No matter what type of things you like to make with polymer clay, sooner or later the question of sealers comes up. It’s common for new polymer clay crafters to have misconceptions about the subject of varnishes, sealers, and clear coatings. Confused readers often ask me about the differences between types of coatings, particularly how and when you’d want to use them. In this article, I’ll try to clear up confusion and help with understanding polymer clay glazes, sealers, and varnishes.
Note: I recently tested 41 different glazes, sealers, and varnishes on five different brands of clay. You can see which of them scored well, and which got sticky or peeled off. I found that each product behaved differently on each brand of clay. Varnishes and dimensional glazes have high failure rates when used on polymer clay.
Sealers are Not Necessary
Polymer clay, when cured, is vinyl – similar to a kiddie pool, tablecloth on your deck table, or beach ball. We would never think of varnishing or sealing a beach ball to protect it, right? Likewise there’s no need to seal polymer clay. Adding a clear coating, glaze, or varnish will not make a polymer clay project more durable, waterproof, weatherproof, or heatproof. It will not make a project stronger or protect against breakage. If anything, adding a coating to polymer clay increases the likelihood of it being ruined. Most polymer clay glazes, sealers, varnishes, or clear coatings can become sticky, peel easily, turn cloudy, or crack. This will depend on the brands involved and the conditions they’re exposed to.
You only need to seal and protect what you put ON the surface of your polymer clay project. When you apply mica powders, chalks, glitter, or metal leaf to the surface of your polymer clay project, it will need to be protected if the item is subject to wear. Note that light dustings of chalk or mica, such as rosy cheeks on a sculpture, do not need to be sealed. The same holds true for dots of paint and antiquing in the recessed areas of a design.
Polymer clay is not glossy after baking. You can sand, buff, and polish the clay itself (see below), or you can apply a glossy varnish. To make your clay project less shiny, you could apply a matte varnish. Note that adding a glossy varnish can make translucent polymer clay seem more clear. Just like wetting a beach pebble, a glaze or varnish can make clay appear brighter and/or more translucent.
This includes artists’ varnishes, wood varnishes, glazes sold by the clay manufacturers themselves, and even floor finishes. This broad group of products are typically clear to milky white liquids. Some are off-white. Once dried, most will form a stretchy plastic film over your work. It’s best to use a soft brush and apply several thin coats. Brush strokes can be an issue with this category of finish. Applying varnish to heavily textured projects can result in pooling and air bubbles. Varnishes do not camouflage surface imperfections such as fingerprints, rather, they accentuate them. Varnishes are inherently glossy, but can be made to have a satin, semi-gloss, or matte finish by using matting agents. Matting agents are particles that dull the shine of the varnish. Always stir these containers before use as the matting agent can settle in the bottom, leaving just the glossy varnish at the top of the bottle. I’ll now break down this Varnish category into two types, Acrylic Varnish and Polyurethane Varnish.
Best for: Sealing surface treatments, creating a glossy effect, and enriching translucent projects.
In this category, you’ll find artist’s acrylic varnishes, craft store varnishes, and polymer clay brand glazes. Acrylic varnishes contain acrylic polymer emulsion, which is an acrylic resin suspended in water. To save costs, they may also contain vinyl acrylic, vinyl stearate, vinyl acetate, polyurethane, or even poly-vinyl acetate (PVA, such as in white glue). The specific formulas are usually a secret, so you’ll never know exactly what is in the varnish you choose.
The only reason this matters is that some of these plastic resins are softened by the plasticizers in polymer clay. (Contrary to myth, plasticizers stay in polymer clay. They do not bake out.) This is why some varnishes, glazes, and sealers work beautifully on wood and paper but become soft or sticky when used on polymer clay. The brand of clay you’re using will make a difference, and some clay-varnish combinations will give you a sticky finish. For this reason, you should always test your particular varnish with the clay you’re using before trusting it to a large or important project. (The same holds true for acrylic paint, by the way.)
I’ve separated the polyurethane varnishes because they are marketed differently. But please know that these varnishes still contain acrylic resins. For example, Varathane‘s resin is an acrylic modified urethane. By the same token, many acrylic varnishes contain urethane as part of their resin makeup. So the distinction between these two categories is more one of marketing than chemistry.
Just as with acrylic varnishes, polyurethane is a water-based brush-on varnish and is glossy by nature. Matte version are created by including matting agents. These varnishes are typically clear to off-white, can leave brush strokes, and dry clear and flexible. Depending on the resins included, some brands of polyurethane can be softened by the plasticizers in your polymer clay. Often, as in the case with Varathane, they won’t cure rock-hard, but it won’t be sticky either. Other varnishes can be sticky, though, so always test a new varnish with the clay you’re using.
