Source of Bentonite?

Home enthusiasts discuss their Foundry & Casting work.

Moderator: Harold_V

4catmom

Post by 4catmom »

Actually, I prefer the oil sand too. Would you share your recipe for the hardware store-bought mix? Last time I bought 100 lbs of mail-order petrobond sand it was over a hundred bucks, ouch! :shock:
Bill Shields

Betonite

Post by Bill Shields »

Having worked in the Saudi Oil industry for a decade, we used to walk around in the stuff by the ton around the wells....Harold is correct regarding its use.

Anyone in the drilling industry knows what the stuff is...they use it to make up 'mud' to keep the pressure on the well up so that things won't 'blow out'....

http://www.wyoben.com/

I see that they are now selling the stuff for 'medical' purposes...yech! No way I would put that stuff IN my body....
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steamin10
Posts: 6712
Joined: Sun Jun 08, 2003 11:52 pm
Location: NW Indiana. Close to Lake Michigan S. tip

Post by steamin10 »

Oil sand is about the oil based binder, and the oxide that will keep brass and bronze from wicking into the sand itself.
The red Iron oxide powder is from the foundry supply again, I forget the trade name, I have some still in a bucket in powder form. It is not important if you are doing aluminum. It is used at a rate of about 10 % with sharp washed bank sand. I used bagged white pool filter sand, which is between 80 and 100 mesh. Dont use torpedo or round river washed sand as the binder will not lock the grains for a stable mold.

Rmemeber to use the hand squeeze test to compare sample sand at any point and learn to see and feel the diferences. It should be a good forming bond without leaving a lot of binder on your fingers. ( What gets left tho is kinda sticky and troublesome to wash off being resistant to soap . Its synthetic. )

The Oil binder is really simple, and mis-named. Buy a Quart of full Synthetic motor oil of 30 or 50 weight. Mix this intoabout 40 - 50 lbs of sand until well coated. Add about 3 oz of Isopropyll alchahol and remix. you will find as you mix the sand it will get stiffer and go to sticking the grains to whatever is mixing it. Continue until it is all kneeded and commit to a covered container, and use the next day. The Alchalhol will act chemically on the synthetic oil and make it sticky. It will NOT work with regular motor oil, or an oil blend. Dont make the sand too wet, if it is, add dry and sprinkle over the mix, and shovel and foot stamp in to kneed the sand. This stuff will stick up my mull when mixing new sand, and jamms the machine it gets so hard to turn at first. A little use will relax the bond somewhat as it evens out, and small amounts of oil or an oz of Alc will restore a tired bond after many many molds. The alchahol will bond with the oil and not evaporate to the air, only under heat of the pour at the burnout line. The heat for pouring will fracture the sand and break it down to the point that it will powder, and the sand will blacken. What will have to be watched it the pourosity of the sand so that it dosn't get too wet, or fine to breathe. Small foundies usually change sand after so many cycles for control, rather than guessing and missing and losing too many parts. If you wnat to run brass and bronze, ther is a red clay iron oxide mix taht is added, Petro bond is one trade name, but it is razzmatazz for the oxide that keeps a barrier from scabbing the sand.

Take care of your sand and store in a bucket(s) or covered recycle tote, avoid carboard and wood that will wick the good stuff away and dry your expensive an prized sand. I work my sand on a steel sheet now, as it darkens concrete, and oils it too. I use a 4x4 sheet of 10 guage, it gets enough oil it doesnt rust much, and the oxide doesnt hurt the sand anyway.

I have a Mighty mite that is a toy really, for a mull , but on 6x6 molds and small work it is the pip! For lots of sand I use the flat shovel and foot work. Flip- stomp across twice- flip- and stomp twice again. Err, dont walk in the house without changing shoes. Carpets will clean them for you. yecchh! I have heavy work boots that I use while pouring and working, in case of runnout or splash. Plastic based joggers or tennies dont getit. Once again, caution is no accident. Burns are no fun, and Emergency care sux on weekends.

Just a note of brag, I have molds, cope and drag boxes, from 6x6 to 15x23, 22 in number. So I can run many sizes of work, and three furnaces to feed them. Never fired more than one yet, have many items not yet in service, like an air hoist for quick raising and pouring of a heavy vessel. Have the ceiling beam in that shop. 24x26 garage, alljammed up with projects tools and findings. Never enough time. Current projest; 21 foot cuddy cabin boat to go wreck diving from with my son.
Ok, gonna end this windy thing, got to mow and acre of grass yet.
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