Welcome to my Flaming Furnace site.

On this site I'll share how I made my foundry with explanations, images, videos and links to other informative sites. I will also share my experiences with sand casting and creating different objects from aluminum alloy.
I welcome anyone to post comments.

Wednesday, November 23, 2011

Green casting sand VS oil bonded sand

I decided after using oil bonded sand (petrobond) to test some homemade green sand. I got some play sand and after doing a bit of Internet research I started making the green sand. My goal was to make it at minimum cost and to achieve semi good casting quality ;-).
I started experimenting with small quantities measuring first 1KG of sifted and dry play sand. I used a mixer to grind the cat litter (clay) to a powder stage and then sifted 100gr (10% of clay), mixing both together and after just adding small amounts of water at a time. The process was very quick and the sand mix was ready after performing the squeeze test.

My first casting was an aluminum eagle. This was the 12th aluminum eagle I have casted and the result was very promising. No difference in the quality of the casting from the oil bonded eagle castings.

I decided to cast a bigger aluminum object this time so I casted my 3rd aluminum sun. The quality of the casting in this case was not the same. The oil bonded sand sun casting was with almost zero defects and the green sand casting was with a lot of defects mostly porosity. Perhaps from not ramming the play sand hard enough or from the lack of vent hole but again it's not the worst sand casting. I hung the sun on a garden wall and the defects aren't even noticeable it just needs a bit of sanding and polishing.

How oil bonded sand VS green sand:
Oil bonded sand produces a better quality casting but is much more expensive then green sand. Green sand is cheap, easy to make and re-usable. Oil bonded sand is stinky, smokey and stains everything it comes in contact with. Green sand is clean with no smell. Oil bonded sand is much more sticky then green sand. Green sand is alot more fragile then oil bonded sand.
If you are looking for amazing finishing on your casting use oil bonded sand. If you want a cheap solution for casting, for example some heavy machinery parts green sand will do just fine.

Here is a 5 min' demo video I made of how to make casting green sand.


  1. so if it sticks to the hand, theres too much water and you need to add more 1:10 cat litter:sand mix. and if it doesnt retain its shape and breaks clean, theres too little water?

    1. Correct, too much water the sand will stick to the hand.I if the sand crumbles, or doesn't retain its shape either not enough water or not enough bentonite clay.
      It will work fine with 10%-12% clay. It's very important to get the correct cat litter and fine sand.

  2. What brand of cat litter do you recommend? Great work by the way :)

  3. Getting the right brand is important. I got a cheap Aldi store brand and ended up having to add 20% clay to 80% sand to get it to clump properly. So it does not seem to have contained bentonite. However it works so I have continued using it for sand casting.

  4. I did the exact same as you and the sand wont even stay in the little wooden rectangle when I try to flip it over, I used beach sand, water and cat litter did the squeeze test it all checked out and it failed What am I doing wrong?

    1. Can you please provide me some more info:
      1.What type of cat litter did you use?
      2. How much water did you add?
      3. Ratio of sand and cat litter?

  5. They look great well done

  6. If it's ok to post this, I have pure bentonite clay for auction on ebay, I'll post the link with approval or you can search for user kendtv. It's a very fine dry powder, pure bentonite, 2 lb bag is $16 with free shipping in USA. Out of a big bag from a pottery studio that closed down. Also have 1/2 lb package.

  7. If you would like some good bentonite let me know I may be able to assist.


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