Clear-coat resins are poured onto the surface of your project and then they harden to form a hard, durable, and thick clear coating. Resin coatings are quite thick and syrupy and can be frustrating and messy to use. Resin is self-leveling, which means that you need to let it sit for a while so that the surface becomes even. Bubbles can be a problem, but you can usually pop them by waving a heat gun over the top. And just like honey dribbling off your biscuits (scones to you Brits), resin has an annoying way of running off the surface of your project and making a mess. Instead of using a brush, resins are usually poured on and the sticky liquid is spread on the surface with a toothpick or needle tool. You will use a lot of paper towels with resin projects. Trust me on this. 🙂
Resins are quite hard after curing, and are crystal clear. The surface will be extremely glossy and can’t be easily peeled or lifted from a project. While you can apply resin to curved pieces, it is an advanced technique, so I only recommend applying resin to flat pieces until you have a really good feel for how to use it. Resin is lovely on sparkly or mica covered projects as it will intensify the sparkle. Resin is a rewarding finish, but it has a huge learning curve and your first few projects will likely incur a few tears and swear words. Always apply resin after baking your polymer clay project. It cannot be baked. There are three types of clear-coat resins as follows.
Best for: Giving flat pieces a thick, glossy finish. Can have a magnifying effect, giving deep dimension to glittery and mica covered projects.
Common brands of this resin are Envirotex Lite, Amazing Clear Cast, Little Windows, and ICE Resin. Epoxy resin consists of two parts, part A and part B, which are mixed in equal portions. Once mixed, a chemical reaction begins and the resin gradually hardens. It takes about 24-36 hours to fully harden. Epoxy resin will not cure fully if the mixture is incorrect or if the mixture is not fully mixed before pouring. You can apply more coats.
Common brands of this resin are Lisa Pavelka’s Magic Glos and UltraDome. These resins are very similar in function and application to the epoxy resins, but they cure within 5 minutes when exposed to UV light using a special lamp or a bright sunny day. If you’ve ever had gel nails applied, you’re familiar with the technology here. Interestingly, UV resins are also used as clear-coats for automotive use as well. UV Resin is super easy to use as there’s no mixing. Just apply to your project, wait for it to level, remove bubbles, and cure. But it can still be messy. And the cure will be inhibited and the surface will remain sticky if you use it over paints or varnishes.
You won’t commonly see polyester resin used in the craft world as it’s pretty noxious. It’s used similarly to an epoxy resin, except that you use a large volume of resin (part A) and a small volume of hardener (part B). I’ve not used this since I was a kid and helped my dad repair a fiberglass tank, so I’m only mentioning it here as an FYI.
Sort of like a cross between a glue and a varnish, dimensional glazes are similar to resin in that they’re syrupy and they can be applied in a thick coating. Common brands are Diamond Glaze, Triple Thick, Mod Podge Dimensional Magic, and Aleene’s Jewelry Pendant Gel. You may have seen these liquids used to fill pendant bezels. When poured thick, they will take a few days to fully dry, but they should dry clear and have sort of a resin effect. Dimensional glazes can be applied with a brush and used as glaze or varnish. All dimensional glazes are glossy – there are not matte versions available.
I am not fond of using this class of products with polymer clay. They are notorious for absorbing humidity and becoming cloudy over time. Some brands get sticky on polymer clay. I’m testing the above four brands and three of them are already failing. The fourth is holding up well, so far, but it’s also the one that my readers tell me is the worst. So I don’t hold much hope for using dimensional glazes with polymer clay.
Best for: Thick, glossy coatings. However, I don’t recommend these due to poor performance on polymer clay.
Renaissance Wax has persuasive marketing that’s convinced many people, including many polymer clay artists, that it’s an all-purpose protective material. That’s not exactly true. It is a high quality microcrystalline wax used to coat metals against corrosion and tarnish. It will also enrich the appearance of materials such as tortoise-shell or ivory. Because it’s acid-free, it doesn’t contain chemicals that can degrade artifacts. It is archival. But that doesn’t mean it’s a superior protective coating for all purposes. It can build up and attract dirt.
Renaissance Wax does a lovely job enriching a smooth polymer clay surface. Just apply a thin coating, let dry for a few minutes, then buff with a cloth. This will work sort of like wetting a beach pebble and can enrich a dark clay surface. Wax can also change the appearance of surface treatments, such as paint, chalk, and mica powders. I like to think of waxes as being a surface treatment themselves and not a protectant.
