I conducted my own non-scientific tests on five different polymer clays commonly used by artisans and crafters. I was curious about sculpting qualities as well as the durability of cured clays. Here are the results I found. These were my own conclusions. You may get different results in your own tests.

I started out with approximately one cubic centimeter of each of five polymer clays: Cernit, Fimo Soft, Premo, SculpeyIII, and Super Sculpey. I did not test any other clays - these were what I had available. For the purposes of this test, I used each manufacturer's equivalent of a light fleshtone, straight from the package without mixing any other colors. They vary in translucency and color - both raw and cured. I began the test by conditioning each cube by hand.

Cernit took the longest to condition. One minute by hand. Once conditioned, it was quite soft and elastic with a slightly clammy surface.

Fimo soft took about 25-30 seconds to condition the same sized test piece. The conditioned clay was somewhat stiff with a greasy feel. It was the least elastic of the clays in the conditioning test.

Premo took about 30 seconds to condition. The conditioned clay had a very smooth and somewhat elastic texture.

Sculpey III conditioned the quickest at less than 15 seconds. Conditioned clay is somewhat
stiff and sticky.

Super Sculpey took nearly 45 seconds to condition. Texture of conditioned clay was creamy smooth and elastic with slight stiffness.

The needle tool test results showed that all clays with the exception of Cernit allowed a needle tool to penetrate cleanly into the clay without altering the surface shape much. Cernit "dimpled" when a needle tool was inserted, resulting in a more rounded edge to the holes - an interesting and possibly beneficial effect for certain styles of sculpting.

The fingerprint and pinch test shows how the clay reacts to pressure. Cernit and Premo both bounced back somewhat when pressed with a fingerprint. The others retained the fingerprint well. Cernit and Premo yielded softer edges when pinched. The other clays held a sharply defined edge when pinched.

Another test I conducted was to see how well two pieces of the same clay adhered to each other and how easily the seam could be blended to become invisible. Sculpey III and Fimo both rated high in this category, due to the "spreadable" surface texture. Cernit did not adhere well to itself and the seams were difficult to blend. Premo and Super Sculpey rated good.

The "noodle test" was hardly scientific, but I wanted to see how each clay would react to rolling and stretching into a long noodle.

Cernit did well in the noodle test, but it's sticky, clammy texture made it stick to the table when rolling. It stretched evenly and very impressively, however. Noodle rating: very good

Fimo Soft held up reasonably well under rolling, but broke when stretched. Noodle rating: good

Premo performed very well in the noodle test, rolling and stretching evenly and very thin without breaking. Noodle rating: very good

Sculpey III did poorly in the Noodle test. Even after re-conditioning for an additional
minute, it rolled out unevenly and broke frequently. Noodle rating: poor

Super Sculpey noodle tested quite well. It rolled out evenly without sticking to the table, and stretched nicely. Noodle rating: excellent

Then I tested durability after curing. Each clay noodle was cured according to manufacturer's directions. After cooling for several hours, the cured noodles were wadded, scrunched, bent, and stretched until they couldn't take any more abuse. Once again, hardly a scientific test, but the results were actually very surprising.

Cernit was the most flexible after curing. It bent and stretched quite a bit without breaking.
Durability rating: very good

Fimo Soft was extremely durable after curing. It was flexible, not breaking when bent, but finally breaking when stretched. Durability rating: excellent

Premo was durable and flexible after curing. It flexed without breaking, and stretched a bit
before breaking. Durability rating: good to very good

Sculpey III was not durable after curing. It was brittle, crumbly, and stiff, and took very little bending to break. Did not stretch at all without breaking. Durability rating: poor

Super Sculpey was somewhat flexible but broke and crumbled when tested with mild abuse. Durability rating: fair to poor

All clays retained very good color, though Premo and Super Sculpey darkened ever so slightly.

This concludes my test. If you have any comments or questions, please write me at: batbrat@mac.com. I would love to hear what other people have found.