I tested 41 polymer clay sealers, varnishes, glazes, and dimensional glazes on five brands of polymer clay and watched them for five months. The results were not what I expected. Most of them failed on at least one brand of clay, and only a small handful worked well on all five.

If you just want the quick answer, start here. Polymer clay is durable vinyl and does not need to be sealed. You only need a sealer to protect a surface treatment like paint or mica powder. For that, the varnishes that perform best in my studio are CrystaLac Brite Tone and Varathane. And if you want a thick, hard, glossy coating, that’s a job for resin, not varnish. Resin is a thick plastic overlay. Varnish is a thin, form-fitting plastic skin. When I need that thick glossy look, I reach for UV resin.

No polymer clay group escapes the questions about sealers, varnishes, and glazes. Which ones are “clay safe”? Which ones turn sticky, get cloudy, or peel off? There are lots of opinions and few solid answers, and the only way to really know is to test. So that’s what I did. (I use the words sealer and varnish interchangeably here. I found no difference.)

A note on these results. I ran these tests in 2016. Some of the products have since been discontinued or renamed, and I’ve left them in as a record and noted what has changed. The clay formulas don’t appear to have changed, but neither clay nor varnish makers announce every tweak, and I can’t retest everything every six months. So treat these results as a strong starting point and test your own bottle before an important project.

How I Tested the Sealers

I knew from my spray sealer tests that different brands of clay react differently, so I tested on Sculpey III, Kato Polyclay, Premo, and Fimo Professional. Syndee Holt asked me to add Souffle, and I was happy to. (Kato Polyclay is no longer made, but most clayers still have some on hand.) Black and white clay showed any cloudiness or yellowing, and colored clay was an extra check.

For each brand I made a master cane of about 4 lbs (1800g) in black, white, and primary colors, reduced it using square dowels, and sliced it into test tiles with my LC Slicer. I baked the tiles according to each label, wiped them with alcohol to remove surface oils, and labeled the backs with a paint marker.

I stirred each varnish with a new wooden stir stick and brushed three coats onto each tile using identical strokes, letting each coat dry to the touch (usually about 30 minutes). I did not heat set the tiles. They sat flat on an open rack in my studio for five months, from summer through autumn into winter, with all the temperature and humidity changes that go with that. I checked them at one week, one month, and five months.

What I Looked For

For the sealer itself, I noted color, clarity, thickness, odor, and drying speed. On the tiles, I checked gloss level, smoothness, cracking, clouding, yellowing, scratch resistance, peeling, stickiness, and coverage. I dug at each coating with my fingernail to see if it would scratch or peel, and pressed a fingertip on each tile. If the tile stuck to my finger at all, it was rated sticky.

There’s judgment involved here. How much scratching or cloudiness is too much? I would still say yes to a sealer with one weak spot if it was really good everywhere else. But stickiness at any point after the initial drying time was an automatic no, even if it went away later. So was a coating that scratched off with little effort. To be a top pick, a product had to work well on all five brands.

Results by Product

I’d love to give you a simple yes or no for each product, but most of them acted so differently on the various clays that I can’t. Here’s a summary of each one. For every score on every brand, see the spreadsheet.

Sprays

Sprays performed so poorly overall that I strongly recommend you don’t use them. For more, see my spray sealer tests.

• Krylon Preserve It! Never dried. Extremely sticky and goopy on every brand.
• Krylon Workable Fixatif. Pebbly and uneven. Sticky on Premo, Fimo Pro, and Souffle.
• Molotow Premium Spray. Only sticky on Fimo Pro, but it sprayed on pebbly and never made a smooth surface.
• PYM II. Worked beautifully on every brand, as it has in all my tests. Sadly, it’s no longer on the market.
• Helmar Crystal Kote. Hard to find now. The gloss version works on everything except Fimo Pro. The matte version is invisible and gives a matte finish. More about Helmar Crystal Kote.
• Upol #1. A clay-safe automotive clearcoat, but it’s smelly!

Matte Varnishes

• Cernit Matte Transparent Varnish. One of the very few that resists scratching on Kato. A lovely, dry-feeling, durable finish on every clay, though it’s really more satin than matte.
• Swellegant Clear Sealant. Now sold as Sculpt Nouveau Smart Coat Clear Sealer, and the same product as Final Coat. This light-bodied sealer is perfect for fixing surface treatments. It beads up on Kato but is nice on the other brands.
• DuraClear Ultra Matte. My favorite matte varnish. Light-bodied and truly matte. Scratch resistant on Fimo Pro and Souffle, and fine for low-wear pieces in Sculpey III and Premo. Not for Kato, where it scratches and peels off easily.
• Golden Matte Polymer Varnish with UVLS. Popular in the polymer community, but it scratches off Sculpey III, Kato, and Premo very easily and gets sticky on Fimo Pro. Better on Souffle, but it can still be scratched off.
• Duncan Matte Sealer. A ceramics product. Sticky on Premo, Fimo Pro, and Souffle, and scratches easily from Sculpey III and Kato.
• Mod Podge Matte. Terrible brush strokes, not very matte, and it turns white when it gets wet. There are better choices.
• Daler-Rowney Soluble Varnish, Matte. A painting varnish I had on hand. Sticky and gooey on every brand.
• Liquitex Matte Varnish (red label). Peels easily from every clay, and sticky on Premo, Fimo Pro, and Souffle.
• Genesis Heat Set Matte Varnish. More a liquid clay than a varnish. Chemically great on every brand, but it doesn’t self-level, so your sponge or brush texture shows. The Genesis line is no longer made.

