Polymer Clay Finishes: Matte, Satin, and Gloss

Cured clay does not have to be coated with anything. That is the first thing to know about polymer clay finishes, and it surprises many beginners who assume a varnish is the last step of every project. A finish is a choice about how the surface looks: flat and soft, gently glowing, or bright and reflective.

There are two routes to any of those looks. One works on the clay itself, by sanding and buffing. The other adds a layer on top, such as a brush-on varnish. The first route changes nothing about what the piece is made of. The second depends on a product whose behavior on your particular clay you cannot know until you test it.

Matte, Satin and Gloss at a Glance

Finish	How it looks	Without a coating	With a coating
Matte	Flat, no highlight, shows color evenly	Leave the cured surface as it is, or sand to a fine grade and stop	A matte varnish, applied thinly
Satin	A soft, wide highlight	Sand through fine grades, then buff by hand with a soft cloth	A satin varnish, applied thinly
Gloss	A sharp, bright highlight	Sand through the finest grades and buff for longer and harder	A gloss varnish or a clear resin

The three are points on a scale, not separate categories. How far along the scale a piece ends up depends mostly on how smooth the surface was before you started.

Start with the Surface

No finish hides flaws. Gloss does the opposite: a shiny surface reflects light in a clean line, and every fingerprint, scratch and speck of lint bends that line and becomes obvious. A matte surface is far more forgiving.

So the work of finishing begins before curing, with smoothing away fingerprints and tidying edges, and continues afterward with wet sanding through progressively finer papers. Lint, bubbles and other marks that were cured into the piece are dealt with in the troubleshooting guide. A fully cured piece also takes a better finish, because under-cured clay tends to stay weak and can be damaged by sanding and buffing.

Finishing Without a Coating: Sanding and Buffing

Buffing is rubbing the cured, sanded surface until it develops a sheen. It adds nothing to the piece, so there is nothing to peel, yellow or turn sticky later.

1. Sand to at least a very fine grade. Buffing polishes what is there. If scratches remain, you will get shiny scratches.
2. Rinse and dry completely. Any grit left on the surface will scratch it again as you rub.
3. Rub with a soft cloth. Use clean cotton, denim or microfiber. Hold the piece firmly and rub briskly in small arcs, turning it so every part gets the same attention.
4. Check under a light. A satin glow appears first. Continued buffing on a very finely sanded surface brings it closer to gloss.

Domed shapes such as beads and cabochons buff most easily, because the cloth touches the whole curve. Textured surfaces cannot be buffed evenly, since the cloth only reaches the high points.

Brush-On Varnishes and Other Coatings

A coating is the practical route for textured pieces, for surface decoration such as paint, powders or metal leaf that would rub off, and for anyone who wants a look that buffing cannot give. The common types are water-based varnishes sold in matte, satin and gloss, liquid polymer clay used as a clear layer and cured again, and clear resins that are poured or domed onto a surface.

Treat every label claim as applying to the product on its own, not to the product on your clay. Follow the manufacturer’s directions for application, drying, ventilation and safe use. Resins in particular come with their own safety instructions, which should be read in full before opening the bottles.

How to Apply a Thin Coat

1. Clean the piece. Wipe away sanding residue and skin oils with a damp cloth and let the surface dry.
2. Use a soft, flat brush. Stiff bristles leave ridges. Load the brush lightly and wipe the excess on the rim of the container.
3. Brush in one direction. Lay a thin, even coat across the surface with long strokes. Do not go back over an area that has started to dry, because that drags the film and leaves marks.
4. Watch the edges and holes. Varnish collects there and dries as a thick bead. Lift any pooling with the tip of the brush.
5. Let it dry as the label directs. Rest the piece where dust will not settle on it. Add a second thin coat only if the label says to and the first is fully dry.

Two thin coats give a better result than one thick coat. Thick coats trap bubbles, sag at the edges and are the most likely to stay soft.

Test on a Scrap First

Whenever you cure a project, cure a small scrap of the same clay alongside it. That scrap is your test piece.

• Coat half of the scrap and leave the other half bare, so you can compare color and sheen.
• Let it dry for as long as the label says, then leave it for several more days before judging it.
• Press a fingertip on the coated half. Tackiness, a fingerprint left in the film or a cloudy patch all mean the combination is not working.
• Flex the scrap slightly and scratch the coating with a fingernail to see whether it lifts.

Write on the back of the scrap which clay and which product it carries, and keep it. A small collection of labeled test pieces answers most finishing questions faster than guessing.

Which Finish Suits Which Project

Matte suits modern, flat shapes and patterned slabs, where reflections would compete with the pattern. It is the usual choice for polymer clay earrings cut from a slab. Satin suits pieces that are handled and admired up close, such as handmade beads and pendants, because it shows off color without showing every mark. Gloss suits small domed pieces and details you want to look wet or glassy, such as the icing on miniature food, and it works best as an accent on part of a piece.

Whatever you choose, treat finished pieces gently. No finish makes a piece indestructible, and how any coating holds up over time depends on the product, the clay and how the piece is used.