I cook mine in one of those counter top small ovens. I tried gas but i kept getting a soft spot in the center so i took the oven approach. Throw in the small oven, at low temperature, it works great.
A very nice alternate sodium silicate curing method. It seems like from these two tests, the user only needs to vary the microwave time according to the volume of material to be cured. I imagine, using a lower power setting on the microwave and a longer duration might allow more even exposure and complete solidification for larger and more complex shapes with less concern for developing hot spots and such where heat may tend to concentrate.
Yes you are right not all cores are the same shape and volume, also using a different microwave oven might give different results. SS is very cheap so you can afford to do some experiments to get the results you want.
Hi ironman, vtsteam here. Just a guess, but if you know the weight of your core sand, the time needed to harden might be fairly proportional to that. The ideal would be hard enough, but not so long that it affects the plastic -- as you say. Maybe you can do a few different weight sand experiments with your oven and plot a simple graph vs time of the successes. That would give a rule of thumb for future cores.
You probably just needed to thump the door on that microwave a bit. You closed the door kind of gentle and might not have triggered the door safety switch. Our old one gets like that. Just have to make sure and close it firmly.
I've had some success curing silicate cores in a toaster oven. My plaster corebox became quite brittle however... So the use of a thicker sodium silicate that is viscous enough to allow demolding of unhardened cores worked the best for heat curing in my experiments, but one day I'd like to try building a plaster corebox with shrink allowance built in for aluminum and cast corebox halves that can survive being baked...
If you have a close look at the plaster core box there are many cracks because microwaves tend to dry it out. Before using a plaster core box spray water on it so it loses less water when heated.
Water is chemically part of the plasture structure when hardened. Heating cured plaster is driving the water molecule out. Carbon dioxide is blown into the sand core and reacts with NaOH to form Na2CO3, thus increasing the sodium silicate modulus. Heating the sodium silicate is just mechanically driving out the water, making the silica gel , more thick. And destroying your plaster mold at the same time.
@luckygen1001 Is there any benefit of "carbon-blacking" or graphite covering the core for surface finish over the sodium silicate core? Thought it may be a bit of overkill- but core stability is one factor- surface finish is another...
Great point, it does make a lot difference to the surface finish using graphite to fill in the space between sand grains. Have a look at my video "Portland cement as a sand binder" it shows how I rub graphite into the sand pores. Wear gloves as graphite is very dirty.
Is that a plaster core box? (first core) I have sodium silicate but have not used it yet because of the lack of a good C02 source. I now with this, I will go and give it a try. Thanks.
Great idea! I just inherited an extra microwave. Is it worth or could one reuse the (sand) silicate core? Or will having used the sand cause some sort of contamination due to the sand having been coated once?
Sand is so cheap so it is not worth reusing core sand. Also if you reuse core sand there is a build up of sodium silicate which does not burn up and you have to use more sodium silicate to rebind the sand.
would it be possible to generate CO2 by heating baking soda sodium bicarbonate in the microwave to increase efficiency? Could you use baking soda sprinkled over the mold as a release agent?
You can use sodium bicarbonate in another container and add vinegar to produce CO2 then run a hose to the core. Heating it up without directing CO2 to the core gives poor results.
All core binders will out gas combustion vapours just look at green sand, if too much binder or water is used there will be problems. The trick is to keep the binder or water under a level that causes problems (blowholes).@@honthirty_
Some random thoughts. I've played with heating sodium silicate a little bit. Using a wooden core box would work, but the box may experience some warping due to the water that will boil off of the core. It might also raise the grain in the wood and make removal difficult. I wouldn't cook a wooden core box for which I had a lot of time invested. If you paint your core boxes, the paint is likely to fail from the temperature. A metal core box (i.e., piece of copper pipe) could be used in a conventional (not microwave) oven rather than the PVC pipe in a microwave for a round core.
I think simple cores that are round and an easy job to make in the lathe using wood is the go as you said complicated wooden core boxes could be used later if the simple cores do work.
Hi! I am from Austria, so my request what is Sodiumsilicat? We have here , NaSiO? or is it , oder is it Natriumwasserglas, Kaliumwasserglas oder Lithiumwasserglas.
Hello and Happy New Year =) 09:20 - Why don't you put an item in the center? Is it specifically or without any thought? I am not a specialist, but it seems to me that the most powerful heating should be in the center - there the subject is constantly under the heating. And when the item stands on the edge of the plate, then it enters the center only at two points. p.s. It is interesting, and if you use glass tubes for chemical experiments or glass tubes that are sold for hobbists, they are heated by a direct flame of a gas burner. But if the sodium silicate expands, then the glass can burst. p.p.s. I'm using google translate, If something is incomprehensible, ask me, I will try to paraphrase
I had a look at my kitchen microwave oven user manual and it does not say anything about where to place food on the dish to heat up. As the dish rotates it will heat up food evenly. Google translate did an excellent job translating Russian to English.