Satin and Semi-Gloss Varnishes

• Final Coat. Now sold as Sculpt Nouveau Smart Coat Clear Sealer. A light-bodied sealer that works nicely as a fixative for mica powders. Not heavy-duty protection. Good on every clay except Kato, where it beads up or scratches.
• Liquitex Satin Varnish (red label). Cloudy on dark colors, peels easily from every clay, and sticky on Premo and Fimo Pro.
• Sculpey Satin Glaze. Obvious brush strokes (especially on Fimo Pro) and cloudy on every clay. Unusually, it resists scratching on Kato, and on Souffle too.
• Polycrylic Clear Satin. A wood varnish with a vinyl-like, rubbery feel. Good on Sculpey III, Fimo Pro, and Souffle. Scratches very easily from Kato and Premo.
• Varathane Polyurethane Satin. A polymer clay favorite. Dry feel and no stickiness on any brand. It can be scratched off if you dig at it on every brand but Fimo Pro.
• Future Acrylic Floor Finish. Light-bodied, completely clear, and never sticky on any brand. More semi-gloss than gloss unless you add coats. It scratches off most clays and isn’t very durable. No longer sold.
• Pledge Floor Care Finish. The replacement for Future and nearly identical, just a smidge glossier with a different smell. It doesn’t turn white when it gets wet.

Gloss Varnishes

• Varathane Polyurethane Gloss. This much-loved sealer is dry and lovely on every brand. It can scratch and peel if you dig at it, but it’s durable enough for all but the roughest handling.
• Pearl Ex Varnish. No mica in it, just the same maker. A satin sheen, a lovely dry feel, and scratch resistant on every clay. Slight orange-peel texture on Fimo, but wonderful on the others.
• Darwi Vernis. An alcohol-based varnish from the makers of Cernit with a thick, glossy coat. Scratches easily from Kato, and it turns white and crackles when flexed. Great on beads or anything that should be hard and shiny, but not on thin or flexible pieces like cutter earrings.
• Ronseal Interior Gloss Varnish (UK). A hardware store polyurethane that’s remarkable and scratch resistant on Sculpey III, Kato, and Premo. Sticky on Fimo Pro and Souffle. (Some readers find it sticky on Premo too, so test first!)
• Wilko Quick Dry Varnish (UK, may no longer be sold). Lovely on Sculpey III, Premo, and Souffle. Peels from Kato and sticky on Fimo Pro.
• Media Gloss Varnish. I found it at HobbyCraft in the UK, but it’s sold in the US too. Beads up on Kato, Premo, and Fimo Pro and scratches easily on all but Souffle. On Souffle, though, it’s a phenomenal, durable high gloss. Highly recommended for Souffle only!
• Fimo Gloss Varnish. Beads up and goes cloudy, but makes a good varnish for Fimo Pro and Souffle.
• Polycrylic Clear Gloss. Available everywhere in the US. A vinyl-like feel and not very glossy. A good finish on all but Kato. Satin on Fimo Pro, glossier on Souffle.
• DuraClear Gloss Varnish. Beads up on every clay but smooths out with several coats. Scratches easily off Kato. A nice feel on Fimo but it made the tile curl, and it seemed great on Souffle until fine bubbles showed up. Few things work on Fimo, so it’s worth trying there.
• Golden Polymer Varnish with UVLS. Peels easily from every clay, beads up on Kato, Fimo, and Souffle, and is sticky on Fimo Pro. I know it’s popular, but it scored badly here.
• Cernit Transparent Varnish, Glossy. Beads up on every clay, and so badly on Kato that you can’t get any coverage at all. Cloudy on Kato and Souffle.
• Sculpey Gloss Glaze. Obvious brush strokes and distinct cloudiness on every clay. By five months it had crackled on every brand, most obviously on Kato.
• Liquitex Gloss Varnish (red label). Beaded up on every clay. Cloudy on Sculpey III, Premo, and Souffle, sticky on Fimo, and fine bubbles on Souffle. There are better varnishes.
• Duncan Gloss Sealer. Another ceramics sealer. Terrible brush strokes and sticky on every brand.
• Gloss Medium and Varnish (green label). Sticky on every clay tested. Do not use.
• Mod Podge Gloss-Lustre. Very glossy, but terrible brush strokes, and it turns brilliant white when it gets wet. Not really suitable for polymer clay.

