Sculpey III
These clays are available in at least forty different vibrant colors. They are easy to work with and has a matt texture effect once baked. Sculpey III can be easily burn so watch carefully when baking. I used these clay when I want a marble effect on my projects. I usually mixed it with other brand. The softness of sculpey III makes my marble achieve its' design. If you used sculpey III alone it tends to crack when you drill them so it isn't quite good for jewelry making.
Studio by Sculpey
These clay are available in 2.8 oz per pack. I love the colors of studio by sculpey, once baked they retain its' color and even brighter, you may want to add translucent for a mild color effect. It just so sad that these brand is going out of the market (So I heard.). Studio by sculpey has just the right amount of softness and it is easy to work with.
Premo
Premo is one of my favorite. These are great for making canes and delicate projects. It is quite flexible and does not break easily especially if your making projects that has thin areas in the design. Premo has a glossy effect after baking. I used Premo for my jewelry projects.
Fimo Classic
Another favorite of mine is Fimo. Fimo is great for caning and detailed art work. It has a rich vibrant color after baking and is durable and firm. Great for making semiprecious stones like jade and amber by combining small amount of opaque colors with large amount of translucent. The black clay is just superb, it does not stain your hands while you condition it or stain lighter colored clay when you reduce them or cut your canes. Fimo classic is flexible after baking and resists cracking. I definitely recommend Fimo.
Kato
These clay are firmer than fimo. According to experts, these clays are the stronger, flexible and does not change color. It comes in 21 colors so far I have used the translucent clay.
Cernit
Cernit is usually used in doll making for its' porcelain-like effect. It is easy to work with, quite sticky and softens easily. I tried using the gray color and it gives me a dark tone after baking. They are strong and durable great for making projects that requires tension and be handled a lot like necklaces, bangles, buttons and among others.
Super Sculpey
Available only in pinkish tan and is used by most doll makers. Can darken if baked too long. You need to condition the clay properly or else you get uneven blotches, small white bubbles and irregularities after baking.
I tried sculpting a baby sleeping, it looks great before I bake it, then after curing small patches appear on the surface of the clay and it completely ruined my projects.
Well, here are some of the guide to which clay you should use and when to use it. If you want to learn more, I suggest a book entitled "New ways with polymer clay" by Kris Richards, "The complete book of polymer clay" by Lisa Pavelka, and "Making polymer clay Jewellery" By Sue Heaser. They have lots of tips and guidelines in the book.
