Cernit Varnish is a water-based sealer for polymer clay, made in Belgium by The Clay and Paint Factory. Being water-based it cleans up with water, has little smell, and is safe over alcohol ink — solvent varnishes and dimensional glazes dissolve alcohol ink and make it run, so this is the type to reach for if you have colored a piece with Cernit Alcohol Ink.

It also means the varnish ships by air, unlike the inks themselves, which are restricted to ground carriers.

On the matte finish: in Ginger Davis Allman’s test of 41 polymer clay sealers, the Cernit matte came out among the successes — a dry-feeling, durable finish across every clay brand she tried, and one of the very few varnishes that stayed scratch-resistant on Kato, which defeats most sealers. Worth setting expectations though: she found it reads closer to a satin than a true dead matte.

Test first, always. Every polymer clay sealer behaves differently on different clay brands, and a varnish that is perfect on one can stay tacky or bead up on another. Bake a scrap of the clay you are working in, varnish that, and leave it a few days before committing a finished piece.

Supplied as a 250ml bottle — the working size, at a lower cost per ml.

Ginger Davis Allman put 41 sealers through the same tests in Testing 41 Polymer Clay Sealers at The Blue Bottle Tree, brand by brand. Her Understanding Polymer Clay Glazes, Sealers, and Varnishes is the place to start if you are not sure whether you need to seal at all.

• Cernit reference: CE3050250001C
• Finish: Matte
• Size: 250ml bottle
• Base: Water-based