@@luckygen1001 It would be necessary to check in a practical way. I think you need to take two identical glass mugs, pour the same amount of water from one source (stir in a jar). Put one mug in the center of plate in microwave, and the other on the edge. And then check the temperature sensor. I wonder if there will be a difference or not =) p.s. *Google translate did an excellent job translating Russian to English* - cool!)
I did what you suggested and heated 0.2 liter of water for 2 minutes with the container in the middle, The temperature got to 93 C. I heated another 0.2 liter of water but did not put it in the middle and the max temperature was 87 C. So there is a difference but not much.@@pinokio514
@@luckygen1001 Super, thanks for the test! I think that the temperature difference has changed slowly. That is, when the mug in the center was heated to 20 degrees, the difference was 1-2 degrees. When heated to 40, the difference was 2-3 degrees. And so on. Perhaps this difference will be significant if you melt the metal in the microwave. Or if you heat a large volume of liquid or something. And this can affect the time and electricity. p.s. On a non-working microwave the buttons or sensors? If the buttons, then you can buy a set of conductive rubbers for remote control and try to fix the microwave. I saw in UA-cam how they glue aluminium foil instead of these rubbers in remote controls for TV. But first, it is better to open the microwave and see what is there. Before buying something.
Please keep making your videos sir
You're an amazing human
It's just a matter of time before your channel gets huge (again)
Thank you
I cook mine in one of those counter top small ovens. I tried gas but i kept getting a soft spot in the center so i took the oven approach. Throw in the small oven, at low temperature, it works great.
To get rid of that soft spot in the center push a thin piece or wire in the center of the core and that soft spot will disappear.
A very nice alternate sodium silicate curing method. It seems like from these two tests, the user only needs to vary the microwave time according to the volume of material to be cured.
I imagine, using a lower power setting on the microwave and a longer duration might allow more even exposure and complete solidification for larger and more complex shapes with less concern for developing hot spots and such where heat may tend to concentrate.
Apparently, microwave is one of three main ways to cure sodium silicate when used for foundry work?
en.wikipedia.org/wiki/Sodium_silicate#Foundry
Yes you are right not all cores are the same shape and volume, also using a different microwave oven might give different results. SS is very cheap so you can afford to do some experiments to get the results you want.
Great idea! Almost looked like a cooking lesson for a Christmas cake :-) Happy New Year!!
Thanks for watching.
@@luckygen1001 👍
Always interesting and well explained
Really interesting, thanks. Good to see what can go wrong as well.
thank you sir
Hi ironman, vtsteam here. Just a guess, but if you know the weight of your core sand, the time needed to harden might be fairly proportional to that. The ideal would be hard enough, but not so long that it affects the plastic -- as you say. Maybe you can do a few different weight sand experiments with your oven and plot a simple graph vs time of the successes. That would give a rule of thumb for future cores.
Different sized cores would need more time for it to harden so plastics may not be able to be used.
Thanks for sharing 👍
Thanks for watching.
This is absolutelt awesome. But might I suggest adding ceramic ejector pins to your mold.
Would be nice to use ceramic pins if I could get them.
@@luckygen1001 mcmaster in the states carries "machine-able ceramic" 1/4"dia 3" long pins for $17.80usd per.
excellent vid thanks
You probably just needed to thump the door on that microwave a bit. You closed the door kind of gentle and might not have triggered the door safety switch. Our old one gets like that. Just have to make sure and close it firmly.
It was not the door switch because no matter which button I pressed the display would not show a change.
Wish you would have broken them for a strength test. Crushing, bending and scraping.
I've had some success curing silicate cores in a toaster oven. My plaster corebox became quite brittle however... So the use of a thicker sodium silicate that is viscous enough to allow demolding of unhardened cores worked the best for heat curing in my experiments, but one day I'd like to try building a plaster corebox with shrink allowance built in for aluminum and cast corebox halves that can survive being baked...
If you have a close look at the plaster core box there are many cracks because microwaves tend to dry it out. Before using a plaster core box spray water on it so it loses less water when heated.
Water is chemically part of the plasture structure when hardened.
Heating cured plaster is driving the water molecule out.
Carbon dioxide is blown into the sand core and reacts with NaOH to form Na2CO3, thus increasing the sodium silicate modulus. Heating the sodium silicate is just mechanically driving out the water, making the silica gel , more thick. And destroying your plaster mold at the same time.
that's sure more convenient than using my brewing C02 to harden cores.
Used CO2 for years but the cost made me look for an alternate way of hardening cores.
There used to be an ester hardner for Sodium Silicate that I used many years ago, not sure if it's still available though. Microwave works well.
I'm picturing a miniature Kooka miller for mixing the sand.
@luckygen1001 Is there any benefit of "carbon-blacking" or graphite covering the core for surface finish over the sodium silicate core? Thought it may be a bit of overkill- but core stability is one factor- surface finish is another...
Great point, it does make a lot difference to the surface finish using graphite to fill in the space between sand grains. Have a look at my video "Portland cement as a sand binder" it shows how I rub graphite into the sand pores. Wear gloves as graphite is very dirty.
