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Sand Mold Basics

Use this forum for discussion on kiln casting, pate de verre, and related topics.

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Petra Kaiser
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Location: Cape Coral, FL
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Re: Sand Mold Basics

Postby Petra Kaiser » Fri Jan 25, 2013 6:56 pm

I use the dust/powder (trash) from Kaiser Lee Board. It is fine, does not heat up and does not stick to the glass. Does not leave any gum and takes on any impression you want.
petra kaiser, florida,

"Have no fear of perfection, you'll never reach it" -Salvador Dali-

specialized in kiln forming with Kaiser Lee Board since 1998
http://www.kaiserlee.com

Janet McFadyen
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Location: Vancouver Island, BC

Re: Sand Mold Basics

Postby Janet McFadyen » Thu Feb 07, 2013 12:16 am

great info Les thank you I copied and I am going to send myself an email... to have your techinique at the ready. Janet
facebook artist page @ Janet McFadyen's Glass

JanicePeacock
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Joined: Thu May 02, 2013 12:01 pm

Re: Sand Mold Basics

Postby JanicePeacock » Thu May 02, 2013 12:53 pm

I'm joining this thread kind of late but I have a question and I'm hoping one of you might know the answer. I have been told by multiple knowledge glass casters (Norman Courtney is one - he works Bertil Vallien quite often and was my teacher at Pilchuck) that I need a mix of 120 and 180 Olivine for hot glass sand casting (ladle casting). With olivine not really an option, I've been looking into getting Green Diamond which has been discuss in this thread as a replacement for Olivine.

The issue that I am coming up against is that the Green Diamond has mesh sizes of 30/60, all the way down to 16. First, I don't know if mesh sizes and grit sizes are the same - are they? I want to make sure I'm comparing apples to apples on the particle size. Is Green Diamond 30 going to be much courser than Olivine 120/180?

Does anyone have experience working with Green Diamond? If so, what grit/mesh do you use and do have any thoughts about the level of detail that you get?

I don't really want to buy a bunch of sand only to find it is the wrong stuff.

thanks for any help!

Janice

Morganica
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Re: Sand Mold Basics

Postby Morganica » Thu May 02, 2013 2:31 pm

The Green Diamond people are in Oregon, and the one time I spoke with them they were very nice. I'd call them, tell them what you want to do, and let them recommend a mix. (And then please tell us what they said!)
Cynthia Morgan
Marketeer, Webbist, Glassist
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"I wrote, therefore I was." (me)

tbach
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Joined: Tue Jan 04, 2011 11:35 pm
Location: Hillsboro, Oregon

Re: Sand Mold Basics

Postby tbach » Thu May 02, 2013 6:20 pm

There is a new lesson just posted in the past couple of weeks on Bullseye site - for those who have subscription for tutorials - around $40 per year. It is a step by step video for kilncasting with 9mm prefired glass blank. Kind of interesting. Covers the process very well. Gave me the push to find sand (Green Diamond . . . olivine is very difficult to locate - even in Portland, OR) and make plans to construct my box out of vermiculite. Just another diversion, unfortunately . . . my glass education experience is never lineal - always seeing something out of the corner of my eye that I just have to try! For those in Portland area, I was able to locate Green Diamond sand at La Grande . . . at their warehouse in the South Waterfront area near the bottom of the OHSU tram. Really hard to drive in and out of there, FYI, even with mapquest, but they are very helpful. Just google La Grande Industrial Supply - Portland.

Bert Weiss
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Re: Sand Mold Basics

Postby Bert Weiss » Fri May 03, 2013 9:44 am

I first learned hotglass sand casting from Bertil and Paul Marioni. Their process is quite different from ours, because they use carbon for a separator. In a kiln, the carbon will burn up before the glass hits the sand. They also use bentonite and water, which behave quite differently when heated quickly with molten glass, than they would in a slow, hot, kiln heatup. Many years later, I was taught how to kilncast with sand. That lesson used 20% dry plaster mixed with the sand. I have switched to 25% alumina hydrate, because it lasts longer for me. I reuse my sand mixes over and over. I have experimented with many different sands over the years. Most I have tried work. The big deal is particle sizes. For the strongest mold, you need a range of particle sizes from coarse to fine. This will create the strongest matrix. If you only use finer particles, the weight of the glass will smush it down more, changing the pattern.

I have yet to try greensand, but I have a small sample to experiment with. I recently inquired about the green sand, and it does come in a range of particle sizes.
Bert

Bert Weiss Art Glass*
http://www.customartglass.com
Furniture Lighting Sculpture Tableware
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Laurie Spray
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Re: Sand Mold Basics

Postby Laurie Spray » Wed May 08, 2013 8:52 pm

Wow.....i bought a 5 lbs of olivine that I have never opened!! You all have inspired to test it this week! thanks! =D>
Laurie Spray

New website!! Http://bonnydoonfusedglasstools.com
Maker of stainless steel rings,pattern bar formers, pot melt pots, and Bottomless Molds
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Mike Jordan
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Re: Sand Mold Basics

Postby Mike Jordan » Thu May 09, 2013 7:34 pm

I have two 100 pound bags (minus some I took out of each to put in a bucket that is still in it) of Olivine sand 80 and 120 grit I think, and a 50 pound bag of Bentonite that I bought several years ago from La Grande. I had planned on doing some sand casting but never got around to it. I've been planning to make a dry bird bath for the birds with it, but haven't decided where to put it. This stuff is sure fine sized sand and doesn't act like play sand or beach sand at all. I spilled some at the curb when I pulled it out of my car and it took forever for it to wash away. Tbatch is right about finding the place if you don't know the area. Luckily I use to work about 2 blocks from where their warehouse is located and use to go to the Old Spaghetti Factory all the time so I had a good idea where it was.

Mike
It's said that inside each of us is an artist trying to get out. Well mine got out... and I haven't seen him since.

Buttercup
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Joined: Mon Jan 28, 2008 5:22 pm
Location: S.E. Queensland Australia

Re: Sand Mold Basics

Postby Buttercup » Wed May 15, 2013 11:11 pm

Apparently Olivine sand has disappeared in Oz, too. I found that out some time ago but just recently, looking for a substitute, contacted a foundry supplier who said that Olivine flour is still available.

He suggested ILMENITE or CHROMITE or a product called RIMS, all of which are available here. Rims is apparently Ilmenite mixed with another component which assists in achieving a silky smooth finish on foundry castings, but he has no experience with glass applications. All are stable at the temps. necessary for simple kiln carving. (I use 'simple' in the 'uncomplicated' sense, to differentiate from the many-step process of hot glass casting.)

I looked here on the WGB and also consulted the big encyclopedia in the sky and re-read the info in Rick's book, but there were no clear answers to my questions.

From postings by knowledgeable board members I understand that a mixture of grit sizes will give a more satisfactory result. (120 and 80?)

1. Does anyone have experience with ILMENITE, CHROMITE or RIMS, please?
2. Would there be any point incorporating Olivine flour into the matrix or sifting it onto the surface?
3. Would Bert's 25% alumina hydrate & 75 % chosen product be the way to go with these products, too? ( I have alumina).

I know I could experiment but since I don't need a semi-trailer load the rep. is going to source a small amount from one of his customers. I'd like to be specific if I could. I'd really appreciate any input anyone can offer. Jen

jcrowe
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Re: Sand Mold Basics

Postby jcrowe » Thu May 16, 2013 7:21 am


Bert Weiss
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Re: Sand Mold Basics

Postby Bert Weiss » Thu May 16, 2013 7:50 am

Bcup, sands stick to glass, so the alumina or plaster powders are in the mix to coat the sands so they don't stick. Powdered olivine sounds to me like a negative for this reason. You want the nonsticking powder on the outside of the matrix.

I found that most of the sands I tested worked. You want a matrix of different particle sizes for increased dry strength.
Bert



Bert Weiss Art Glass*

http://www.customartglass.com

Furniture Lighting Sculpture Tableware

Architectural Commissions

Buttercup
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Joined: Mon Jan 28, 2008 5:22 pm
Location: S.E. Queensland Australia

Re: Sand Mold Basics

Postby Buttercup » Thu May 16, 2013 6:40 pm

jcrowe, thanks for the MSDS. The product Green Diamond is not available in Australia so I didn't mention that in my query, but thank you for the MSDS. It will be useful to compare its components with the other products that are available here.

Bert, thank you for that clarification. I'll get back to the rep and see which of the other three he has ready access to, (not olivine).

Thanks to you both for the input, Jen


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