Dimensional Glazes

• Aleene’s Jewelry Pendant Gel. Very glossy. Shows scratches and can peel if you pick at it. Smooth on most clays, but sticky on Fimo Pro.
• Triple Thick. The glossiest product I tested. Readers tell me it turns sticky, though I didn’t see that on any brand. Blotchy brush strokes, every tile curled, and a rubbery feel that shows fingerprints, especially on black. I also had terrible results with it here.
• Mod Podge Dimensional Magic. Brush strokes and bubbles make a smooth coat impossible. Sticky on Premo, and it shrinks over time and makes the clay curl.
• Diamond Glaze. Dries blotchy with brush strokes and bubbles. Sticky on Sculpey III, Premo, and Fimo Pro, and it shrinks and makes the clay curl.

Best Sealers for Each Clay Brand

Here’s every product that performed well on each brand of clay. A check means it passed on that clay.

Product	Sculpey III	Kato (no longer made)	Premo	Fimo Pro	Souffle
Varathane Satin	✓	✓	✓	✓	✓
Varathane Gloss	✓	✓		✓	✓
Pearl Ex Varnish	✓	✓	✓	✓	✓
Cernit Matte Varnish	✓	✓	✓	✓	✓
Helmar Crystal Kote Matte (hard to find)	✓	✓	✓	✓	✓
PYM II (no longer made)	✓	✓	✓	✓	✓
Genesis Heat Set Matte (no longer made)	✓	✓	✓	✓	✓
Polycrylic (satin and gloss)	✓		✓	✓	✓
Final Coat (now Smart Coat)	✓		✓	✓	✓
DuraClear Ultra Matte	✓		✓	✓	✓
Cernit Gloss Varnish			✓	✓	✓
Sculpey Satin Glaze	✓	✓			✓
Swellegant (now Smart Coat)	✓		✓		✓
Wilko Quick Dry Varnish (UK, may be gone)	✓		✓		✓
Ronseal Interior Gloss (UK)	✓	✓	✓
Aleene’s Jewelry Pendant Gel		✓	✓		✓
Fimo Gloss Varnish				✓	✓
DuraClear Gloss				✓
Media Gloss Varnish					✓
Golden Polymer Varnish UVLS (matte)					✓

My Top Picks

There’s no single best sealer. It depends on the effect you want, and few of these products are alike. Some are thick and glossy, some are thin and matte. Here’s where I land.

• Varathane is an excellent all-purpose varnish that never got sticky on any brand. If you use several brands of clay and only want one sealer, this is probably your best bet. It isn’t the top performer on any single brand, though.
• Pearl Ex Varnish did well on every brand, a bit less so on Fimo Pro.
• Cernit Matte Varnish is another standout, though it’s more satin than matte.
• DuraClear Ultra Matte by Americana gives a luscious dead matte finish on every clay except Kato.
• Sculpt Nouveau Smart Coat Clear Sealer (sold earlier as Final Coat and as Swellegant) is a super light-bodied sealer for fixing mica powders. It goes on quickly without much brushing and dries in no time.
• In the UK, Varathane is available from Amazon, or try Ronseal Interior Gloss Varnish from Homebase, which performs beautifully on all but Fimo and Souffle.

I used to recommend Golden Polymer Varnish and Liquitex Varnish. They worked for me, but that was before I tried them on multiple brands of clay. They did poorly in these tests, so I no longer recommend them and have updated those articles.

Why Your Results Might Differ

Did your favorite sealer score badly, or did one I recommend fail you? That’s not surprising. Manufacturers tweak their varnish and clay formulas all the time, formulas differ between regions, and even different production lots can behave differently. Contaminated brushes can change results, and so can underbaked clay, which is a common cause of sticky paints and varnishes. Paint adds another layer of chemistry, too. Many paints stay sticky on polymer clay, and a varnish on top makes things even less predictable.

Phyllis Cahill ran her own tests of how well sealers stick to different clays and surface treatments, and her results differed from mine to a degree. That’s the point. Always test your bottle of sealer on the brand of clay you’ll be using, even if it has worked for you on another brand, and especially before an important project.

Do You Even Need a Sealer?

As you can see, no sealer works perfectly in every situation on every brand of clay. Sealers add complexity and bring in the chance of brush strokes, peeling, stickiness, and cloudiness. Polymer clay is a durable vinyl plastic, and the only things that need sealing are surface treatments you put on the clay. Sealers can change the gloss level of your work, but if you want a super smooth, glass-like finish, the smoothest and most durable way is to sand and buff your clay.

You can also use liquid polymer clay as a clear coat and fixative. Translucent Liquid Sculpey makes an excellent matte fixative. Very lightly dab it on with a cosmetic sponge and bake again. Yes, this works over paint and other surface treatments. Liquid Kato Polyclay can make a super smooth, glossy finish when cured with a heat gun. There’s a learning curve, and Debbie Crothers’ video tutorial on curing Kato liquid clay takes the mystery out of it. Resin (epoxy or UV) is another good coating for polymer clay, though I didn’t test resins here. You can read my resin article for that.

Thank You

I bought most of the clay and sealers for these tests, but a few people helped with the cost. Sculpey sent the Souffle for the Souffle cane. Wendy Orlowski of Shades of Clay provided the Final Coat. Marina Taenkova of Marka Decor provided the Cernit varnishes. And Christi Friesen sent the Swellegant sealant. Thank you all!