JonS
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Post by JonS on Feb 24, 2020 16:02:12 GMT -8
I made a small dome to see if the shape would hold up. photos.app.goo.gl/5Jstc4zpQkQXm2JV8The fire wasn't great (took a little while to get going) but the stove did eventually heat up. The first temp (845C) is in the heat riser and the second (476 C) is right below the mini dome.the geopolymer had no cracks! photos.app.goo.gl/RhBrfT1VyH3oPP169With this success, I ordered enough kaolin for the full dome. |
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JonS
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Post by JonS on Feb 24, 2020 16:27:21 GMT -8
Karl, is calcined clay essential in this mix? I purchased #6 tile because it was the most cost effective option... If I am carful not to heat it too quickly through the clay water loss event (450C-around 550C) would I be okay?
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Deleted
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Post by Deleted on Feb 25, 2020 9:40:16 GMT -8
No calcined clays required.
The formula was developed for natural clays.
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JonS
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Post by JonS on Mar 23, 2020 15:55:09 GMT -8
I finally got my materials after the clay was back ordered (had to switch to Helmer clay). This project was bigger than I anticipated. I ended up making 4 batches to total a cubic foot. One of the time consuming parts was shredding enough rockwool. I eventually added a wire to a cement mixer that you would use with a drill and it went faster. photos.app.goo.gl/MndgKsZsXdQxbd8T6 I am sure a weed whacker would have been faster but I didn't have one. This is what the dome looks like right now. photos.app.goo.gl/PiAY5gEHTt2LKUAo9 I am pretty happy with it and am hoping it doesn't crack while drying 🤞. I will let you know how it turns out. |
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JonS
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Post by JonS on Mar 28, 2020 11:05:42 GMT -8
So the dome cracked... photos.app.goo.gl/hhJd2b4g66Wmjcex5 I think that I will still be able to salvage it by mortaring the broke parts back on once it is dry. I also thought I was making it thicker when I was troweling material on but was way too thin. If I did this again, I would have cast the end shap and then cast a bunch of board shaped pieces (perhaps 2x4x27) and mortaring them together once everything was dry. |
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Post by sksshel on Mar 29, 2020 4:38:18 GMT -8
You are making good progress. I think your idea about the "board shaped pieces" is a good one.
Your dome appears to be brown. All of my components ended up a very light grey. Do you know what caused the color difference?
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JonS
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Post by JonS on Mar 29, 2020 7:31:39 GMT -8
Sksshel, thanks for the encouragement! I was also wondering about the strange color. The kaolin I ended up using (Helmer) isn't quite as white as the small samples I was using but even those started out a little brown before bleaching out. I figured it was part of the chemical reaction or something... I think it will lighten up when it dries. You can sort of see the dry color where it pulled away from the mold in this picture (I wish I could figure out how to show the picture instead the link through my phone since I can't right click...). photos.app.goo.gl/wFcZN6dt8avzo6FG6 |
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Deleted
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Post by Deleted on Mar 30, 2020 6:21:08 GMT -8
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JonS
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Post by JonS on Apr 4, 2020 16:10:18 GMT -8
Thanks Karl, apparently they add seems of red iron to this clay to enhance "flashing." Will the iron cause any issues? I don't think the stove will be getting hot enough but wasn't sure. I hit 1160C at the bottom of the riser in a test fire without the dome on earlier in the week... plainsmanclays.com/data/index.php?product=12909I got the dome out of the mold and re-attached the front. I extended the chimney down a little bit to make it more of a bell but I would prefer it to be an inch or so lower when it is done. I also filled in a bunch of the divots on the underside of the dry mold. photos.app.goo.gl/G3ntSMEYawufkhAp8 |
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Post by firewatcher on Jun 18, 2020 6:48:42 GMT -8
Karl, is calcined clay essential in this mix? I purchased #6 tile because it was the most cost effective option... If I am carful not to heat it too quickly through the clay water loss event (450C-around 550C) would I be okay? I see a couple of replies down in this thread that you are no longer using the 6-tile clay...just a quick comment from my side based on experience and feedback from [mention]karl [/mention]. 6-tile didn’t work (for me) as it shrank too much and required too much water to make a usably viscous mix. Just my 2 cents based on my limited experience. |
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Post by tardigrade on Nov 11, 2020 8:41:58 GMT -8
Does anyone know if substituting NaOH for the KOH in this recipe would work or if it "ruins the chemistry"?
