How does one soften polymer clay? If you are like me, your precious clay would have been hoarded in safe places. And in revenge, they have hardened on you. So now we need to find a way to recondition polymer clay for use. Don’t throw them away!

just want to get started with my clay immediately so this research piece is presented in brief notes to get you going asap.
Various Ways to Condition or Soften Polymer Clay
I will include a useful video to each method where possible. I always find notes are easier and faster when one is just doing a quick refresh. Videos are great for fuller details especially when one has not encountered this information before.
Oil or Water for Re-Conditioning Polymer Clay
This is probably my preferred method as it is so easy and does not need fancy tools or conditioners.
Whether you use oil and the like or water, will depend on the polymer clay you have. Specifically as to whether they are oil based or not.
Sculpey – is oil based clay. So you can use Sculpey Clay Conditioner, oils (baby oil, olive oil, vegetable oil, mineral oil) to soften polymer clay.
Addendum: This addendum is thanks to Agnese, our policrafter reader. She recommends Johnson Baby Oil for softening clay because that oil is full of paraffin. Thanks Agnese!
Fimo – is mineral based clay. For this brand (woohoo!) .. you can use water.
Cut up, crumble or break down the hardened polymer clay into small pieces. Put into zip lock bag or use cling wrap. (It can get messy and stain hands and clothes). Put a few drops of oil/water to the clay. If using cling wrap, just wrap up. Then start kneading the clay. As it softens, you can take clay out, fold over and over. And keep kneading. Eventually you will end up with workable, soft, pliable polymer clay again.
Pasta Machine to Condition Clay
This is my least favourite way. Mainly because I don’t own one! Also, this only works well when your clay is not so hard and stiffened that it crumbles. If the clay is already at that stage .. well, you can’t run it through a pasta machine roller anymore!
Heat to Soften Polymer Clay
Depending on how hard and crumbly your clay has become, you can use the heat of your hands (or body) to soften the clay. Carry the hardened clay in a zip lock bag in your hands (kneading now and then if you like) or put against a warm part of your body.
I prefer putting the clay on a non-stick paper (taped to table) and use a hair dryer to provide the heat.
Hammer – Beat It!
Cut up and crumble up the hardened clay and enclose in some kind of plastic (like cling wrap). Then use a plastic or rubber head hammer to pound the clay. As it softens, just fold clay over, and continue hammering. Persist in this way till the polymer clay becomes soft and pliable.