KELLY: If you've never seen Laurie Mika's website and are interested in Poly clay, you're in for a treat. ROSIE and I took her workshop in Dallas last year, and it was wonderful. We had already been working in clay, but it was good to get Laurie's tips. Take a look at her icons at:
Mika Arts

K: Read the thread on page 2 "where do you stand on". It relates to your current question.

Of all the polymer clays available, Sculpey is probably the weakest and definitely won't hold up to outside use. Take a look at the website www.glassattic.com and search for strength comparisons of various brands of polymer clays. I doubt that any of them are recommended for outside use. It is a wonderful and versatile medium but does have some limitations. There are two books on Polymer Clay Mosaics and your library can probably borrow them if they don't have them on their own shelves. I think that is the actual title of both of them. Generally "grout" means something a bit different when used with polymer clay, and may mean liquid polymer clay or regular polymer clay pushed in between the tiles. There is a world of information on the internet regarding the use of polymer clay and time spent reading will be very educational.
Regards,
spiderwoman

Sculpey is a swell product but not really designed for outdoor use. You can make neat little objects to hang protected on a porch, as freezing temps won't hurt it, but if it's out in the weather, it can crack and burst if water gets down into any cracks or crevices. Also, even though it's cured in a home oven at 275 degrees, if it gets hot enough, (for example, something left hanging in full sun or in a closed up car) it will get soft enough to scratch, bend and break.

If you do want to try your hand at sculpting for outdoor use, I'd recommend Sculpey II, which is a buff colored clay that when cured makes a more durable final product. It's also handy to add details to existing items like flowerpots and tiles. You can use super glue or E6000 to permanently attach them. Not sure how it would do at grouting, but if you're going to paint it be use to use water based acrylics, and then something like water based ZAR varnish/poly.

That said, even if you can't use it like a tile on a mosaic, it's a terrific medium to design/create an original with, and then make a mold to be poured in ceramic, plaster or mortar mix later.

WOWSERS!! For a Saturday, you guys are a wealth of information! I kinda figured about the outside thing, but good to know that something made with Sculpey COULD go on a screened in porch. Also, that I could make a mold with Sculpey a pour in plaster. (Head. Hurting. Ideas. Swirling.) I go back to school in a couple weeks, my school librarian can borrow those books, also!! Thank you littledog and spiderwoman! And thanks for the website slow and rosemarythyme! Seriously, everything was so helpful!