Sciencemadness Discussion Board - sodium silicate from silica sand and sodium hydroxide solution in water for making calcium silicate

sodium silicate from silica sand and sodium hydroxide solution in water for making calcium silicate

nikotyna1939 - 22-8-2025 at 22:45

Recently i decided to make sodium silicate or water glass at home by using sodium silicate from finely crushed silica sand and sodium hydroxide solution in hot water temperature about 90 Celsius
I'm making sodium silicate through dissolving 1.5 kg NAOH in 1 liter hot water and 500 gram of aquascape grade silica sand at pp plastic container.
I wanted to know whether can I react sodium silicate in water solution with Calcium oxide to produce calcium silicate brick at home for small scale foundry or oven insulation about under 1 kg of calcium silicate for testing uses.
I wondered why the NAOH solution doesn't just dissolve all the silica sand while there is some sediment still at the bottom.
Also what is the best method to purify sodium silicate solution from the unreacted silica and NAOH at home
PS I DON'T JUST BUY THE CALCIUM SILICATE INSULATION BECAUSE THE SHIPPING FEE AND THE MINIMUM QUANTITY TO BUY IS TOO EXPENSIVE PER KG THAN BUYING CALCIUM OXIDE AND SILICA SAND PER KG.

i heated again the NAOH and sicila sand solution

nikotyna1939 - 23-8-2025 at 01:10

Few hours later i heated again the NAOH and silica sand solution at 90 celsius
The sediment solids it became decreasing but this is what i got
I wondered is this solids an unreacted silica and NAOH?
Did the sodium silicate become soluble in water?
Why there is a crystal floating on the top of the solution?
What kind of compound is the crystal floating on the top of the solution?

bnull - 23-8-2025 at 05:16

A suggestion. Try small scale first. If you wanted to oxidize glycerol with calcium hypochlorite, a small scale test (1 g or so) would show that the result is a toxic smoke and possibly fire. If you went large scale first, you'd be saying goodbye to your lungs.

What is the temperature at the top of the, um, sludge?

Do not use an aluminum cooking pan to heat corrosive substances, even if they're inside another container. Especially if the corrosive substance is an alkali. Edit: It looks like stainless steel but my advice about aluminum still stands.

Remove the crystal and see if it soluble in water. If so, add a few drops of copper sulfate. If the blue solid formed refuses to dissolve when you acidify the solution, then the crystal is a sodium silicate.

Quote:

PS I DON'T JUST BUY THE CALCIUM SILICATE INSULATION BECAUSE THE SHIPPING FEE AND THE MINIMUM QUANTITY TO BUY IS TOO EXPENSIVE PER KG THAN BUYING CALCIUM OXIDE AND SILICA SAND PER KG.

I'd be willing to bet $ 20 that you'll end up spending that much or even more with homemade calcium silicate.

[Edited on 23-8-2025 by bnull]

Cathoderay - 23-8-2025 at 07:07

As it happens I just made a small amount of sodium silicate solution last week.
I used the NurdRage method.
https://www.youtube.com/watch?v=xltvwhogklI

That used silica gel packs that I had collected over time. I ground the silica gel to a fine powder and added it gradually as it dissolved. It is a slow process.
I did it in a small borosilica breaker. (You would think the beaker would be attacked but it wasn't.) I think I ran it at about 65 C. Stirred constantly.
NurdRage has another video where he used crystal cat litter.

Are you sure of the temperature in your reaction?
Sand would probably dissolve even slower.

Radiums Lab - 23-8-2025 at 11:47

I won't recomend you to use CaO as pulling Na+ becomes difficult. Use Chloride insteard.

cost of chemicals in my country

nikotyna1939 - 24-8-2025 at 01:37

the cost of chemicals in indonesia is very cheap
The price of 1 KG silica sand is Rp 4500 or 0.28 USD at now current exchange with free shipping fee..
The price of 1 KG Calcium oxide or kapur tohor in the local language is Rp 4299 or 0.26 USD at now current exchange with free shipping fee.
But the price of 25 kg of calcium silicate block is RP 520000 OR 32.04 USD excluding shipping fee.
Currently I'm planing to make about 17 kg of calcium silicate square block with tubular hole inside for the insulation of small scale electric arc foundry.

[Edited on 24-8-2025 by nikotyna1939]

material for containing the sodium hydroxide and silica solution

nikotyna1939 - 24-8-2025 at 01:45

i used thick pp plastic container in boiling water bath with stainless steel pot to perform the procedure.

how much copper sulfate percentage solution drops and ph to acidify the solution?

nikotyna1939 - 7-9-2025 at 16:05

Quote: Originally posted by bnull

A suggestion. Try small scale first. If you wanted to oxidize glycerol with calcium hypochlorite, a small scale test (1 g or so) would show that the result is a toxic smoke and possibly fire. If you went large scale first, you'd be saying goodbye to your lungs.

