Before doing anything else, you must condition your clay.
Even if sometimes – and especially with some brands of clay like Souffle by Sculpey – the clay seems to be soft enough to be worked with right out of the package, do not skip conditioning. A clay that has not been well conditioned will result in an item that will be prone to cracks and breakage even if baked correctly.
You must either knead your clay with your hands – if you don't have a pasta machine – for about 5 minutes or pass it through the pasta machine at least 10 times even if it's soft. Fold the clay and then pass it through the pasta machine repeatedly, placing the fold between the rollers first. That way you avoid trapping air bubbles in the clay.
For harder clay, how do you know when it's conditioned enough? There are two things to look for, one is an approximate sign of conditioning and the other one is an absolute sign. When you get your clay through the pasta machine, it will have rugged edges. As the clay gets conditioned more and more, the edges become less and less rugged. But there are clays that will have rugged edges no matter how well conditioned they are. The ultimate test is: pass your clay through the pasta machine on the thinnest setting (or flatten it with a roller to about 1 mm thickness) then fold it. Look at the fold, at the edge of the fold. Is it nice and smooth, without any sign of cracks? Your clay is almost conditioned. If there is any crack, even hairline thin, then you must condition your clay some more. The final test to see if your clay is conditioned properly would be to fold it again in two different directions after you've folded it in two. Please scroll at the end of this article for a video that can show you the visual of this test.
Contrary to internet rumors, polymer clay does not have a shelf-life. That is, it doesn't “get old” - if it is stored at the correct temperature, that is, below 85F – above that, partial baking might happen and your clay is ruined – that is why it is not recommended, in summer, if you purchase clay from a craft store, to leave it in the car if you have to stop and buy something else, the temperature in the car raises to sufficient levels to bake the polymer clay .
There have been many reported cases of packages of polymer clay found forgotten in the back of a drawer for even 15 years and “brought back to life”.
But as it sits in the storage space, it will become hard. Sometimes, so hard that it needs to be broken with a hammer.
So how do you condition polymer clay that has become rock hard?
Well, you can spend a bunch of money and buy the “no-knead” machine.
Or, you can do like me – I have personally conditioned polymer clay that was 10+ years old. I have a grater and a small food processor specially for polymer clay. I grate the polymer clay then put it in the food processor with a few drops of clay softener. A few pulses is all it takes. I dump then the food processor on my working tile and first knead it for a few minutes by hand, then use the roller to flatten it enough that it would go through the pasta machine on thickest setting. From there it's a child's play. As a piece of advice, do not place too much hard polymer clay in the food processor, even if it's grated. About a fistful at a time is a good quantity.
There are many on the internet who advise you to use baby oil or even vaseline to soften clay. I personally find that both give an awkward texture to the clay and even if you “leech” it you cannot obtain a fine detail retention and smooth finish anymore. So my advice is, always use just clay softener. Also quite important - except for cases of extreme emergency - is to use the clay softener of the brand of clay you are using. If some clay softeners work great on other brands (for example Sculpey clay softener works great for softening Fimo) some brands of polymer clay really require that specific brand's clay softener to keep their texture, quality and color unchanged. One of the polymer clays that I would recommend to always use the brand's clay softener is Pardo - especially because Pardo has a very different formulation than other brands, and also is a little bit different to condition. I will make soon a tutorial about that.
Now, what if the clay is too soft? Sometimes it is too soft in the package, or you might drop a few too many drops of softener in it. Nothing simpler than “leeching” it. Get it rolled in a sheet and place it between paper towels with a book on top for anywhere between half an hour to even 24 hours – depending how soft it is. The extra oils will “leech” out of the clay and be absorbed by the paper towels and your clay will be ready to be used.
How do you know if your clay is conditioned properly or not? Watch this video for information.
