Has anyone used expanded metal to strenghten plaster / silica molds? I have used chicken wire and hardware cloth but was wondering if expanded metal might be good and also reusable? My concern is that the 1/16" steel will heat up and expand and do more harm to the mold than good. The mold is open faced and about 24"X6"X 6" deep. I intend to have the expanded metal about 1" from the surface of the glass in the middle of the mold mass. It seems that there was recently some comments about this subject but I just couldn't find them.
also:
In my first attempst at drip casting I apparently did not soak long enough at 1550 to allow most of the bubbles to raise to the surface. Is there a calculation on how long to soak at full fusing temps based on thickness? or some other criteria?
Thanks, I find this site to be most helpful.
Ted
expanded metal in plaster / silica molds
Moderator: Brad Walker
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Chaeli Sullivan
- Posts: 11
- Joined: Sun Dec 28, 2003 4:25 pm
- Location: Idaho
Ted, I think 1550 is a little too cold for drip casting. The temps I have seen and used most are 1600 to 1650. You might try soaking at 1600 or 1650 for 30 minutes then take a quick peek to see if all the glass has dripped out of the pot and the bubbles have popped. If not soak a little longer then peek again or raise the temp a little.
Chae, the chicken wire is used to reinforce the casting molds and hold them together if they crack from the heat of firing. Hardware cloth is a square mesh, usually 1/2" on a side, wire cloth of a wire heavier than most chicken wire that is welded instead of twisted at the intersections. Chicken wire is made of a thinner wire which is twisted at the intersections and formed into hexagonal shaped cells about 1' to 1 1/2" across.
Best wishes,
Tom in Texas
Chae, the chicken wire is used to reinforce the casting molds and hold them together if they crack from the heat of firing. Hardware cloth is a square mesh, usually 1/2" on a side, wire cloth of a wire heavier than most chicken wire that is welded instead of twisted at the intersections. Chicken wire is made of a thinner wire which is twisted at the intersections and formed into hexagonal shaped cells about 1' to 1 1/2" across.
Best wishes,
Tom in Texas
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Chaeli Sullivan
- Posts: 11
- Joined: Sun Dec 28, 2003 4:25 pm
- Location: Idaho
Metal
I agree with the post about firing higher for longer. When I do things that big I go to 1700 and hold for 2 hours to allow all the glass out of the pot and all the bubbles to melt. Regardless of how you try, there will be surface imperfections but they go away on a second firing with some devit spray.
As to the metal, I never use it. If I've got a big mold where stability is an issue I add 1/3 part talc to the dry ingredients. It makes a mold material that I usually need air powered tools to break apart and I like it a lot more than adding an unknown element.
Good luck,
Jerry
As to the metal, I never use it. If I've got a big mold where stability is an issue I add 1/3 part talc to the dry ingredients. It makes a mold material that I usually need air powered tools to break apart and I like it a lot more than adding an unknown element.
Good luck,
Jerry
Thank you Tom, Greg, and Jerry,
I am using bullseye and I am told by them that full fuse is at 1550. I will however jump the temp up to your recomendations and give that a try.
What about large pate de verre (imagine a 5 sided box 6'X14"x4" high with 3/4" walls) What temp might you fire this one too?
Jerry, I like the talc idea especially since you say it is a harder mold.
Do you always mix your plaster, silica and talc dry? I have been adding equal parts to water and mixing with a good drill and mixer. Any reason not to continue this approach?
Ted
I am using bullseye and I am told by them that full fuse is at 1550. I will however jump the temp up to your recomendations and give that a try.
What about large pate de verre (imagine a 5 sided box 6'X14"x4" high with 3/4" walls) What temp might you fire this one too?
Jerry, I like the talc idea especially since you say it is a harder mold.
Do you always mix your plaster, silica and talc dry? I have been adding equal parts to water and mixing with a good drill and mixer. Any reason not to continue this approach?
Ted
Ted, as I understand the term fusing refers to heating two or more layers of usually flat pieces of compatable glass in contact with each other until they soften and adhere to each other. Fusing can vary from tack fusing where usually smaller glass pieces are heated until they just stick to the base glass and edges just start to round off but stay raised above the base glass to full fusing where the glass surface is completely flat across the top and the edges are fully rounded. For BE glass 1550 F with various hold times should give full fuse results. Casting on the other hand involves heating glass until it is soft enough to flow and move like dripping out of a flowerpot or consolidating pieces of frit into a single solid piece of glass as in pate de verre or frit casting into open face molds.
There is an old thread about anealing a 4" cube at http://www.warmglass.com/cgi-bin/wgarch ... read=84578
Your proposed item is larger yet and would likely require a longer aneal cycle.
Best wishes,
Tom in Texas
There is an old thread about anealing a 4" cube at http://www.warmglass.com/cgi-bin/wgarch ... read=84578
Your proposed item is larger yet and would likely require a longer aneal cycle.
Best wishes,
Tom in Texas