Re: bentonite clay
Posted: Sun Nov 10, 2013 3:05 am
Ummmmmm I use green sand only with corn flour 
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bentonite clay
http://founddreaming.com/metal_casting/forum/phpBB3/viewtopic.php?f=28&t=380
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Re: bentonite clay
Posted: Sun Nov 10, 2013 2:51 pm
Yep, 3 to 5% Bentonite per Navy Manual. I reverted to bad info from another source. And clean pit sand, I think Rasper had some problems with sand that had some calcium in it.
Re: bentonite clay
Posted: Sun Nov 10, 2013 7:48 pm
My sand has 10% bentonite 2% corn flour, but next time I make some I'll use Mr Miyagi (Frank) recipe 5% bentonite 5% corn flour and 5% waterJammer wrote:Yep, 3 to 5% Bentonite per Navy Manual. I reverted to bad info from another source. And clean pit sand, I think Rasper had some problems with sand that had some calcium in it.
Re: bentonite clay
Posted: Sun Nov 10, 2013 9:10 pm
You can get away with the 10% bentonite as long as you pour your metal as cool as you can, quick like with some head pressure, so it chills in the riser before it reaches the top of the mold. You'll get a gorgeous cast product that way... smoooooth and without blemish. Pour too hot, though, with that much binder, and your mold will have difficulty absorbing the steam and/or off gassing of the petrobond oil. Casts will end up with porosity throughout the piece as well as on the surface of the cast.
Wax on... wax off, grasshopper!!
Wax on... wax off, grasshopper!!
Re: bentonite clay
Posted: Sun Nov 10, 2013 10:02 pm
Thanks and yes he did answer me..
and i live in PA USA just south of Pitts about an hour an a half im right down the road from Johnston PA where they had many metal foundry's back in the 70s and i think maybe even into the early 80s.. It doesn't take much understanding that beach sand won't work for reasons already said i live only 12 miles from ANH Refractories and IFB INC. witch is great for me and if anyone would be interested in their products i would be happy to help as i know the owner of IFB and hes very nice and easy to deal with also more than happy to deal with us back yard guys he also gets some brick in that doesn't meet their specs and he GIVES it away other wise he has to pay big bucks to have it dumped he has given me many fire facing brick witch are real nice..Anyway the 50/50 mix it will be im going to get it ordered tomorrow from ANH and go pick it up along with another bag of castable as i have found one 55# bag dont go far at all. :/
and i live in PA USA just south of Pitts about an hour an a half im right down the road from Johnston PA where they had many metal foundry's back in the 70s and i think maybe even into the early 80s.. It doesn't take much understanding that beach sand won't work for reasons already said i live only 12 miles from ANH Refractories and IFB INC. witch is great for me and if anyone would be interested in their products i would be happy to help as i know the owner of IFB and hes very nice and easy to deal with also more than happy to deal with us back yard guys he also gets some brick in that doesn't meet their specs and he GIVES it away other wise he has to pay big bucks to have it dumped he has given me many fire facing brick witch are real nice..Anyway the 50/50 mix it will be im going to get it ordered tomorrow from ANH and go pick it up along with another bag of castable as i have found one 55# bag dont go far at all. :/