Results 1 to 6 of 6

Thread: Sodium Silicate

  1. #1
    Join Date
    Nov 2012
    Location
    Mildura
    Posts
    7

    Default Sodium Silicate

    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

  2. #2
    Join Date
    Feb 2009
    Location
    Tasmania
    Posts
    3

    Default

    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

  3. #3
    Join Date
    Nov 2007
    Location
    Rockhampton
    Posts
    161

    Default

    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

  4. #4
    Join Date
    Jan 2016
    Location
    Wodonga Vic
    Age
    32
    Posts
    280

    Default

    Quote Originally Posted by XJ9OX View Post
    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.

  5. #5
    Join Date
    Nov 2012
    Location
    Mildura
    Posts
    7

    Default

    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

  6. #6
    Join Date
    Feb 2009
    Location
    Tasmania
    Posts
    3

    Default

    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

Similar Threads

  1. Sodium Silicate Supplier
    By GuzziJohn in forum THE FOUNDRY
    Replies: 2
    Last Post: 18th Nov 2013, 08:56 PM
  2. Tri-Sodium Phosphate, strip lathe
    By neksmerj in forum METALWORK GENERAL
    Replies: 27
    Last Post: 27th Dec 2007, 07:20 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •