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Kilnforming on a Sand Bed

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Kilnforming on a Sand Bed

Postby Chris_Petrauskas » Tue Apr 16, 2013 10:02 am

Watch the Lesson at:
https://videos.bullseyeglass.com/videos/kilnforming-on-a-sand-bed/

Please discuss and comment in this thread.

Thanks!
Chris Petrauskas
Bullseye Glass Co.
Portland, Oregon, USA
http://www.bullseyeglass.com
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Re: Kilnforming on a Sand Bed

Postby mycrafts » Mon Apr 22, 2013 7:20 pm

Hi

There is no olivine sand available in Australia...we do have lots of beach sand though ;)

Also sandblasting sand, which seems to be of a more even grade than beach sand, assume it has been pre-sifted for this.

Could you advice:

any different techniques that need to be applied if using either of the above?

beyond the silica health hazard, are there any other issues to watch for with above types of sand?

Many thanks, Myvalley
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Re: Kilnforming on a Sand Bed

Postby valerie_adams » Tue Apr 23, 2013 9:18 am

Informative lesson, as always, but the sources for Olivine sand in North America seem tapped.
Do you have a source you can point us to?
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Re: Kilnforming on a Sand Bed

Postby marykaynitchie » Tue Apr 23, 2013 9:29 am

We are currently using Green Diamond AFS 115 sand. To find a source in your area, contact

Bob Anderson
bob@greendiamondsand.com
Tel: (206) 419.1667

Note that huge minimum quantities are required to order directly from Bob. Contact him only to find your local source.

If that seems like a hassle, take comfort in this direct quote from the Research and Education department: "...pretty much any old sand will do. Sand from the beach, sandbox sand, foundry sand. They are all good."

Mary Kay
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Re: Kilnforming on a Sand Bed

Postby mycrafts » Wed Apr 24, 2013 12:53 am

Thanks Mary Kay, that is encouraging ;)

Many thanks, myvalley
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Re: Kilnforming on a Sand Bed

Postby marykaynitchie » Mon Apr 29, 2013 10:13 am

A member sent us a question this morning asking how to make the vermiculite box. Excellent question! While vermiculite can be tooled similarly to wood, there are a few extra steps to take to fabricate a good, kiln-worthy box.

I found the instructions in
TipSheet 5: Bullseye Box Casting. http://www.bullseyeglass.com/methods-id ... sting.html

(I found TipSheet 5: Bullseye Box Casting by visiting the
Methods and Ideas > Index to Articles.)
http://www.bullseyeglass.com/methods-id ... icles.html

Copied nearly verbatim, from the article, for your convenience:

Vermiculite board

Vermiculite has a bad reputation because it is often mined in the same places as asbestos, which can contaminate the vermiculite. Bullseye Vermiculite Board comes from a mine that is certified asbestos free. It is stronger, more durable, and less expensive than most fiberboard and can be cut and tooled like wood or particle board. Work in a well-ventilated area and wear a NIOSH-approved respirator whenever generating dusts. If you want your finished piece to be level and square, it is important to cut the vermiculite boards accurately.

Also, pre-drill and countersink screw holes so the board does not bloat or blow out when you screw it together. Use stainless steel screws to put the mold together as they will hold up to repeated firings without flaking. Do not use galvanized steel screws because upon firing, the galvanization will release toxic fumes and the screws will flake and cause contamination in your kiln.

Cut two long side boards, two short side boards, and one base board. Lay the boards out as an open box and pre-drill holes in the flat surface of the long side boards to connect them to the ends of the short side boards using a bit that has a diameter slightly smaller than the diameter of the stainless steel screws. Be sure to drill your holes on center to avoid blowing out the side of the board. Then screw the sidewalls together.

Next, set the base board on top of the assembled side boards and pre-drill holes to join it to the sides, and then screw it together. Then take the entire box apart and fire the vermiculite board at a rate of 500°F (278°C) per hour to a temperature of 1580°F (860°C) or about 55°F (30°C) higher than the temperature at which you will cast the glass. Hold at that temperature for half an hour, and then crash cool the kiln. Once the boards are cool, take them out and reassemble the sides using the stainless steel screws. Cut a piece of 3 mm fiber paper and set it on the base board, then set the assembled sides on top of the fiber paper, and screw the box together. Line the side walls with 3 mm fiber paper, making sure that it fits tightly, without bowing or leaving gaps in the corners.


Mary Kay
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Re: Kilnforming on a Sand Bed

Postby Stephen Richard » Mon Apr 29, 2013 1:01 pm

To avoid excess separator on my sand, I use an old sock (with no holes!) to dust the separator over the sand. This gives an adequate separation, without over doing the thickness of the separator.
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Re: Kilnforming on a Sand Bed

Postby Stephen Richard » Mon Apr 29, 2013 1:04 pm

Mary Kay,
It should also be noted that cutting vermiculite boards is very hard on tools. Do not use your best tools for this work. It dulls the tools very quickly, although they continue to work for the vermiculite, they will no longer work well on wood. So separate (cheap) tools are best for vermiculite.
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Re: Kilnforming on a Sand Bed

Postby marykaynitchie » Tue Apr 30, 2013 8:45 am

Stephen,

Both of these are sensible suggestions--as always, thank you for contributing!

Mary Kay
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Re: Kilnforming on a Sand Bed

Postby charlie » Tue Apr 30, 2013 8:50 am

Stephen Richard wrote:To avoid excess separator on my sand, I use an old sock (with no holes!) to dust the separator over the sand. This gives an adequate separation, without over doing the thickness of the separator.


ie: using a pounce
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