What is the temperature at the top of the, um, sludge?

Do not use an aluminum cooking pan to heat corrosive substances, even if they're inside another container. Especially if the corrosive substance is an alkali. Edit: It looks like stainless steel but my advice about aluminum still stands.

Remove the crystal and see if it soluble in water. If so, add a few drops of copper sulfate. If the blue solid formed refuses to dissolve when you acidify the solution, then the crystal is a sodium silicate.

bnull - 8-9-2025 at 04:34

Quote:

how much copper sulfate percentage solution drops and ph to acidify the solution?

Forget it. It doesn't look like it will work: the result will probably be a sludge of copper hydroxides and silica gel.

Edit: But you can use only the acid and see if, after you have dissolved the crystals in water, silica gel precipitates. Gather a good quantity of the floating crystals, dissolve them in the smallest quantity of water, put the solution on a piece of flat glass (microscopy glass slide or the glass plate of a photo frame), add acid and see if something precipitates.

[Edited on 8-9-2025 by bnull]

clearly_not_atara - 8-9-2025 at 04:36

Isn't MgO also a pretty good refractory? Seems like that should be an awful lot easier to make than CaSiO4.

bnull - 8-9-2025 at 05:08

I think I'm beginning to see a problem with the whole calcium silicate thing. It will crumble to pieces. Calcium silicate bricks are not made from pure calcium silicate and simply shaping calcium silicate into bricks and somehow firing them at home won't work.

You need to consider alternatives, @nikotyna1939. What is old is new again:

Quote: Originally posted by bnull

Here is an article: E. A. Ginzel, Steel in Ancient Greece and Rome.

Reason of using calcium silicate

nikotyna1939 - 10-9-2025 at 22:16

the main reasons i used calcium silicate is
1.its doesn't easily dissolves in water
2.its has very low thermal conductivity generally in the range of 0.05 to 0.15 W/(m·K) at room temperature
i wanted to use calcium silicate because i believe it will kept the heat from wasting away like a jacket that keeps you warm.

bnull - 11-9-2025 at 06:03

What binder are you going to use with the silicate?

calcium silicate aggregate with refractory cement as the binder

nikotyna1939 - 20-9-2025 at 05:04

I'm planning to make dicalcium silicate (2cao·sio2) for the aggregate with refractory cement as the binder to create a very good and efficient insulator brick for the small scaled furnace that I'm planning to make

The main uses of the small-scale furnace that I will build

nikotyna1939 - 21-9-2025 at 00:33

I'm planning to melt primarily borosilicate glass at the maximum temperature and melt zinc at the lowest temperature in my backyard.
PS THE REASONS I NEED TO MAKE BOROSILICATE GLASS EQUIPMENT IN MY BACKYARD WAS THAT I WANT TO BUILD A VERY CUSTOMIZED AND COMPLEX REQUIREMENT FOR THE BOROSILICATE GLASS EQUIPMENT

bnull - 21-9-2025 at 04:48

Now that the need for calcium silicate is fully explained, let's get this straight, and off-topic as well. Consider the following a sort of checklist; only advance to the next item if you have completed the previous items.

Have you ever operated a furnace or oven, however small and inefficient it was?
Do you have any experience with high temperatures, like those achieved with a blowtorch?
Do you have any experience with glassblowing? Can you show us a picture of a glass object blown by you yourself without someone else's help?
Do you have any experience with scientific glassblowing? If so, can you provide us with pictures of the glassware you made?
Do you have pictures that show the strain on the glass objects you made? See Strain Testing Glass for a simple setup.
Did your homemade glassware work as intended? Was there any malfunction?

You're not intending to make your own borosilicate glass from sand etc., are you?

Melting (in the sense used by glass manufacturers, not the physico-chemical one; there was a rather long discussion on semantics last year and I'd rather not see it again) borosilicate glass and working it is no easy task. Otherwise we'd have kicked most of the companies out of business.

Amateur chemistry involves not only building equipment from scratch but also adapting already existent equipment^*. I wanted a condenser for test tubes for my semimicro experiments. Instead of buying one and messing my budget for a few months, I opted for a boro glass tube sold as level indicator in coffee machines. It doesn't beat a commercial condenser but it works.

*: The non-scientific part of amateur science depends on these four principles: adapt, build, buy, fix. You can adapt equipment not originally intended for the use you want, you can build equipment for already existent or new functions, you can buy equipment, and you can fix equipment that you bought or found or received as a gift. The real fun comes when you apply all the four principles. Source: yours truly.

