Mid Fire Porcelain Clay for slab on mold iridescent glaze
Posted 19 February 2012 - 09:03 PM
I am wondering about the cone 5 porcelain, for pressing slab on big mold to be expose outside after firing (no frizzing environment)
I like it (in theory) because of the low porosity and low cone firing but couldn't find the lows...
it is very different from the porcelain cone 10, strength and work-ability? do you have some experience using it? what are the contras?
why would you advice me to don't use it?
also, I would like to use some very shinny iridescent glaze, white or transparent background (or something else) to bake no more than cone 6, also strong enough to deal with outside, can you tell me about this? or I am asking too much, from materials and you guys!?
Posted 20 February 2012 - 05:20 AM
Posted 20 February 2012 - 02:38 PM
the form will be post on a roof, i would prefer to do the sculpture and carve inside to empty it,
but I want to be sure is the same thickness all around, so planned to cast and use the mold for slab...
seems slower and more work but more secure too...am I wrong?
what max-minimum slab thickness do you recommend?
does this low temp porcelain crack-warping in the cooking as the cone 10?
Posted 20 February 2012 - 05:22 PM
I can’t really tell you how thick the walls should be without knowing what you are doing and how big you are doing it. Rule of thumb for stability, 'the larger the work the thicker the construction'.
If you have never used low fire porcelain before I suggest trying it out. Sculpt some small objects, sculpt some large objects, apply additions and see what you get; make some thick and make some thin walled pieces. Do a smaller model of your design and study it before and after firing. You will then have a better understanding of the clay body that you will be using for your larger work.
Finally, I hope you will be using a mortar to attach the finished piece to the roof. I don’t know where you are planning to install the work, but be mindful of the heavy winds we encounter all around the world.
I hope this helps.
Posted 20 February 2012 - 05:41 PM
Posted 21 February 2012 - 09:23 PM
I thought about porcelain because of the low porosity for the outdoors, and I would prefer to be cooking at medium cone
I admit I am very intimidated by porcelain, in my experience (very limited!) mostly everything cracked or had fissure just at cone 04! which I don't get with my regular clay...
I plan to put the form (24"x 30") with metal structure (1/2"rods) bolted from inside (ceramic with weight on top of metal and epoxied) and extended/bolted to the roof (and pray!)