NaOH will work as well. The molar mass of KOH is 1.4 times higher therefore the number given vor KHO can be divided by 1.4 for using NaOH instead.
The original recipe uses soda ash.
I had created it due to complaints about the extremely dangerous chemicals usually used for geopolymers.
If switching to soda ash instead (NaOH) rather than KOH; would the Monopotassium phosphate (MKP - KH₂PO₄) still be needed? If the MKP was still needed, could it in turn be replaced by Trisodium phosphate (Na₃PO₄)? If so, any shift in measurement/weight? Asking as soda ash and TSP happen to be more readily available at a lower cost based on my location. |
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Deleted
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Post by Deleted on Nov 12, 2020 0:46:28 GMT -8
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grga
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Post by grga on Dec 8, 2020 11:22:40 GMT -8
I like your work and posts as well as several others working on geopolymers. However I have 2 comments/questions. 1) I am wondering how cheep and good this really is? - I got the info somewhere on this forum that cca. 40 euro for one batchbox...? For comparison for my projects I bought a bag of Calcium Aluminate Cement (https://calucem.com/products/istra-types/istra-40/) a bag of 20 kg for 25 eur. Than mixing it with grog (made from crunched from fireclay bricks leftovers, nearly free but some work required). One part cement, 3 part grog, dry mix and add a small amount of water - that is very simple and fast. From that I could make cca. 3 batchboxes or more - so for cca. 25 eur. Or under 10 eur for one BB rocket (18cm riser). And it holds together for the 3rd season (more than 400 fires) without any problems. 2) although the donkey32.proboards.com/thread/2372/simple-straight-away-ltgs-binder as well as donkey32.proboards.com/thread/3283/geopolymer-code-named-kansas-cityare well documented there is still is not enough clear to me how to follow it where to get the right ingredients etc. since I have no experiences in geopolymers but I do not like loosing too much time failing and repeating the experiments. So this might be the reason (price, complication and simplicity) why there is not many projects of batchbox rockets done with geopolymer? I would be happy to hear that I am wrong and even more if you or anyone would also explain it to me. I love to do thinks good and cheap... |
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Post by Vortex on Dec 8, 2020 12:11:49 GMT -8
The homemade castable mix you describe in number 1, is how it's made commercially. I figured it out about 5 years ago, after a sack I bought had some large pieces of grog in it that had somehow escaped the crusher. They were a mix of bits of old porcelain electrical insulators and old red clay bricks.
We made some casts after using a mix of crushed up old French glazed roof tiles screened upto 3mm and calcium aluminate cement 4/1. They have been in use for 4+ years and going strong.
The main difference I see in your above question is the grog/CA cement mix is a dense refractory and Karl's are insulators, which do you need?
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Deleted
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Post by Deleted on Dec 9, 2020 7:39:09 GMT -8
So this might be the reason (price, complication and simplicity) why there is not many projects of batchbox rockets done with geopolymer? I would be happy to hear that I am wrong and even more if you or anyone would also explain it to me. I love to do thinks good and cheap...
With respect to simplicity: Very fine powder of basalt stone can be hardened with citric acid or even with vinegar, but also with lye or salts like trisodium phosphate, quicklime will work pretty well too also hydrated lime.
Powders of primary stones except those with high quartz content like granite can be used to replace grog.
Prices depend largely on the location. Where in the EU are you located?
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