I was actually browsing around for more information on foamed glass for a high temperature displacer but came across this interesting method for molding glass powder into specific shapes then fusing it.
I have had some ideas for making glass Stirling engines.
The subject of making glass or ceramic engines is considerably different from turning parts on a metal lathe or metal casting so I thought this video could be the start of a new thread on the topic and additional information can be added as I, or anyone else comes across it, or has their own glass engine project to share.
https://youtu.be/FKAuIkFFKPY
Making Glass and Ceramic Stirling engines
Re: Making Glass and Ceramic Stirling engines
There are a lot of additional videos on "freeze and fuse".
This video is quite long, so I'm skipping to the end. It is part of a long series. This last video in the series shows some of the potential and level of detail possible with this freeze and fuse method of glass working. From other similar videos I've seen, I think this fish tank landscape scene may have been overheated or left in the kiln a bit too long as some of the details seems to have been lost in the final fusing.
https://youtu.be/5kJp-oURVes?t=1500
Though not having ever done any glass fusing whatsoever, beyond having some broken glass partly melt in a camp fire, I've already come up with a theoretical methodology that might alleviate some of the problems inherent in this method.
The crushed glass "sand" or frit tends to retain tiny air pockets that make the finished item look cloudy or muddy. This can be reminded by additional heating at a higher temperature, but at the sacrifice of some detail and shrinkage.
So, I was considering, what if the crushed glass were soaked with a strong water glass (sodium silicate) solution instead of plain water? Might that not fill in the gaps between the crushed glass particles?
On heating and drying the water glass would revert back into glass, producing a piece with greater clarity and retaining the fine detail.
This video is quite long, so I'm skipping to the end. It is part of a long series. This last video in the series shows some of the potential and level of detail possible with this freeze and fuse method of glass working. From other similar videos I've seen, I think this fish tank landscape scene may have been overheated or left in the kiln a bit too long as some of the details seems to have been lost in the final fusing.
https://youtu.be/5kJp-oURVes?t=1500
Though not having ever done any glass fusing whatsoever, beyond having some broken glass partly melt in a camp fire, I've already come up with a theoretical methodology that might alleviate some of the problems inherent in this method.
The crushed glass "sand" or frit tends to retain tiny air pockets that make the finished item look cloudy or muddy. This can be reminded by additional heating at a higher temperature, but at the sacrifice of some detail and shrinkage.
So, I was considering, what if the crushed glass were soaked with a strong water glass (sodium silicate) solution instead of plain water? Might that not fill in the gaps between the crushed glass particles?
On heating and drying the water glass would revert back into glass, producing a piece with greater clarity and retaining the fine detail.
Last edited by Tom Booth on Sat Mar 25, 2023 8:37 am, edited 3 times in total.
Re: Making Glass and Ceramic Stirling engines
So they are basically sintering glass as you would with metal powder it seems?
Re: Making Glass and Ceramic Stirling engines
I'd say so.
Have to be careful not to heat the glass "sand" too high or for too long or it would lose its shape and melt into a puddle.
I've made some progress with this, but in my experience so far, a microwave kiln is very difficult to regulate and get even heating.
It would probably be preferable to use a "real" programmable kiln for any serious glasswork.
Re: Making Glass and Ceramic Stirling engines
One could always get a bunch of aluminum oxide sand blast media and stick it together with a small amount of sodium silicate (water glass). Tim Tinker has done this. Aluminum oxide melts at a much higher temperature than quartz glass. It is also known as sapphire or porcelain. Sapphire is one of the strongest yet brittle natural materials known to man, second to diamond. Aluminum is one of the most abundant elements.
Of course magnesium oxide has an even higher melting point as does zircon. How ever those last two are less common elements and most likely more, to way more, expensive. All three are used for firebrick.
https://timtinker.com/diy-refractory/
Of course magnesium oxide has an even higher melting point as does zircon. How ever those last two are less common elements and most likely more, to way more, expensive. All three are used for firebrick.
https://timtinker.com/diy-refractory/
Re: Making Glass and Ceramic Stirling engines
Thanks for the info, I might try some of that.Fool wrote: ↑Fri Aug 11, 2023 6:38 am One could always get a bunch of aluminum oxide sand blast media and stick it together with a small amount of sodium silicate (water glass). Tim Tinker has done this. Aluminum oxide melts at a much higher temperature than quartz glass. It is also known as sapphire or porcelain. Sapphire is one of the strongest yet brittle natural materials known to man, second to diamond. Aluminum is one of the most abundant elements.
Of course magnesium oxide has an even higher melting point as does zircon. How ever those last two are less common elements and most likely more, to way more, expensive. All three are used for firebrick.
https://timtinker.com/diy-refractory/
I've found buying clay is very expensive, especially mail order as it's also heavy so shipping charges are ridiculous.
So...
I found this video extremely interesting.
https://youtu.be/ca20JkKFAcE
My "People's Research Center" property is 7 acres and the soil is a heavy clay-loam, which has been a real problem because of the poor drainage.