Edit: Tweaked to sound less harsh. Blood pressure's a bit high today.

[Edited on 21-9-2025 by bnull]

violet sin - 4-10-2025 at 13:46

youtu.be/XCI_FPDQA-U?si=F0SX7ELgbPnOjD_T
Shake the future

I've just found this guy recently, and wow, what a game changer for small foundry and glass work. He manages to make a lot of his stuff, does it on a balcony and seems pretty safety oriented.

Ceramic fiber insulation, kapton tape, silicon carbide powder, waterglass, plaster and a microwave. Managed to make the molds, crucible, kiln, in a number of different configurations for glas/metal/mold burnout

Cool files to 3d print, I mean this guy has a wealth of knowledge, it's been a treat to watch/listen on earbuds while packing boxes at work.

Would it help with glass blowing, prob not. Are there parts that could be used, probably.

Also recently, I came across this video
youtu.be/ilcDT3GQlRw?si=OB9uq-7tdFN99L62
thoisoi2,

where he makes some cool UV glow glasses. In the process, a few different recipes for glass were tried and I found that interesting, how easily he was able to whip up a batch of rare earth oxide doped glass, that were attractive in appearance. Very encouraging for the weekend warrior.

While none of that is super relevant, I feel it is worth sharing in case it crosses into anyone's other hobbies or endeavors.

Somewhere I have an ancient sodium aluminate experiment, and some sodium silicate from lye with diatomaceous earth. Magnesium oxide and alumina were made too.

He directly rams SiC dust with 8-10% sodium silicate solution and fires in the microwave, so I've either got a find my old experiment or make som more. Lye with an excess of diatomaceous earth, made a pretty strong solution if I recall correctly. Just pour it off.

Good luck gentlemen, keep a fire extinguisher handy

macckone - 4-10-2025 at 14:09

If you are looking for cheap insulation for a furnace, buy rockwool at any home improvement store. It is good to about 1100 to 1200C. Not to be confused with fiberglass. Rockwool is literally melted rock (slag) from iron refining to pig iron. Which is then further refined in a more carefull manner in an oxygen furnace.

metalresearcher - 5-10-2025 at 11:18

Quote: Originally posted by macckone

If you are looking for cheap insulation for a furnace, buy rockwool at any home improvement store. It is good to about 1100 to 1200C. Not to be confused with fiberglass. Rockwool is literally melted rock (slag) from iron refining to pig iron. Which is then further refined in a more carefull manner in an oxygen furnace.

Rockwool is not heat resistant above ca 1000 C, so it won't stand the heat in most furnaces.
Get Kaowool or the similar Fiberfrax, which is actually ceramic fiber. It is used in many commercial furnaces. Don't forget to line it with a rigidizer (e.g. Satanite or Fermit) after constructing your furnace, as the fibers may otherwise fly around and inhaling them is almost as bad as asbestos fibers.

violet sin - 5-10-2025 at 11:46

I'm not sure about how easy people can find ceramic fiber blanket roll, but I did not find it challenging. Ithe thing was like 85$-100$ next day on my porch, through zoro a few years back. 25' roll of 24" x 1"

I've seen 1 and 2 foot squares on eBay before, for a statistically significant portion, of the price I paid for a whole roll... So keep your eyes open. I didn't exactly want to spend that much on one item, but it will serve me for a long time, through several projects, and in the end it was a great value

bnull - 10-10-2025 at 14:25

I was browsing the 14th edition of the Merck Index yesterday and, to my surprise (it's the Merck Index, so I should not have been surprised at all), calcium silicate was there.

Quote:

The usual method of prepn is from lime and diatomaceous Earth under carefully controlled conditions: Boss, Chem. Eng. News 27, 677 (1949); Steinour, Chem. Rev. 40, 391 (1947).

A. Evan Boss, Adaptability, a Tool for Production Development (https://doi.org/10.1021/cen-v027n010.p677); Harold H. Steinour, The System CaO-SiO₂-H₂O and the Hydration of Calcium Silicates, (https://doi.org/10.1021/cr60127a003).

changed my mind about the borosilicate glass

nikotyna1939 - 18-10-2025 at 21:45

Recently after reading and asking on Google ai i decided to just buy the borosilicate glass equipment
But for the foundry that im planning to built is primarily for melting metals like aluminium ,zinc ,copper, nickel, cobalt, manganese and other metals under 1800 celsius.

No fiber based insulation please

nikotyna1939 - 18-10-2025 at 21:50

the reasons that i don't want to use fiber based insulation because it could release the fiber particle into the air.