Is that a plaster core box? (first core) I have sodium silicate but have not used it yet because of the lack of a good C02 source. I now with this, I will go and give it a try. Thanks.
Yes it was. I did not try a wood core box in the video but it should work.
Great idea! I just inherited an extra microwave. Is it worth or could one reuse the (sand) silicate core? Or will having used the sand cause some sort of contamination due to the sand having been coated once?
Sand is so cheap so it is not worth reusing core sand. Also if you reuse core sand there is a build up of sodium silicate which does not burn up and you have to use more sodium silicate to rebind the sand.
would it be possible to generate CO2 by heating baking soda sodium bicarbonate in the microwave to increase efficiency? Could you use baking soda sprinkled over the mold as a release agent?
You can use sodium bicarbonate in another container and add vinegar to produce CO2 then run a hose to the core. Heating it up without directing CO2 to the core gives poor results.
I wonder if eggs could be used instead of sodium silicate? Happy New year Lucky 👍👍👍
Eggs are a great binder. Eggs are used to bind food like egg and flour.
All core binders will out gas combustion vapours just look at green sand, if too much binder or water is used there will be problems. The trick is to keep the binder or water under a level that causes problems (blowholes).@@honthirty_
Molasses works great as a binders baked in an oven makes a nice core. Not sure if it will harden in a microwave though.
Some random thoughts. I've played with heating sodium silicate a little bit. Using a wooden core box would work, but the box may experience some warping due to the water that will boil off of the core. It might also raise the grain in the wood and make removal difficult. I wouldn't cook a wooden core box for which I had a lot of time invested. If you paint your core boxes, the paint is likely to fail from the temperature. A metal core box (i.e., piece of copper pipe) could be used in a conventional (not microwave) oven rather than the PVC pipe in a microwave for a round core.
I think simple cores that are round and an easy job to make in the lathe using wood is the go as you said complicated wooden core boxes could be used later if the simple cores do work.
Hi, great idea, but could i use a regular oven and get the same results? Best wishes and all my regards 🙂
If the core mold lasts with a long heating time just use that method.
Thank you much. It's always a pleasure to watch your videos! @@luckygen1001
Hi! I am from Austria, so my request what is Sodiumsilicat? We have here , NaSiO? or is it , oder is it Natriumwasserglas, Kaliumwasserglas oder Lithiumwasserglas.
The term in English "sodium silicate" refers in this context to "sodium metasilicate", Na2SiO3, with the Na+ ion. You'd want to use Natriumwasserglas.
There are many kinds of sodium silicate use one that is made for foundry work. I use COOLSET1 and is made by foseco.
I was wondering about this, NOBOX tried to use water glass as a refractory and it acted like wax when heated.
SS is not a refractory and will breakdown with high heat.@@stoneomountain2390
Definitely *not* if the wife's around.
I would not use a microwave for cores and prepare food in it.
Hello and Happy New Year =)
09:20 - Why don't you put an item in the center? Is it specifically or without any thought? I am not a specialist, but it seems to me that the most powerful heating should be in the center - there the subject is constantly under the heating. And when the item stands on the edge of the plate, then it enters the center only at two points.
p.s. It is interesting, and if you use glass tubes for chemical experiments or glass tubes that are sold for hobbists, they are heated by a direct flame of a gas burner. But if the sodium silicate expands, then the glass can burst.
p.p.s. I'm using google translate, If something is incomprehensible, ask me, I will try to paraphrase
I had a look at my kitchen microwave oven user manual and it does not say anything about where to place food on the dish to heat up. As the dish rotates it will heat up food evenly. Google translate did an excellent job translating Russian to English.
@@luckygen1001 It would be necessary to check in a practical way. I think you need to take two identical glass mugs, pour the same amount of water from one source (stir in a jar). Put one mug in the center of plate in microwave, and the other on the edge. And then check the temperature sensor. I wonder if there will be a difference or not =)
p.s. *Google translate did an excellent job translating Russian to English* - cool!)
I did what you suggested and heated 0.2 liter of water for 2 minutes with the container in the middle, The temperature got to 93 C. I heated another 0.2 liter of water but did not put it in the middle and the max temperature was 87 C. So there is a difference but not much.@@pinokio514
@@luckygen1001 Super, thanks for the test!
I think that the temperature difference has changed slowly. That is, when the mug in the center was heated to 20 degrees, the difference was 1-2 degrees. When heated to 40, the difference was 2-3 degrees. And so on. Perhaps this difference will be significant if you melt the metal in the microwave. Or if you heat a large volume of liquid or something. And this can affect the time and electricity.
p.s. On a non-working microwave the buttons or sensors? If the buttons, then you can buy a set of conductive rubbers for remote control and try to fix the microwave. I saw in UA-cam how they glue aluminium foil instead of these rubbers in remote controls for TV. But first, it is better to open the microwave and see what is there. Before buying something.
It was the touch pad so I threw that microwave out, I have plenty of spare microwave ovens.@@pinokio514