Just another small bit of information for the green sand casting hive mind: I rang a few agricultural supply companies yesterday to see if they might have powdered bentonite. I understand you can use it to help prevent leaks in dams and soil ponds. Asking for "bentonite clay" tended to confuse people and I soon learned to ask for bentonite and found at least three sources all an hour to an hour and a half drive away. As a last ditch effort I rang a stock/farm supply company half an hour away and asked about some bentonite clay: "We've got no clay listed on the computer"..."What about bentonite?": "No we don't have that", "Can you take a look on the computer?" I asked, "OK, how do you spell bentonite?". I spell it out for him and he replies "No we don't have any of that, we do have something called sodium bentonite, it's $12.50 for a 25 kilo sack". So an hour later, I'm home and I have two sacks in the back of the ute. It's apparently used as a supplement in animal feed, it's not a milled powder but it is much finer than kitty litter. With a bit of use and some mulling I think it would break down into powder and certainly with a bit of water it readily forms a lump free slurry. https://www.jnjresources.com.au/downloads/JNJ RESOURCES SODIUM BENTONITE.pdf
I bought a sack at the local Feed & Seed farm store too. I originally was asking for pond liner but got the feed supplement. A little research showed it is used to help the digestive tract in dairy cattle to improve milk production.
I wonder if the pond liner is finely powdered compared to stock feed bentonite. On a related note I found mention of a "swell test" to distinguish between sodium and calcium (doesn't swell) bentonite. https://globalsynthetics.com.au/wp-content/uploads/2016/05/TECHNICAL-NOTE-SWELL-INDEX.pdf
I bought a bag of finely powdered sodium bentonite, "quik-gel" is the brand. The same business that carries it (Can-Pipe, in Ottawa ON) sells a version of it meant for sealing ponds, but that was more like cat litter consistency. Jeff
So that would be for drilling mud if it was sold by a pipe company?. I guess it would have to be fine powder for that application. Edit: I meant: So they would also have bentonite for drilling mud as a fine powder?.
Mark, I think Bentonite clay is “ by definition” composed of extremely finely ground material. When mined deposits that have dried into a solid hard form are dug up. But, as soon as it is exposed to water it quickly softens and becomes slimy goo. That’s good for us, since I think it will disperse into clay even if dumped into a muller as granules. Wiki:”The montmorillonite making up bentonite is an aluminium phyllosilicate mineral, which takes the form of microscopic platy grains. These give the clay a very large total surface area, making bentonite a valuable adsorbent. The plates also adhere to each other when wet. This gives the clay a cohesiveness that makes it useful as a binder and as an additive to improve the plasticity of kaolinite clay used for pottery.[6]” So, if I had some granular Bentonite to be added to green sand, I probably just add my water to a corresponding amount of Bentonite and expect it to quickly soften and the add that mix to the sand. Once that worked fine, I’d also try just tossing the dry granular stuff into the sand/water mix and see if it disperses. I strongly suspect it would. Denis
That's what I'm hoping will happen with use, it's needing a little mechanical assistance while wet to break up. I'm not using a muller at the moment so it'll eventually disperse with a bit of use, although a fine powdered product would have been ideal. Locating some kind commonly available powdered bentonite would be ideal and the stock feed version goes pretty close.
