How to Make Sodium Silicate - Water Glass

Intro: How to Make Sodium Silicate - Water Glass

Sodium silicate, also called waterglass is an interesting compound that is used in a variety of things. Water glass is a glue, a high heat cement or refractory, used to preserve eggs without refrigeration and as a sealer for concrete. My interest is to use sodium silicate for a refractory in a high heat forge. It is commercially available but locally I was unable to find it in the concentration I needed. So I found some videos and information online and found out how to make my own water glass.

I was successful, so I thought I would share my experience.

Warning, this involves using a caustic ingredient and heat so wear appropriate safety equipment, face shield, gloves and work in a well ventilated area.

STEP 1: The Materials

You will need the following:

200 grams Sodium Hydroxide - commonly known as lye, you need the pure form, some drain cleaners are made from this, soap makers also use it.

300 grams Silica Gel - Found in those little do not eat packs that come with electronics, also used as cat litter.

500 ml Water

Heat Source - butane burner, camp stove, etc.

Long Stir Stick

Stainless steel bowl or pot

Well ventilated work space

STEP 2: Video of the Whole Process

Here is a video of the whole process.

STEP 3: Written Steps

Here are the steps:

Add the lye to the water, this will generate lots of heat and fumes, do this in a well ventilated area.

Once mixed add a little silica gel to the mixture, this will react and create more heat and fumes, stir to mix.

Keep adding a little of the silica gel at a time to the mixture until it is al combined. It is ok if the silica gel does not dissolve.

Heat the mixture over your heat source until it boils and keep stirring. If it starts over boiling, turn down the heat. Keep stirring and eventually it will become a clear thick syrup. If the silica gel has coloring in it, it may have a tint to it, which is perfectly ok.

Let cool and store. It can be diluted with water depending what your application is.

Here is the original video that I used as reference

https://www.youtube.com/watch?v=-Mx1-o1_MWo

Comments

[mcleod3ca]

used water glass years ago, mixed it with silica sand and used co2 gas to set the waterglass and harden it to use as mold and cores for aluminum and bronze casting worked great.

[majidshahmoradi39]

If we mix it with sand,Then it gets hard?
Can it be used instead of resin?

[ElezibethA]

Safety first... aluminum and lye do NOT mix. Stainless is the preferred choice.

Also, depending on wether or not you use crystal or bead sodium hydroxide, you may need to stir the lye into the water continuously for up to a few minutes to dissolve completely. Wear gloves. The water can get so hot that tiny splatters come up and catch the back of your hand, which hurts like heck, mostly later.



As for things not dissolving completely: lye will not (stay) dissolved at lower temperatures at a ratio greater than 1:1 with water.

For the ratio, this would appear to be a 50% water glass solution, but I believe it’s much higher than that. (Sort of... some things aren’t dissolving/reacting)

1st reason: heat will generate steam, and boiling will lower the water quantity only. Water glass is sold as 40% because that’s the highest concentration feasible to adequately dissolve the chemicals into solution.

So, my recommendations are this:
1. Obtain chemical resistant gloves and apron and non-vented Z-71 or higher rated safety goggles.
2. Remove all children and pets from area.
3. Wear long sleeve shirts, long pants. And SHOES.
4. Have adequate running water available and towels you don’t mind ruining to clean up spills.
5. Ensure all utinsils are NOT ALLUMINUM. Or glass(sodium hydroxide can etch glass.) Just get some stainless, ideally.
6. Don’t work alone.
7. ALWAYS add sodium hydroxide to water. NEVER ADD WATER TO SODIUM HYDROXIDE.
8. Weigh empty mixing/heating container prior to starting so you can weigh your solution when finished.
9. Add lye to cool water. It will heat up enough to dissolve the lye very quickly.

Increase water to 600 gm. (When working with lye, weighing liquids is more ideal for being able to find correct concentrations) for Total recipe. This should give you 20% more water to work with, improving solubility, and allowing for boil off. To further encourage proper solution making and reduce the risk of unknown reactions, use distilled water. (My well water is so hard that the reactions of whatever is in the water impede proper dissolving of lye at higher concentrations.)

Weigh solution when done boiling. Only water has evaporated, based on laws of mass. No quantum calculations here.
So you can safely subtract 500 grams from 1100 (if you used 600 grams of water) to find your water content and therefore the solution dilution.

Sources: uh...

[LincolnM9]

Do you kow how to make Silica cat litter?

[richardphat]

How would you rate your own experience after using it for a year?

I have not the opportunity to use the glue yet, I just made my own yesterday, and by grinding the sillica gel, it helps because the powder like tends to bind each other and sink in the pot rather than floating.

[rgalka]

What I see commercially available is something like 40% solution... What is concentration of your end product? 100% and if so do I just add water at the end to make a 40% solution?

Thanks

[astrong0]

But! I skimmed the bits off and it made a perfect adhesive! Just barely stuck my front insulation to the inside of the lid. Thanks a lot.

[astrong0]

Bits.

[astrong0]

So.... I've got floating bits in my solution.

[astrong0]

Fantastic information! I recently built a forge and I'm looking for a way to make my sodium silicate. I'm going to use it to glue the insulation to the door.

[rotiron]

What is the shelf life? Do you use it on top of high temp blanket? Does it harden when painted on?

[AndrewW1977]

To be honest I'm not sure of shelf life, I think it would be stable for sometime if you keep it out of moisture. As a refractory you mix it with an perlite, still need to experiment with it to see how well it holds up. It does dry hard but it takes a while.

[RandyG20]

Are you going to use it as a refractory element in a forge? If so, how and why?

[Sir Blah]

I am going to use this in a foundry that I am making as an added layer of insulation between my ceramic fiber blanket and my heat source. I am going to make it into a fire brick by mixing it into sand and perlite. There are several videos around the internet that can help you figure this part out.