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Have any of you used one of Patty Gray's casting dams? Hard to believe you can cast frit or chunks without having to cold work the edges as you do when using steel ring and fiber.

A big trick to lining a dam is to make the inner layer of fiber paper about 1/8" shorter then the thickness of edge of the glass.

If you fill Patty's mold with enough glass to go higher than the mold sides, this will accomplish the same effect.

Thanks Bert. I thought there was something magic about the surface of the mold. Just glass to mold ratio, huh? OK, I'll just use my stainless casting ring and fiber paper as you suggested.

I still use the stainless still ring she gave me at a workshop when it turned out there was not going to be enough kiln space for me to do a raking.

anyone have a link talking about the new dams?

http://www.delphiglass.com/casting-mold ... y-dam-mold

http://harrachglass.blogspot.com/2012/1 ... ation.html

GuyKass wrote:
http://harrachglass.blogspot.com/2012/1 ... ation.html

Where do people pick up these firing schedules? Nothing is right about this, on the way up or down.

Bert Weiss wrote:

GuyKass wrote:
http://harrachglass.blogspot.com/2012/1 ... ation.html

Where do people pick up these firing schedules? Nothing is right about this, on the way up or down.

It's not bad, could use some tweaking but it covers all the bases. Bert- this is hobby stuff, not terribly big or thick. I wouldn't recommend it to my students but it's fine.

Marty wrote:

Bert Weiss wrote:

GuyKass wrote:
http://harrachglass.blogspot.com/2012/1 ... ation.html

Where do people pick up these firing schedules? Nothing is right about this, on the way up or down.

It's not bad, could use some tweaking but it covers all the bases. Bert- this is hobby stuff, not terribly big or thick. I wouldn't recommend it to my students but it's fine.

In my view, No bubble squeeze, too fast to top, anneals too hot, not enough time, for 1/2".

I have used the "Patty" molds and I've used stainless rings.

In my experience, the coldworking you are doing with a stainless ring is smoothing out the rough edges as a result of the "graininess" of the fiber paper. I've found that wrapping the edges with a layer or two of Papyros will reduce significantly the coldworking required.

With the dam mold, you spray it with MR97 and then put down a sheet of Thinfire/Papyros. The edges are touching the smooth ceramic BN-coated sides and the bottom is touching the paper. Very little coldworking is required.

I typically use sheet glass or larger glass pieces -- not frit. If you are using frit, you would treat it similarly to using the Creative Paradise jewelry molds -- mound the frit a little in the middle, so that the outside edges are "lower" than the rest. This would avoid the needles that can occur by the glass sliding down the ceramic mold when leveling out.

2 cents,
Dana W.

For those who have used the Patty Gray molds, do they seem to be the usual bisque of slumping molds or a more complex refractory (such as for example the finer, harder material of the Zircar molds)?

I am not familiar with Zicar, but I assume they are more like slumping molds. They do seem to hold up well in the heat, however.

Dana W.

Dana, your 2 cents were very helpful. Thank you.

http://www.bullseyeglass.com/forum/inde ... f=14&t=161
Here are some Zircar Molds. I LOVE mine and have used them for almost 10 years now. You have to treat them very carefully and prime EVERY Time but if used right , they last a life time. Les