Sand casting question

Christyn Mattson · Post by **Christyn Mattson** » Mon Apr 05, 2004 5:28 pm

Going to try sand casting this week. Somewhere I thought I read you shouldn't use 90 because it may stick. Is this due to the softness of the glass? Thus I shouldn't use 96 either? Is float the only option? If so, where can I get some colored float frit? Thanks!
Christyn

Bert Weiss · Post by **Bert Weiss** » Mon Apr 05, 2004 5:46 pm

Christyn Mattson wrote:Going to try sand casting this week. Somewhere I thought I read you shouldn't use 90 because it may stick. Is this due to the softness of the glass? Thus I shouldn't use 96 either? Is float the only option? If so, where can I get some colored float frit? Thanks!
Christyn

I never tried any of the "soft glasses" so I have no idea. As far as colored float goes, if you like gray or bronze, you are in luck. For colors there is a pale blue and a pale green, not easy to get and not worth the effort anyway. I color my glass with enamels of various sorts.

Make a test and let us know.

charlie holden · Post by **charlie holden** » Tue Apr 06, 2004 1:42 pm

I've sand cast with Bullseye and it does fine soaking at 1500 F for an hour. I'm using a sifting of kaolin as a release on top of the sand. My sand mix is about 50% 120 olivine sand, 30% silica sand, 20% plaster.

ch

Bert Weiss · Post by **Bert Weiss** » Tue Apr 06, 2004 2:39 pm

charlie holden wrote:I've sand cast with Bullseye and it does fine soaking at 1500 F for an hour. I'm using a sifting of kaolin as a release on top of the sand. My sand mix is about 50% 120 olivine sand, 30% silica sand, 20% plaster.

ch

Charlie

I always avoid kaolin after I had scum issues in my reusable powder. I never tried bentonite and I wonder if it is a better alternative.

Meanwhile I got samples of VERY fine and relatively coarse alumina hydrate. It looks awesome. I haven't tried it yet.

elizglass · Post by **elizglass** » Thu Apr 08, 2004 10:13 am

Hi,
I have only done sand casting in molds, with a crucible drip. I'd like to try doing hot pours from the crucible. We had used an acetalyne torch to prep the sand- I am intrigued by the notion that you can sift bentonite or kaolin instead. (I don't have a torch, besides a hand held Mapp).
Can you use spray graphite?
Also, does anyone know if I can buy long tongs for picking up the crucible to pour- or is this something I need to invent?
Thanks,
Liz

Brock · Post by **Brock** » Thu Apr 08, 2004 10:16 am

[quote="elizglass"]Hi,
I have only done sand casting in molds, with a crucible drip. I'd like to try doing hot pours from the crucible. We had used an acetalyne torch to prep the sand- I am intrigued by the notion that you can sift bentonite or kaolin instead. (I don't have a torch, besides a hand held Mapp).
Can you use spray graphite?
Also, does anyone know if I can buy long tongs for picking up the crucible to pour- or is this something I need to invent?
Thanks,
Liz[/quote

Yes, spray graphite works well.

Are we going to need another name for this process?

Everybody else in the glass world considers sand casting a hot pour.

Brock

charlie holden · Post by **charlie holden** » Thu Apr 08, 2004 1:48 pm

Brock wrote:
elizglass wrote:Hi,
I have only done sand casting in molds, with a crucible drip. I'd like to try doing hot pours from the crucible. We had used an acetalyne torch to prep the sand- I am intrigued by the notion that you can sift bentonite or kaolin instead. (I don't have a torch, besides a hand held Mapp).
Can you use spray graphite?
Also, does anyone know if I can buy long tongs for picking up the crucible to pour- or is this something I need to invent?
Thanks,
Liz[/quote

Yes, spray graphite works well.

Are we going to need another name for this process?

Everybody else in the glass world considers sand casting a hot pour.

Brock

Sand bed casting? I think of it as hot casting versus kiln casting. This being a kiln casting forum I'm generally going to assume that's what we're talking about. Damn the torpedos...

Liz, as long as the sand is cold when you pour glass on it, spray graphite or acetylene derived carbon smut will work as a release. But both will burn away in a kiln. So we use refractories instead. At the same time that the sand is hot in a kiln, the glass is cooler than it would be in hot casting. So kaolin or alumina or bentonite might react with the much hotter glass during a pour. I don't know. I do know that bentonite will stick to poured glass.

Boyce Lundstrum has pictures of tongs for crucible casting in his "Fusing Book Three". Not really an off the shelf item.

ch

Tony Smith · Post by **Tony Smith** » Thu Apr 08, 2004 2:10 pm

you can find crucible tongs and hand shanks from places that sell foundry supplies. http://budgetcastingsupply.com/Price_Sheet.html#Tongs

or from McMaster-Carr http://www.mcmaster.com and search under foundry tongs (page 2572)

Tony

Cheryl · Post by **Cheryl** » Tue Apr 13, 2004 5:23 pm

and they're cheaper too

Carol · Post by **Carol** » Tue Apr 13, 2004 6:34 pm

charlie holden wrote:I've sand cast with Bullseye and it does fine soaking at 1500 F for an hour. I'm using a sifting of kaolin as a release on top of the sand. My sand mix is about 50% 120 olivine sand, 30% silica sand, 20% plaster.

ch

Going to be firing both BE and S96 on sand in a couple of days. Anyone tried plaster of paris or BE kiln wash as separator?

Carol

Carol · Post by **Carol** » Tue Apr 13, 2004 6:34 pm

charlie holden wrote:I've sand cast with Bullseye and it does fine soaking at 1500 F for an hour. I'm using a sifting of kaolin as a release on top of the sand. My sand mix is about 50% 120 olivine sand, 30% silica sand, 20% plaster.

ch

Going to be firing both BE and S96 on sand in a couple of days. My sand bed is a mixture of olivine sand and plaster (80/20 I think...Bert???) Anyone tried plaster of paris or BE kiln wash as separator?

Carol

Bert Weiss · Post by **Bert Weiss** » Tue Apr 13, 2004 10:33 pm

Carol wrote:
charlie holden wrote:I've sand cast with Bullseye and it does fine soaking at 1500 F for an hour. I'm using a sifting of kaolin as a release on top of the sand. My sand mix is about 50% 120 olivine sand, 30% silica sand, 20% plaster.

ch
Going to be firing both BE and S96 on sand in a couple of days. My sand bed is a mixture of olivine sand and plaster (80/20 I think...Bert???) Anyone tried plaster of paris or BE kiln wash as separator?

Carol

Carol

Your olivine came premixed with 5% bentonite before we mixed in 20% plaster of paris. I have been working without any added plaster as a seperator with fine results on float.

jerry flanary · Post by **jerry flanary** » Wed Apr 14, 2004 12:35 am

How about we call it just Sand Kilncasting?

Carol · Post by **Carol** » Wed Apr 14, 2004 11:02 am

[quote="Bert Weiss
Your olivine came premixed with 5% bentonite before we mixed in 20% plaster of paris. I have been working without any added plaster as a seperator with fine results on float.[/quote]

Thanks Bert. Couldn't remember if there was any bentonite in there. Am doing tests with BE and S96 today, with and without plaster and KW as separator. Will report back.

Carol

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