HarryThePotter Posted February 4, 2015 Report Share Posted February 4, 2015 Hi! I understood there are some very experienced ceramic artists here, so I decided to ask this question here. I have a problem. I have a thin porcelain wall and light goes through it easily. I want to totally block this light from going through with the most opaque glazing possible (still has to look good). I have tried different concentrations of tin oxide mixed into normal glazing (from 5% to 30%), but still some light passes through! Do you have any ideas? How would you make the most opaque glazing? Best regards, Harry the Potter Link to comment Share on other sites More sharing options...
Cavy Fire Studios Posted February 4, 2015 Report Share Posted February 4, 2015 Maybe try zircopax (lots cheaper than tin) and throwing/building a wee thicker. Link to comment Share on other sites More sharing options...
Biglou13 Posted February 4, 2015 Report Share Posted February 4, 2015 +one what she said many glazes already have level of opacity built in. what kind of a glaze are you currently using? many aspire for transluscent porcelain...... Link to comment Share on other sites More sharing options...
neilestrick Posted February 4, 2015 Report Share Posted February 4, 2015 Going dark with the glaze would help, too. Try 10% or more iron oxide. Why use porcelain at all if this is an issue? Switch to a stoneware and your problem is solved. You can still go just as thin, but no translucency. Link to comment Share on other sites More sharing options...
HarryThePotter Posted February 4, 2015 Author Report Share Posted February 4, 2015 Thank you for your answers! @TheGuineaPotter How much zirconium would you recommend? @Biglou13 It was some normal glossy glaze. What kind would you recommend? @Neil I use porcelain, because I want to let light through a specific place where I don't have glazing Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted February 4, 2015 Report Share Posted February 4, 2015 Could you add some tin or zicro to the clay? Not sure if that would work. Link to comment Share on other sites More sharing options...
HarryThePotter Posted February 4, 2015 Author Report Share Posted February 4, 2015 @High Bridge Pottery I want to keep the porcelain see-through, but I want the glazing to be opaque. Link to comment Share on other sites More sharing options...
Tyler Miller Posted February 4, 2015 Report Share Posted February 4, 2015 If you've really tried 30% tin, you're not going to get much more opacity than that. 50-50 zircopax and tin will do better than either alone, but I still think it won't be satisfactory. This technique might give you some ideas: http://en.wikipedia.org/wiki/Lithophane Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted February 4, 2015 Report Share Posted February 4, 2015 Ah, yes I didn't read the post above. My bad. 30% of tin seems a lot for any glaze even if it needs to be opaque. I am thinking could you make mix of tin/zicro and maybe a bit of flux to create an opaque wash which you could then glaze over with a transparent. Never seen a glaze that would be 100% opaque. Link to comment Share on other sites More sharing options...
Matt Oz Posted February 5, 2015 Report Share Posted February 5, 2015 Please post a photo. Link to comment Share on other sites More sharing options...
rayaldridge Posted February 5, 2015 Report Share Posted February 5, 2015 You could use a matte glaze. Link to comment Share on other sites More sharing options...
HarryThePotter Posted February 6, 2015 Author Report Share Posted February 6, 2015 If you've really tried 30% tin, you're not going to get much more opacity than that. 50-50 zircopax and tin will do better than either alone, but I still think it won't be satisfactory. This technique might give you some ideas: http://en.wikipedia.org/wiki/Lithophane I should try mixing them both then! Those lithophanes are amazing... Please post a photo. I'm too embarrassed There is so much glazing that it looks like a molten candle. You could use a matte glaze. If I recall correctly, the glazing is matte. But it does not turn out matte. I guess the temperature in the oven goes too high? What do you guys think if glazing was fired in a much lower temperature than what is recommended? Link to comment Share on other sites More sharing options...
HarryThePotter Posted February 6, 2015 Author Report Share Posted February 6, 2015 Ah, yes I didn't read the post above. My bad. 30% of tin seems a lot for any glaze even if it needs to be opaque. I am thinking could you make mix of tin/zicro and maybe a bit of flux to create an opaque wash which you could then glaze over with a transparent. Never seen a glaze that would be 100% opaque. Yeah I should try that mix. What kind of flux? Link to comment Share on other sites More sharing options...
rayaldridge Posted February 6, 2015 Report Share Posted February 6, 2015 Harry, if your matte glaze isn't matte, I would guess that either the glaze is overfired, or it is cooled too quickly for the microcrystals that make the glaze matte to form. Link to comment Share on other sites More sharing options...
HarryThePotter Posted February 7, 2015 Author Report Share Posted February 7, 2015 Harry, if your matte glaze isn't matte, I would guess that either the glaze is overfired, or it is cooled too quickly for the microcrystals that make the glaze matte to form. Thanks for the tip Link to comment Share on other sites More sharing options...
rakukuku Posted February 7, 2015 Report Share Posted February 7, 2015 Could you use slip on the areas you want to be opaque? rakuku Link to comment Share on other sites More sharing options...
PeterH Posted February 7, 2015 Report Share Posted February 7, 2015 Could you use slip on the areas you want to be opaque? rakuku I'd wondered that, but then thought that that line of logic could lead to using shellac-resist/water-erosion. That is it might be neater to remove some of the pot rather than add something to it. [Adding a clear glaze if you want it glossy.] Which does raise the question: why is slip/porcelain more opaque than a white glaze? Is it just thickness, or what? Is the light absorbed or just scattered? PS Tim Gee's work https://www.flickr.com/photos/hypercontextualism/2071710213/ https://www.pinterest.com/ebakla/ceramic-tim-gee/ Link to comment Share on other sites More sharing options...
HarryThePotter Posted February 9, 2015 Author Report Share Posted February 9, 2015 Could you use slip on the areas you want to be opaque? rakuku I'd wondered that, but then thought that that line of logic could lead to using shellac-resist/water-erosion. That is it might be neater to remove some of the pot rather than add something to it. [Adding a clear glaze if you want it glossy.] Which does raise the question: why is slip/porcelain more opaque than a white glaze? Is it just thickness, or what? Is the light absorbed or just scattered? PS Tim Gee's work https://www.flickr.com/photos/hypercontextualism/2071710213/ https://www.pinterest.com/ebakla/ceramic-tim-gee/ Some of the glazing is removed later on. Removing slip might be hard... Tim Gee's works are beautiful... Link to comment Share on other sites More sharing options...
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