Sodium Silicate RU

Discussion in 'Sand Casting' started by PROSTOCKTOM, Apr 3, 2019.

  1. PatJ

    PatJ Silver

    When I went to the brick place, I brought a sample jumbo Cretors flywheel and showed it to the guys in the front office.
    The were most impressed at my backyard efforts, and so were very kind.
    Not everywhere is like that, but some places are.

    .
     
  2. PROSTOCKTOM

    PROSTOCKTOM Copper

    Well I finally made it down to my friends foundry today. He gave me a 5-gallon bucket of Hill and Griffith Company, Corosil GU Sodium Silicate. They are based in Cincinnati, but they also have an Indianapolis location, so I called to inquired about the RU formula I was looking for and they told me that their Corosil GU is in fact RU, so that worked out well for me. They have it in stock in Indianapolis and it's no problem for anyone to drop by the Indy store to buy it. A 5-gallon pail weighs 60# and they charge .97 cents per pound for it. I didn't think $58.20 for 5-gallon was a bad price should I need more down the road.

    I also got his core sand recipe he likes to use on baked cores.

    12# of Sand
    3 ounces of Flour - Corn
    1.6 ounces of Vegetable Oil
    1.6 ounces of Water

    Bake them at 275 degrees for 10 minutes per 1/2" of core thickness. He pours about 700 to 1000# of aluminum a week using core made this way, so I know it works.
    He also told me that the core can be made harder or softer by changing the oil ratio. More Oil - Harder Core, Less Oil - Softer Core.

    Now I can start playing around and see what kind of cores I can produce.

    Tom
     
  3. DavidF

    DavidF Administrator Staff Member Banner Member

    That's a really good price. I think a 5 gallon pail is 125.00. Not sure on the weight...
     
  4. Chazza

    Chazza Silver

    Thanks for posting Tom!

    What does the "#" symbol stand for in your post?

    Cheers Charlie
     
  5. PROSTOCKTOM

    PROSTOCKTOM Copper

    # after a number is the symbol for weight in pounds. Seeing your from Australia you probably don't use this symbol down there, but it is very commonly used in America.

    Tom
     
    Last edited: Apr 24, 2019
  6. Chazza

    Chazza Silver

    Thanks Tom!

    I learn something new everyday – we use lb as the symbol for pounds, but only oldies like me know what they are,

    Cheers Charlie
     
  7. :D It was called the "pound sign" before it became a hashtag.
     
  8. PROSTOCKTOM

    PROSTOCKTOM Copper

    Having now made several cores using the RU with sugar added I am quite pleased with the results. However from a cost stand point and easy of grocery store available materials I understand why my friend uses the flour/oil and bakes his cores. Using RU and gassing is all about saving time and I'll probably stay with it since I don't have a dedicated oven for core baking. However I probably need to acquire some type of oven for some of the larger cores I plan to use down the road.

    Tom
     
  9. I tried to use this recipe, and it would not harden at 275 degrees or even 350 degrees. If you use 275C (527F) it works just fine. Since everything was in English units...
     
  10. Melterskelter

    Melterskelter Gold Banner Member

    Good sleuthing, OIF. Sounds like an important consideration.

    Denis
     
  11. Melterskelter

    Melterskelter Gold Banner Member

    Here is a video demonstrating the relative strength of a sodium silicate core I made (and screwed up when attempting to get it out of the box). Still it allows a little destructive testing of the pieces. I am posting this as there has been some recent discussion of poor strength of sodium silicate molds. General clumsiness and not poor strength caused the demise of this core. I have used the same set up at least a half dozen times previously with good results.



    Denis
     
    oldironfarmer likes this.
  12. Great video, but I'm having trouble hearing your numbers. Would you mind putting the material (RU?) and additives in text?

    For my stuff I have good results gluing broken cores back together with common white wood glue, wiping the squeeze out while wet, and I can't see the seam in the casting.:D

    But my stuff is not for sale.:rolleyes:
     
  13. Melterskelter

    Melterskelter Gold Banner Member

    Edited and cleaned up mixing recipe info. The initial note this morning was mixed up —preceded my cup of coffee ;-)

    Recipe Used:
    Sod Silicate RU 100gm
    Water 15gm
    Table Sugar 15gm
    (Propylene carbonate “Chem Bond-210 Catalyst” 10gm if desired)

    Add 5 gm of the above mix to 100gm sand (a 5% mix)

    Then add
    Sea Coal 5gm for a 5% mix of added coal. Sea coal could also be added at the beginning to dry sand for ease of mixing.

    Propylene Carbonate 10gm can be added to the water/sugar/sodium silicate mix shown in the first paragraph if desired to make the core solidify without CO2. You still only add 5gm of the sod silicate/water/sugar/prop carb mix to the sand for an overall 5% mix.

    The above mix can be gassed, baked or allowed to setup if prop carbonate is used. With the propylene carbonate the mix kicks off at room in temp in a "few" hours without using CO2. I have not used it enough to determine how many hours gives what degree of hardness. I do know that overnight at room temp results in a pretty set. The set speed can be accelerated by holding it at 100 or 110 F and probably higher.

    If you do not use the sugar, the core becomes a rock-hard addition to your iron casting that is like concrete. How hard it gets in aluminum or bronze I do not know.

    There are reportedly other additives besides Prop Carb that give faster set times and a member here was going to post info on them, but I have not seen it. May have missed it. (I have seen online references to them but have not found them in less than industrial quantities and have not found specifics on how to use them.)

    Denis
     
    Last edited: May 27, 2019
    oldironfarmer likes this.
  14. PatJ

    PatJ Silver

    Looks like a pretty strong core.

    The SS I have used from Budget Castings (not sure exactly what its composition is) at 3% breaks down relatively easily after a pour, especially if water is added, and that is without any additives.
    Have not tried it with iron yet.
    Using more than 3% will produce the rock hard cores that you mention, and they do not break down easily.
    But 3% works well and has good strength.

    I have not tried my Clay Planet SS with catalyst yet.

    .
     

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