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vwcamper74
2nd Feb 2018, 08:27 AM
Hi everyone,

I'm after some Sodium Silicate to make sand cores but I am trying to find somewhere I can get some from.
An earlier post mentioned that the sodium silicate from a pottery supplier does not work as well as proper Sodium Silicate for casting. Has anyone had experience with this and could someone let me know where I could get hold of some?

Thank you

Mark

XJ9OX
2nd Feb 2018, 12:14 PM
You can make your own sodium silicate fairly easily. Google DIY sodium silicate and you will find a few recipes and youtube videos etc.
You need the following (to make around 600ml):

water - 500ml
(preferably de-mineralised)

Sodium hydroxide/caustic soda - 200g
(drain cleaner available from your local supermarket, but not the stuff with the aluminium chips in it to make it fizz in your drain)

Silica gel - 300g
(can be found in silica gel cat litter, don't worry about the lairy colours, or those sachets of desiccant that come with electrical appliances and some food etc, if you have enough of them.... note: Damprid contains calcium chloride = not the right stuff)

Get yourself a suitable stainless steel or pyrex saucepan (DO NOT use aluminium or you will have a reaction that you cannot contain between the caustic soda and the Al). Add the water then slowly add the sodium hydroxide while wearing safety glasses gloves etc - any misplaced splashes will burn your skin/eyes/throat/clothes/cat. The solution will heat up to "far too hot to touch" as you add the sodium hydroxide and once it has all dissolved, you can put it on the stove to simmer it while you slowly add the silica gel. If the silica does not dissolve completely, you can add a small amount of water until it does or fish the lumps out. This wont affect anything. You will now have fairly concentrated sodium silicate to store for later use. Dilute as required.

I hope this helps.
Simon

GuzziJohn
2nd Feb 2018, 06:10 PM
Hi Mark,
It's been a few years since I was in a similar situation, looking for suitable sodium silicate. I must have been less than impressed with the pottery grade stuff because I ended up ordering a 20l drum from Cast Metal Services in Brisbane.
The stuff was called "Sodasil G". Cost was about $70 plus freight. (4 years ago).

I would contact some foundry suppliers in your state and simply ask if they will supply you something similar.

I was really impressed with how well this product worked. Mixed with clean beach sand. Gassed with CO2 for a few seconds and it was like sandstone.

John

NedsHead
2nd Feb 2018, 07:08 PM
Get yourself a suitable stainless steel or pyrex saucepan

I wouldn't use Pyrex, hot sodium hydroxide will eat right through it in no time.

I make my own sodium silicate in a stainless steel pot using the described method, it's easy and cheap, I like to boil it down until its thick like honey and dilute with water as needed.

vwcamper74
2nd Feb 2018, 11:11 PM
Thank you Simon, John and Nedshead. I appreciate all of your advice.
I will have a go at making some of my own and test it out. Hopefully it will work well. Otherwise I will try to source some Sodasil G or an equivalent.

Thanks again

Mark

XJ9OX
3rd Feb 2018, 04:18 PM
NedsHead, you are right of course about using pyrex. There is a real danger that pyrex can become etched by the sodium hydroxide and fail, sometimes in a very explosive way. I have seen this happen under different circumstances (with a roast meal) and the result was a big mess of broken, very sharp pieces of pyrex and hot fat. The more I think about it, I don't know why I even added pyrex as an alternative. I have always used stainless steel pans to heat the sodium hydroxide solution and I have only ever used pyrex stuff to measure the ingredients.

Much safer NOT to use pyrex equipment for cooking sodium silicate. As I haven't made many/enough posts, I cannot edit my original instructions to delete "pyrex", so perhaps a moderator can fix my error.

Simon

pedropablo
17th May 2018, 07:07 AM
Hi Mark,

the sodium silicate from pottery suplier canīt work.. becouse it is pure silicate. you nee to add a colapsibility property to bring this silicate to a "proper silicate".

add 3.5% wather and 13% sugar at the pottery silcate and it will be same as foundry silicate solution.

first dilute the suggar in hot water and then add the solution to the silicate mix it and let it coold..

Regards