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Post by Deleted on Jun 2, 2014 5:03:53 GMT -8
If I use no lye at all, what happens then? The clay will lower the PH value. If it becomes to low, parts of the metasilicate will then polymerize to the colloidal form, thus increasing viscosity. With respect to the medicine: DIY or DIE One can learn a lot if there is only this choice.
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Post by DCish on Jun 2, 2014 6:25:28 GMT -8
DIY or DIE... quite the motivator!
So the idea is to add some lye to the waterglass to boost the PH, then mix in the clay, yes? Could I trouble you for a ratio of waterglass : lye : clay?
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Post by Deleted on Jun 2, 2014 7:02:09 GMT -8
So the idea is to add some lye to the waterglass to boost the PH, then mix in the clay, yes? Yes. Depends on the kind of clay and other factors, I am afraid you will have to make some experiments. The general rule: the more waterglass the more green strengs. But if it is to much to completely react chemicaly with the clay when fired, the remaining waterglass may cause efflorescences in an humid environment. The amount of lye depends on the clay too, for two reasons, varying PH and varying amounts of liquid required. About 2% should suffice.
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Post by DCish on Jun 2, 2014 9:06:04 GMT -8
2%... of what amount? Of the amount of clay? So the first calculation gives ratios of:
2.7Kg Metakaolin : 1Kg waterglass : 92g Lye
Or I could do "waterglass only" and reduce the lye in the mix to 54g (2% of 2.7Kg) for greater "green strength".
So now I'm wondering how much green strength matters, since it'll be a rocket batch box core that'll be baked when in use anyway. Will the "baked strength" be much different between the two mixes?
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Post by Robert on Jun 2, 2014 13:44:12 GMT -8
i am following your project please Dcish lot of pictures and simple english for kindergarten kids like me:)i tried before the ceramic blanket soaked in waterglass for the riser... i am not so happy abou the results... Karl i hope that your medicine will help you.
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Post by DCish on Jun 2, 2014 14:54:17 GMT -8
Inching along, inching along... . Will certainly post as things develop.
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Post by Deleted on Jun 3, 2014 2:51:56 GMT -8
2% of the waterglass solution. The waterglass increases "baked strength" too.
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Post by Deleted on Jun 3, 2014 3:41:16 GMT -8
i tried before the ceramic blanket soaked in waterglass for the riser... i am not so happy abou the results... Waterglass needs o be mixes with clays rich in alumina or magnesia, so that it can form high temperature minerals at firing. Resistance to higher temperatures can be achieved by adding clay to the formulation. Depending on the aluminum or magnesium content of the clay, service temperatures up to 3200 to 3400 o F are possible due to the formation of a ceramic bond. Obviously it does. I am still alive, after a long time. I am not aware of someone else.
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Post by DCish on Jun 3, 2014 12:45:52 GMT -8
Oops! So it's: 2.7Kg metakaolin : 1Kg waterglass : 20g lye, right?
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Post by Deleted on Jun 4, 2014 3:08:46 GMT -8
So it's: 2.7Kg metakaolin : 1Kg waterglass : 20g lye, right? Yes. Be careful, even this small amount of NaOH will increase the PH of the waterglass solution to 14.
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Post by DCish on Jun 4, 2014 3:36:38 GMT -8
Sweet, on to the next step, finding materials and playing around. Thanks for your patience in walking me through this. Will take precautions with the NaOH.
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Post by DCish on Jun 16, 2014 13:41:54 GMT -8
So I've been looking at materials as time has allowed, and the best buy I could find on waterglass was $35 per gallon... before shipping. After poking around a bit I also found furnace cement locally for $30 per gallon. From the MSDS below, it looks like I could basically take a kilogram of furnace cement, add a kilogram of fire clay, and be good to go. Or more simply, go with straight furnace cement to bond my ceramic paper. Any thoughts? Getting closer to Matthew Walker's recipe...
Furnace cement ingredients, % by weight: Sodium silicate 30-60% Kaolinite, Hydrous Aluminum Silicate 10-30% Wollastonite (Ca(SiO3)) 5-10% Mica 1-5% Nepheline Syenite 10-30% Microspheres 0-3 %
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