Oil based clay is clay mixed with some kind of oil or combinations of oil. It will not dry out, but it will oxidize over time and become difficult to work. Sometimes you can manipulate the consistency of the clay by mixing it with petroleum jelly, but this is hard work. Some oil based clays like plastina contain sulfur and can't be used with silicone molding compounds. Plastina can be sealed with a coating of sealer or shellac but any coating of this type will take away some of the character of the clay. We recommend and use an industrial tooling clay which is easy to work and won't react with silicones. Some oil based clays can be melted and poured into a mold. Preheating oil based clay will soften it and make it easy to work.






