Release agent question

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RONALD
Posts: 668
Joined: Sun Oct 26, 2003 7:27 am

Re: Release agent question

Post by RONALD » Fri Feb 26, 2021 1:08 pm

I have been casting metals, and using the sodium silicate CO2 system since the 1970's.

Made hundreds of pounds of the stuff, I used it for facing, cores, and full molding.

The first thing, is to find a foundry supply company that has the foundry designated S.S., the ADCOSIL I use is no longer available.

The foundry S.S has certain added chemicals that help.

I have three mullers, and the (blue) Lab Muller is the one I use for the S.S.

I weigh out 25lbs of sand add 400ml of ADCOSIL N. S.S. and mull for ~ 5 minutes, I then dump the sand into a plastic bag, in a garbage can, and repeat the process. When I have filled up the bag, if tightly sealed, it will last for many weeks.

Below are some of the castings I made using S.S. sand, as a release agent I mostly use ordinary parting compound.

The biggest castings were the Waterbed castings I made, for each I used a lot of the S.S. sand, for those I used a coating from Foseco, whose name I can't remember.

Here is the reference for info on metals: http://www.hkramer.com/foundry-data-handbook.html

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jscarmozza
Posts: 553
Joined: Mon Mar 03, 2014 5:09 pm

Re: Release agent question

Post by jscarmozza » Fri Feb 26, 2021 6:21 pm

NICE FOUNDRY!
I'm well aware of the benefits of using sodium silicate for cores even though I don't use it that often, but I was not aware of its use for facing. That's a technique that I'm going to have to explore. Do you just put a facing layer of sodium silicate sand mix over the mold, gas it and back it up with green sand; or face it, back it up, then gas it? I'd like to know more about this Ronald. Thanks.
John

RONALD
Posts: 668
Joined: Sun Oct 26, 2003 7:27 am

Re: Release agent question

Post by RONALD » Fri Feb 26, 2021 8:27 pm

I use facing sand made of S.S. treated sand when I consider the type of pattern I'm using.

In the photo bellow, I will come and put a layer of S.S. on top the pattern about one inch thick, harden the sand, and then add Petrobond 2 sand to fill up this drag. Because the S.S. protects the pattern, I can now really pound down the Petrobond.

Once I use the S.S. sand, it is not recoverable, so by using the P.B.sand for most of the cope and drag, I save on sand.

For the cope which consists of runner and a sprue out of styrofoam, there is no need for S.S. sand.

The photo reads 2013, and was poured in A319 a few days later.

I have the same identical items in the same position today, but I have not been able to complete the molding or casting because I'm recovering from some minor problems. I have produced several switches without guard rails, so hopefully, I will pour them this spring.
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jscarmozza
Posts: 553
Joined: Mon Mar 03, 2014 5:09 pm

Re: Release agent question

Post by jscarmozza » Fri Feb 26, 2021 9:00 pm

Thanks for the explanation Ronald, I'm going to try that technique. By the way, you do really nice castings, was this your trade or did you just do it for a hobby?
John

Harold_V
Posts: 19366
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Release agent question

Post by Harold_V » Sat Feb 27, 2021 2:23 am

Ron,
One question about your process. When you shake out, how do you prevent mixing the two sand types?

H
Wise people talk because they have something to say. Fools talk because they have to say something.

RONALD
Posts: 668
Joined: Sun Oct 26, 2003 7:27 am

Re: Release agent question

Post by RONALD » Sat Feb 27, 2021 12:01 pm

If you read back to my posts over many years, you will find that I taught Physics at a technical high school, casting metals has been my hobby since I melted Type Metal over the kitchen stove as a kid.

I was fortunate to be at the school while there were all kinds of shops I could use, including Foundry; I bought what was left of the closed foundry.

Today, at the school, it is just STEM, an elitist program for just a few selected students, not everybody, like it had been.


S.S. teated sand is usually white, and will remain in big chunks after you pour.

Real foundries usually will regrind the stuff to recapture the sand, most hobbyists thro it away.


Burn out is a problem with many kinds of treated sands, especially PetroBond oil treated sand.

In the photo below, I'm cleaning up the sand near the the wall of where the frog casting was.

Notice that the sand has burned. I pour my switch frogs out of C99700 White Tombasil, at around 2300'F.

The oil in the PetroBond bursts into flame when pouring, but quickly extenguishes.

Not wanting to add to much burnt sand back into my PetroBond, I make the on the spot decision how much I will save; can't save it all.

After awhile, if you save too much burnt sand, the PetroBond can turn almost black, and cause mulling problems.

In the photo, my buddy Ean, is holding the still hot #8 frog with the gating still attached, and in the background are several just poured wooden flasks of yet to be opened frog castings.
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jscarmozza
Posts: 553
Joined: Mon Mar 03, 2014 5:09 pm

Re: Release agent question

Post by jscarmozza » Sun Feb 28, 2021 5:10 pm

We cast the wheels today and got 10 out of 12 to come out, you'll notice in the photo that I forgot to vent the mold where the 2 wheels didn't come out. Random metal as usual, started out with two melts of all red brass from a water meter body that I had, the third melt was half red brass and half yellow brass, the forth and fifth melts were whatever was laying around. The red brass poured weird, after melting under a borax cover and skimming the dross we added some phosphor cooper shot and let it soak for about two minutes, the surface was very shinny but it was a crust that the liquid metal had to break through and then poured out from underneath. The half and half was melted without borax, was skimmed, soaked and it poured well. The who knows what brass was melted with borax because it was dirty stuff, skimmed, soaked and poured, it also poured well. The proof will be how well these wheels machine, past experience was the red brass machined well and the yellow brass didn't. I'll keep you posted.
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