Low Fire Clay Ok?

[FloridaSix]

Let me start by saying, I am not a potter although I'm a big ceramics fan. I do own a top and side firing kiln that I've used mostly for glass fusing. I do a lot of glass mosaics and I'd like to make some ceramic pieces to incorporate into my mosaics - basic shapes and maybe work my way up to some decoratively painted fish tiles. All flat. I'd like to purchase some clay and I'm thinking for my purposes, I can get away with low fire. Do you think that's correct? I'm guessing people use high fire for artcles you drink out of or eat off of? Is there a clay 101 on the pros and cons of low versus high fire clay? Thank you!

[Bob Coyle]

If you plan to fire the clay seperate from the glass you should be able to do this. Firing glass on clay usually results in the glass cracking, no matter what the clay body. If you are going to glaze the clay, you need to get a clay and glaze that work together. So use low  fire glazes and low fire clay or high fire glaze with high fire clay. Since you are using a glass kiln, low fire is probably what you want to use. There are a lot of available cone 05 glazes and clays ( 05 is around 1900F). If you are just going to fire the raw clay to the point where it holds together, then you can probably fire to 1400F and be OK.

[FloridaSix]

Thanks for the response. My plan is to use underglazes. Could you tell me if I need to fire to bisque before I apply the underglaze or can I apply the underglaze directly to the leather hard clay? I'm confused also if I have to fire the clear top glaze separately or if I can just layer. I wish I had a mini-kiln for experiments!

[bciskepottery]

Underglazes can be applied at either the greenware or bisque stage. I prefer greenware as the bisque firing adheres the underglaze to the vessel -- less chance for smudging when glazing and you get the opportunity to do any touch up needed. I apply a clear glaze on the fired bisque -- I dip for glazing. But try different approaches and see what works best for you.

[SleepingBird]

I use low fire earthenware clay for making tiles and jewelry. As long as the tiles are not going to be outside in freezing temperatures or in a spot where they are continuously wet, they should hold up. Low fire clay is still porous when mature and so will still absorb water if not completely covered in glaze, eventually causing the glaze to flake off if it gets wet alot. Even tile that is installed will absorb water from the back if the wallboard gets wet. As far as underglazes go, be sure you choose a brand that can be used at greenware or bisque, depending on which you plan on doing. Amaco Velvets, Spectrum 500 series, and Mayco Underglazes can all be used on greenware or bisque. Mayco Stroke and Coat can be used on bisque or greenware, but acts more like a glaze than an underglaze and will stick to shelves like a glaze. I use underglazes on both greenware and bisque. When using on bisque, I lightly sponge on the first layer of glaze to avoid smearing the underglaze, then I don't have to fire again in between UG and glaze layers. Hope this helps, I'm also new to ceramics and tile making, glad to see another here!