Molding clay – Van Aken’s Klean Klay Alternative, also known as Protolina, is designed to address the needs of sculptors who are, quite literally, looking for an alternative to Klean Klay. Van Aken’s Klean Klay Alternative is an oil based, sulfur free modeling clay that’s been specifically formulated to emulate the properties of Klean Klay. With it’s 99% accurate formula, Protolina can be used for all of the things you used to use Klean Klay for: molds and shims, metal casting, cement casting, and typical fine art uses like sculpting and modeling. Protolina is odorless, non hardening, non drying, and won’t inhibit the curing of silicone. Van Aken’s Klean Klay Alternative cuts the same, models the same, and even melts the same as Klean Klay used to. Sulfur free Non drying Non hardening Oil based clay.