Here's a little background before I attempt to answer your questions. My college degree (from umpteen bazillion years ago) was in Fine Arts with an emphasis in ceramics.

Ceramics, stoneware, china, porcelain, terra cotta and clay are all the same thing - with important differences. I know that sounds weird but it's true. The two important differences in this case are TYPE of clay and TEMPERATURE of firing.

Clay is essentially a type of dirt taken from the ground and shaped in various ways to make functional objects. The purity and type of clay deposits in the earth vary widely geographically. I live near Lake Michigan in Wisconsin which means I sit on a large expanse of clay (horrible for gardening) - it all used to be a lake-bed. But I digress.

Terra cotta is an iron rich, low fire clay body. Iron makes it red and low fire allows it to be VERY pourous - sucks up water like a sponge - great for plants in your terra cotta pots/terrible if you mosaic it and expect it to last. There are higher fire terra cottas such as chimney flues and roof tiles.

Porcelain is the other end which is a very pure white clay body which can be thrown or cast very thinly and fired very high to produce an impervious-to-moisture plate, cup or other functional object. This is what some people call "china." Tends to be very thin and delicate looking. There are even higher fire ceramics that are used in industrial, medical, and dental applications which don't apply here.

Somewhere in between porcelain and terra cotta is "stoneware." It varies widely according to the manufacturer.

So in a nutshell, your stoneware will soak up more moisture than porcelain, but less than terra cotta. That can be overcome by sealing it before grouting and after, and then at least yearly while in use on an object. I would make sure all edges are covered with grout so as not to allow passage of moisture of any kind into the clay body. If you incorporate porcelain and stoneware you'll need to either:
a: embrace the thickness variance or
b: build up your adhesive under the porcelain to match the height of the stoneware.

What has not been addressed here is glass or plaster - neither of which is clay, and are completely different animals.

Whew, I'm wordy today. Back to hiding out from the unseasonal heat here in the upper midwest.

WOW. wench...you're just a wealth of information. I was just going to try to give some information here...and was looking up another post where I mentioned the "water drop test"....then came back here and you had posted the encyclopeia of ceramics, etc......so my pitful little answer seems a little silly now. :)

Lyndalu, please tell me what the water drop test is???
Wench you definately know your stuff!!! I use the GE to even out the thickness' The falling apart thing is what I'm worried about. Thanks.

Hi bright....the "water drop test" :) - Place a drop of water on an exposed edge of the tile or dish, and if the water is absorbed - the item should be used for interior use only (from a mosaic book by Sonia King). This method was easier for me than trying to determine if something was "high-fired" or "low-fired". In one of Sherri Warner Hunter's books - she mentiones touching her tongue to an exposed edge of a plate - and if it sticks - it should be used for interior use only.

The only problem I have ever had with my outside stuff is i did a birdbath for myself with beautiful hand painted china and after 3 yrs in the sun some has faded and what ever is in whats left from birds in the water has faded one part of them too...but heh it's in my garden and still pretty anyway!Beware tho the plates you are holding up may be like some I bought that looked like peacock feathers I loved them but when I cut them it left white edges because the design was somehow put on top????I don't know how to say they did it ..hopefully yours are not like that tho..Annie

Are you saying the ceramic shards fell apart or the shards fell off the surface of what you are mosaicing?

I see you are in North Carolina, do you take your mosaiced work in for the winter? Freezing and thawing is not healthy for mosaics, the shards or grout can have trapped moisture and as that moisture freezes it expands, cracking the material as it is freezing and then when it thaws it turns back into water and flows away taking some of the materials with it(this is how mountains turn into silt).

Now if the shards are merely falling off the surface, what are you using to adhere your shards to the birdbath? What is the birdbath made of? And again do you take the work inside during the winter?

I don't need to worry about what I leave out in the winter since I am in florida my stones are made from what ever plates I happen upon. I'm not picky about the type of plate(terra cotta, earthenware, stoneware, or porcelain) but I am picky about the decoration method used on the plate. As annie stated above she had some problems with painted china and the peacock feather design. This is because the design is not really part of the glazed surface instead it was fired ontop of the glaze using china paints and ceramic decals. There is nothing wrong with china paints or ceramic decals, they are fairly durable when using the dish for its intended use but outside in the sun and underfoot is not good uses for these kind of decorated shards, I would never use them on things going out of doors or on the floor or even on countertops. These decorated shards are better saved for mosaicing frames, boxes, and interior projects that will not get a lot of handling.

I would like to point out that terra cotta can be fired to a temp that it is not so porous but generally isn't as it is more economical to fire it lower. I find terra cotta items from Italy are much less porous than terra cotta objects from mexico or the U.S.

p

wow wench thank you for that insight i will keep it in mind for the future

cool explanation for the differences, there wench!
it's sure handy to have that much to rely on.

reminds me of that commercial, where the ladies are talking about some subject and the one lady explains the details to the rest and one of them says.."boy, you sure know your stuff" and the other one says "I didn't go to medical school for nothing"...lol

now, from the trial and error end of this...I have broken all of those types of dishes..
the first ones were the cheapest ones I could find..the stoneware
it's thick, and porous and tends to chip around the edges. It's usually the ones with the most bold designs, therefore tempting to collect.
then, I graduated to more thin dinner plates...cost was just a bit more, but worth the difference in broken pieces. more even and smooth on the edges.
now, I don't even consider plates, unless they are porcelain, with gold rims..lol

it's thin, breaks nicely, looks more delicate and is just much nicer as a finished piece.

so, the stoneware is now used for picnics or to give away cookies or something that I send home, after a dinner.

those are my lessons in this one area.

Becky .(*_*).

Stoneware should not be that delicate nor all that porous. Stoneware is generally thicker than fine china yes but that is because it is sturdy everyday ware. Granted not all stoneware is cone10 stoneware, cone6 is also considered a stoneware temp but stoneware shards hold up well for me.

Have you guys given ovenware dishes a try? I had to get me a pair of racheting nippers just to get it to break decently without killing my hand, that stuff is very hard.

p

WELL!!! You all are a wealth of info!!! I usually use the porcelain but in this small town it's hard to come by. And every thing comes out with flowers ..shabby chic look. Which I love, but would like to have a little variance too. My oldest dd wants a foot stepping stone with purple as the main color..and I'm having ALOT of trouble with this one. No purple dishes anywhere.
Pea what is ovenware???

ovenware are dishes that are made to be in the oven, they can take the repeated shock of the heat of the oven to the cool of the table. They are very dense. The clay contains less quartz than say a regular stoneware claybody. The plates generally say ovenware on the back.

I got a large set, did not realize they were ovenware and went to nip one for a stepping stone, hurt my hand trying to split the plate, then the split wasn't where I wanted it as the tool slipped and the break went sideways instead of across the middle. Some of my students were using a racheting nipper that seemed to make nipping easier for them(tho not as accurate), I tried someones nips and it made quick work of the ovenware so I went out and got a pair.

p