glaze goes on, film thickness, and fired results; sometimes the notes help! As for adjusting thixotropy, once thoroughly stirred and sieved, specific gravity checked/adjusted, I'm stirring clockwise (easier on my wrist) at an easily repeatable speed until the entire mass is revolving, then observing the behaviour after removing the whisk; the revolving mass spins and slows together, comes to a stop after about three turns, then bounces back a bit as the glaze all gels. Contrast the behaviour before adjusting thixotropy, where the glaze just keeps on spinning, where there are currents at different speeds - the different speeds shearing against each other - and when the mass eventually stops, no bounce back. The keeps on spinning glaze drips and runs on the ware, ugh. On the other hand, after the treatment, might take longer for the glaze to dry, a bit longer dip/pour time may be required to get your thickness... All that to say - adjusting specific gravity and thixotropy is really helping me in gettin' glazes to behave! I'm shooting for between 1.39 to 1.47 sg (depending on the glaze - per them notes), and about three turns before stopping all together on the mix test, at speed matching Positive Vibration. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted April 23, 2021 Report Share Posted April 23, 2021 1 hour ago, smesa said: I’ve never used a sieve, gonna give that a try Thank you This is probably the issue. If your glaze materials aren’t evenly dispersed, it could account for the weird thick/thin issues, and concentrations of some ingredients in one spot causing crawling. Sieve your glaze, and if that doesn’t work, then move on to the specific gravity/thixotropy troubleshooting suggestions here. You want to use an 80 mesh sieve, and run it through at least twice. You will have to re-sieve the bucket if you add more dry ingredients to your batch, or if it sits for a while and you have dry bits dropping into the slurry from the sides of the bucket. Link to comment Share on other sites More sharing options...
thiamant Posted April 23, 2021 Report Share Posted April 23, 2021 Indeed, sieving glazes is really important. I even sieve my test glazes a couple of times when I do test tiles. Link to comment Share on other sites More sharing options...
smesa Posted April 23, 2021 Author Report Share Posted April 23, 2021 3 hours ago, Hulk said: Nice pots! The crawly bit near the bottom of the third pot, could that be from an oily fingerprint, or waxy fingerprint? The banding on the exterior (thinner and thicker), just curious, are you glazing the interior, then waiting on the piece to fully dry before glazing the exterior? It might take a day or so for the moisture to evaporate. If the banding follows variations in wall thickness, that could be a factor. You're mixing the glaze, however, if the glaze settles quickly, it can get more watery at the surface in just a minute or so; try giving the glaze a good spin with your whisk right before. For dipping, an evenly paced, smooth plunge, then a similarly even withdraw seems to make a difference as well; I'm pausing and/or speeding up on the withdraw when I want banding. Looks like there's some dripping on that third piece. Did you dip that one foot first? Any road, I'm really appreciating Tony Hansen's take on adjusting specific gravity down a bit, then gelling the glaze such that it is liquid when moving, and gels when it stops moving (see article and video Thixotropy and How to Gel a Ceramic Glaze (digitalfire.com)). Trying for repeatability, so, I'm taking noting specific gravity, how the glaze goes on, film thickness, and fired results; sometimes the notes help! As for adjusting thixotropy, once thoroughly stirred and sieved, specific gravity checked/adjusted, I'm stirring clockwise (easier on my wrist) at an easily repeatable speed until the entire mass is revolving, then observing the behaviour after removing the whisk; the revolving mass spins and slows together, comes to a stop after about three turns, then bounces back a bit as the glaze all gels. Contrast the behaviour before adjusting thixotropy, where the glaze just keeps on spinning, where there are currents at different speeds - the different speeds shearing against each other - and when the mass eventually stops, no bounce back. The keeps on spinning glaze drips and runs on the ware, ugh. On the other hand, after the treatment, might take longer for the glaze to dry, a bit longer dip/pour time may be required to get your thickness... All that to say - adjusting specific gravity and thixotropy is really helping me in gettin' glazes to behave! I'm shooting for between 1.39 to 1.47 sg (depending on the glaze - per them notes), and about three turns before stopping all together on the mix test, at speed matching Positive Vibration. Thanks for the advice, i’ll let the pieces dry longer and see if that helps with the exterior since I glaze the interior first. Then i’ll move on to other theories if that doesn’t do the trick Link to comment Share on other sites More sharing options...
liambesaw Posted April 23, 2021 Report Share Posted April 23, 2021 The crawling looks like dust/oil crawl Link to comment Share on other sites More sharing options...
Hulk Posted April 24, 2021 Report Share Posted April 24, 2021 Banding on purpose! Picked this from latest glaze load, where outside dipped upside down, varying the speed of the lift out of the glaze bucket - slow down, pause, accelerate - created a horizon effect that I was looking for. Per prior, I'm glazing the outside the next day after liner glazing - else putting the liner glazed pieces outside in the sun and breeze for a quicker turnaround... Where trying for a more even application, at and just below the rim typically ends up a bit thicker, being at the bottom, however, the tool line/lines - I'm burnishing that bit at the top - mitigate. Link to comment Share on other sites More sharing options...
Bill Kielb Posted April 25, 2021 Report Share Posted April 25, 2021 11 hours ago, Hulk said: Where trying for a more even application, at and just below the rim typically ends up a bit thicker, being at the bottom, however, the tool line/lines - I'm burnishing that bit at the top - mitigate. Hey, master the ombré dip! Fantastic! Link to comment Share on other sites More sharing options...
Babs Posted April 26, 2021 Report Share Posted April 26, 2021 I love the effect of your glaze on the speckled clay. On top of glaze inside one day and exterior the next, though on pots of your thickness may be not as important as stirring your glaze after each pot dipped. Some glazes need this unless flocculated. If want a whiter glaze add some zircopax Link to comment Share on other sites More sharing options...
smesa Posted April 26, 2021 Author Report Share Posted April 26, 2021 17 hours ago, Babs said: I love the effect of your glaze on the speckled clay. On top of glaze inside one day and exterior the next, though on pots of your thickness may be not as important as stirring your glaze after each pot dipped. Some glazes need this unless flocculated. If want a whiter glaze add some zircopax Thank you Babs, all these tips are very appreciated. I’m a beginner ceramicist and making alot of mistakes along the way haha Link to comment Share on other sites More sharing options...
Babs Posted April 27, 2021 Report Share Posted April 27, 2021 10 hours ago, smesa said: Thank you Babs, all these tips are very appreciated. I’m a beginner ceramicist and making alot of mistakes along the way haha Start making notes now! Don't think anyone knows everything about this field ever. Extremely generous and knowledgable folk in these forums. won't ever be bored again! Link to comment Share on other sites More sharing options...
smesa Posted April 29, 2021 Author Report Share Posted April 29, 2021 So I re-glazed these pieces and tried new test pieces with all of your advice! Thank you all for the great tips, the glaze came out MUCH better this time around. I ended up seiving the glaze x2 and waiting 48 hours for it to dry before firing. Will keep trying to see what works best... it seems with the test pieces the right one was nicer and I remember pouring on a bit longer on that one. Link to comment Share on other sites More sharing options...
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