I've thought about using this soil for pottery making and even tried firing some of this dirt in the wood stove with results that looked promising, but the impurities in the "clay" straight from the ground resulted in a lot of cracking and blackening from organic matter burning off and such though this "primitive" look was nice, the structure of the pottery was too porous and cracked to be practically useful.
I only had a vague idea the clay might be extracted from the "dirt", by letting it settle out in water, but thought it would probably be too much trouble.
The guy in this video, though, makes it look relatively easy!
I may start making some ceramic Stirling engines using local native clay from our own land.
Re: Making Glass and Ceramic Stirling engines
Just got back from digging down to the subsoil for some clay.
It's pretty heavy dark stuff with some lighter orange in spots.
I might try processing some this evening to see what the actual yield of clay might be. Then I guess I'll try making something with it and see how it fires in the kiln, but that probably won't be for a few days.
It's pretty heavy dark stuff with some lighter orange in spots.
- Resize_20230822_194459_9274.jpg (279.76 KiB) Viewed 8997 times
- Resize_20230822_194458_8407.jpg (260.02 KiB) Viewed 8997 times
- Resize_20230822_194456_6871.jpg (224.71 KiB) Viewed 8997 times
I might try processing some this evening to see what the actual yield of clay might be. Then I guess I'll try making something with it and see how it fires in the kiln, but that probably won't be for a few days.
Re: Making Glass and Ceramic Stirling engines
I think I'm done straining out the grass, roots and sticks, as well as letting the rocks and gravel settle out:
I started with five big chunks like this:
Crushed it all up in half a 5 gallon bucket of water then strained it through one of my paper making screens to get out floaty stuff.
Then let it settle a while to get out the gravely stuff:
Really both at the same time.
I repeated this a few times just pouring the liquid clay back and forth between two buckets through the screen and taking out whatever didn't go through the screen or that settled to the bottom of the bucket each time.
The liquid clay looks quite a bit lighter in color than the original clumps. A lot of the sand that settled out was very dark as can be seen above.
The liquid clay is kind of coffee with cream colored
I'd say, after screening and settling, the yield of actual clay is quite good, probably 95%
Probably I could just screen the sand to get out the larger gravel and put it back in as your supposed to add sand to the clay anyway. That black sand is probably not silica sand though. I may try that next time as I already threw the gravel and sand away.
Probably most of this "dirt" could be dry processed. Just to get out the bigger gravel, but I think this clay could mostly be used almost straight out of the ground.
I started with five big chunks like this:
- Resize_20230823_195325_5925.jpg (138.12 KiB) Viewed 8981 times
- Resize_20230823_195326_6904.jpg (151.86 KiB) Viewed 8981 times
Really both at the same time.
- Resize_20230823_195327_7790.jpg (156.1 KiB) Viewed 8981 times
The liquid clay looks quite a bit lighter in color than the original clumps. A lot of the sand that settled out was very dark as can be seen above.
The liquid clay is kind of coffee with cream colored
- Resize_20230823_195328_8547.jpg (126.78 KiB) Viewed 8981 times
Probably I could just screen the sand to get out the larger gravel and put it back in as your supposed to add sand to the clay anyway. That black sand is probably not silica sand though. I may try that next time as I already threw the gravel and sand away.
Probably most of this "dirt" could be dry processed. Just to get out the bigger gravel, but I think this clay could mostly be used almost straight out of the ground.
Re: Making Glass and Ceramic Stirling engines
I've been letting the liquid clay settle in the bucket in order to pour off the water.
It's been, I think, over twelve hours, but virtually nothing has happened.
The clay seems to have formed a gel-like colloidal suspension and is not settling.
There is just about maybe 1/16" to 1/8" or so of perfectly clear liquid above this thick gel.
From what little I've been able to find on the subject, outside it's use in cosmetics and medicine, a colloidal clay is a good thing.
It means the clay particles are extremely fine. So small and light that they can stay suspended in water indefinitely and make high quality ceramic that is naturally waterproof.
This kind of makes sense, as the soil in the area does not drain after a rain. Puddles will just lay on the ground until they evaporate.
It looks like I'm going to have to make a plaster of Paris table to absorb the water out of this stuff, which is probably a very worthwhile thing to do anyway.
Another reason it might be better to dry process the stuff, but from past experience, when dry, this soil gets incredibly hard. I've had to use a pickaxe on it many times when trying to dig, and that was when it is still relatively soft, still in the ground. When really dry it gets hard as rock and even with a pickaxe you can only chip away at it.
Dry processing I'm afraid could be very time consuming and labor intensive.
It's been, I think, over twelve hours, but virtually nothing has happened.
- Resize_20230824_104244_4487.jpg (172.55 KiB) Viewed 8964 times
The clay seems to have formed a gel-like colloidal suspension and is not settling.
There is just about maybe 1/16" to 1/8" or so of perfectly clear liquid above this thick gel.
From what little I've been able to find on the subject, outside it's use in cosmetics and medicine, a colloidal clay is a good thing.
