Post by mintcake on May 14, 2014 9:59:33 GMT -8
Hi,
I've just been about to do some more experimental batches trying to find out about how much waterglass I should add to my mixes. So far, I've only made little bricks, my intention was to find out any particular mix survived better as something closer to stove-shape. Using what came to hand I decided to use some 4cm square section steel and a cottage cheese pot. Hopefully, thought I, this will give me a repeatable shape which will show cracking etc. well.
I started with 50-50 clay-perlite mixture, but accidentally added too much water, and it ended up quite runny. I bit the bullet and tried to remove the steel from the form; it slumped badly.
Odd, thought I, I don't remember ever getting a mix this runny when I had waterglass in the mix.
So, I added a capful of waterglass. I should have put it into the mold quicker, because after about twenty seconds, I didn't have a runny mixture any more, I had something more like toothpaste. By the time I was trying to put it into the form, it wouldn't let go of my trowel, and I had to scrape it in. It's certainly thicker than toothpaste now, more like a hardish mashed potato consistency.
I tried my prototype vibrating table (probably not enough vibration) and it just sat there and ignored gravity. I got air-pockets and probably should have tried to ram it in. As it was, I decided to try troweling it on. It stayed put on the form, and was fairly easy to shape. No slumping when I took out the form. For the sake of scientific enquiry I turned on the vibrating table, which had made short work of the mix before. It ignored me again. So... a dash of waterglass turns over-runny clay-perlite into something akin to mashed potato. I guess that when the water evaporates I'm going to end up with something crumbly, since there was so much water in the mix, and I'm starting to worry about getting the mixture into my eventual mold.
But... does anyone know what's happening?
I've just been about to do some more experimental batches trying to find out about how much waterglass I should add to my mixes. So far, I've only made little bricks, my intention was to find out any particular mix survived better as something closer to stove-shape. Using what came to hand I decided to use some 4cm square section steel and a cottage cheese pot. Hopefully, thought I, this will give me a repeatable shape which will show cracking etc. well.
I started with 50-50 clay-perlite mixture, but accidentally added too much water, and it ended up quite runny. I bit the bullet and tried to remove the steel from the form; it slumped badly.
Odd, thought I, I don't remember ever getting a mix this runny when I had waterglass in the mix.
So, I added a capful of waterglass. I should have put it into the mold quicker, because after about twenty seconds, I didn't have a runny mixture any more, I had something more like toothpaste. By the time I was trying to put it into the form, it wouldn't let go of my trowel, and I had to scrape it in. It's certainly thicker than toothpaste now, more like a hardish mashed potato consistency.
I tried my prototype vibrating table (probably not enough vibration) and it just sat there and ignored gravity. I got air-pockets and probably should have tried to ram it in. As it was, I decided to try troweling it on. It stayed put on the form, and was fairly easy to shape. No slumping when I took out the form. For the sake of scientific enquiry I turned on the vibrating table, which had made short work of the mix before. It ignored me again. So... a dash of waterglass turns over-runny clay-perlite into something akin to mashed potato. I guess that when the water evaporates I'm going to end up with something crumbly, since there was so much water in the mix, and I'm starting to worry about getting the mixture into my eventual mold.
But... does anyone know what's happening?