It means the clay particles are extremely fine. So small and light that they can stay suspended in water indefinitely and make high quality ceramic that is naturally waterproof.
This kind of makes sense, as the soil in the area does not drain after a rain. Puddles will just lay on the ground until they evaporate.
It looks like I'm going to have to make a plaster of Paris table to absorb the water out of this stuff, which is probably a very worthwhile thing to do anyway.
Another reason it might be better to dry process the stuff, but from past experience, when dry, this soil gets incredibly hard. I've had to use a pickaxe on it many times when trying to dig, and that was when it is still relatively soft, still in the ground. When really dry it gets hard as rock and even with a pickaxe you can only chip away at it.
Dry processing I'm afraid could be very time consuming and labor intensive.
Re: Making Glass and Ceramic Stirling engines
Out of curiosity, I thought, maybe there is just a thin colloidal suspension on the top and the actual good clay has really all settled to the bottom in a thick layer. After all, I really have quite a lot of clay in just half a bucket of water.
So I took my stirring stick and tried to carefully scrape up the thicker sediment from the bottom of the bucket. I thought I might be able to feel the thicker "mud" on the bottom with the stick.
I couldn't "feel" anything on the bottom and scraping the stick across the bottom to try to get up something that had settled, there was nothing. The stick came out clean.
It is literally ALL colloidal suspension.
Still, I'll leave it a few days and see what happens. In the mean time I'll be making the plaster slab table.
So I took my stirring stick and tried to carefully scrape up the thicker sediment from the bottom of the bucket. I thought I might be able to feel the thicker "mud" on the bottom with the stick.
- Resize_20230824_113431_1369.jpg (192.84 KiB) Viewed 8962 times
I couldn't "feel" anything on the bottom and scraping the stick across the bottom to try to get up something that had settled, there was nothing. The stick came out clean.
It is literally ALL colloidal suspension.
Still, I'll leave it a few days and see what happens. In the mean time I'll be making the plaster slab table.
Re: Making Glass and Ceramic Stirling engines
It looks like I quite possibly could be making a lot of this clay in the future, so I'm making a fairly big plaster table.
I'm going to try making the bottom of the slab ribbed for extra surface area and faster drying.
- Resize_20230824_172030_0304.jpg (114.03 KiB) Viewed 8951 times
Re: Making Glass and Ceramic Stirling engines
Maybe the channels on the bottom will help keep the slab dryer. Probably couldn't hurt anyway.
- Resize_20230824_185526_6763.jpg (207.63 KiB) Viewed 8943 times
Re: Making Glass and Ceramic Stirling engines
This is kind of odd.
The clay suspension, with still just a thin layer of clear water on top, has formed into a kind of mass seperated from the walls of the bucket, almost like jello separating from a jello mold.
- Resize_20230827_154316_6443.jpg (212.99 KiB) Viewed 8889 times
The clay suspension, with still just a thin layer of clear water on top, has formed into a kind of mass seperated from the walls of the bucket, almost like jello separating from a jello mold.
Re: Making Glass and Ceramic Stirling engines
I've been able to pour off a little water every two or three days.
The big plaster slab seems like it's still a bit damp, but solid enough to handle and carry around so I took it out of the form and set it in a warmer spot where it can get more air circulation and dry out faster.
In the mean time, while that big slab dries I did find some plaster dried up in the bottom of a bucket, left over from a project from a few years ago, so it is good and dry but not very big.
I was able to ladle some liquid clay onto that. The plaster should draw the water out of the clay very rapidly, so I should have a small clay sample to work with and try out in an hour or two.
Wow that plaster works fast!
It's only been like five minutes and I still had time to edit the post!
As can be seen the clay is already starting to dry around the edges quite nicely!
The big plaster slab seems like it's still a bit damp, but solid enough to handle and carry around so I took it out of the form and set it in a warmer spot where it can get more air circulation and dry out faster.
In the mean time, while that big slab dries I did find some plaster dried up in the bottom of a bucket, left over from a project from a few years ago, so it is good and dry but not very big.
I was able to ladle some liquid clay onto that. The plaster should draw the water out of the clay very rapidly, so I should have a small clay sample to work with and try out in an hour or two.
- Resize_20230907_213225_5041.jpg (103.09 KiB) Viewed 8814 times
- Resize_20230907_215032_2313.jpg (88.02 KiB) Viewed 8813 times
As can be seen the clay is already starting to dry around the edges quite nicely!
Re: Making Glass and Ceramic Stirling engines
I can see why using a plaster slab is a widely used method for drying liquid clay.
It works great. The clay dries out fast and peels right off clean, ready for another batch.
It works great. The clay dries out fast and peels right off clean, ready for another batch.
- Resize_20230907_235106_6962.jpg (101.62 KiB) Viewed 8805 times
- Resize_20230907_235214_4005.jpg (124.37 KiB) Viewed 8805 times
- Resize_20230907_235335_5301.jpg (121.03 KiB) Viewed 8805 times