Because waxes apply as a microscopically thin layer to polymer clay, they will do nothing to protect mica powder, glitter, paint, or metal leaf from wear or abrasion, and can even remove them. You will not get a glossy shine with a wax. Instead, you’ll get a burnished sheen, but only when used on an already smooth surface. Wax applied to a textured surface will be white and unattractive.
There are other waxes which work just as well. Neutral shoe polish and paste wax both work nicely on polymer clay to create a warm, enhancing sheen. But frankly, so does Vaseline, at a tiny fraction of the cost.
Best for: Deepening and enriching dark colors, giving a warm sheen to smooth clay.
Liquid Polymer Clay
Liquid clays are essentially polymer clay without the binders that turn it into a putty. They have many uses, such as acting as a glue, a transfer medium, and a clay thinner. You can also use liquid polymer clays as a glaze or sealer. Liquid clays have the advantage of always being 100% compatible with polymer clay and will not result in stickiness. There are three main well-known brands of liquid polymer clay.
Best for: Encasing inclusions, sealing surface treatments. Always clay-safe.
Kato Liquid Polyclay
Also known as Kato Liquid or Kato Sauce, this liquid has the consistency and appearance of thinned white glue. To use as a varnish, apply a very thin coat with your finger or a brush. Allow to level, then bake. After baking, you will need to use a heat gun to make the thin layer of clay crystal clear and shiny.
Fimo Liquid used to be called Fimo Deco Gel. It is a syrupy, runny, cloudy liquid. Apply to your clay, allow to settle, and then bake. It will become clear during baking. Of the three main brands of liquid polymer clay, Fimo Liquid is the only one that will remain fairly clear when cured in a thick layer. To use as a varnish, apply to the clay in a thin coating. Allow to settle and level, then bake. A heat gun will make it more shiny, but it won’t be as shiny as Kato Liquid.
Translucent Liquid Sculpey
This stand-by, also called TLS, is similar to the other liquid clays and can also be used as a glue and thinner. But it does not bake particularly clear. Thick layers will be opaque. It can be effectively used as a varnish, however, by using a cosmetic sponge to dab the TLS onto your clay surface. Wait a few minutes for it to settle and level (a bit) and then bake. Afterward, thin layers will be invisible, but the surface will be matte. If you use a heat gun on cured TLS, it will become glossier, giving a satin finish.
Spray varnish seems like such a perfect solution. Just take your project out on the porch, spray it real quick, come back in and you’re done. But sadly, very few brands of spray varnish will work with polymer clay. MOST of them will be softened by the plasticizer in polymer clay and stay sticky. PYM II is a unique spray acrylic coating that does not stay sticky and works well with polymer clay. PYM is not glossy or matte, rather, it’s sort of a satin finish. Multiple coats will give a more durable finish, but do let it dry between coats. Many thin coats is far better than one thick one. Read about my experiments with spray sealers here.
You will want to use a spray varnish when you need to quickly seal and stabilize surface treatments such as mica powders, chalks, and glitter. Sprays also work nicely to apply a varnish coating onto textured surfaces.
Best for: Sealing surface treatments, especially mica powders. Great on textured items where varnish would pool.
Embossing powder is a wax-like powder that is traditionally applied to a design on paper, then melted with a heat gun to create a raised, “embossed” design. Clear embossing powder is popularly used in crafts because it can be melted in a special melting pot and then used as a clear coating material. A common variant of this embossing powder is called Ultra Thick Embossing Enamel (UTEE). UTEE can be used to coat polymer clay projects, giving a thick, clear surface like resin. I don’t recommend UTEE for glazing and varnishing purposes with polymer clay because it isn’t very durable. It’s not very flexible and will readily flake off baked polymer clay. It can turn cloudy over time. It is also easily scratched.
Best for: Not recommended as a polymer clay glaze, sealer, or varnish.
Mod Podge is a decoupage medium that paper crafters use as a “sealer”. Therefore new polymer clayers sometimes advocate its use as a glaze, sealer and varnish as well. Mod Podge is a variety of thinned white PVA glue, similar to Elmer’s glue. It is available in glossy, satin, and matte versions. It is white and dries clear. But Mod Podge does not make a good polymer clay glaze or varnish. It is very difficult to apply without obvious brush strokes. After drying, if it dries at all, it can stay sticky in high humidity applications. Water left on the surface will turn white and the Mod Podge will soften. I strongly recommend this not be used as a polymer clay glaze, sealer, or varnish.
Woodworkers know that cyanoacrylate (CA) can make a fantastic coating for wood. But it works very well with polymer clay as well. Cyanoacrylate is also known as superglue. And yes, some varieties of CA are specifically used to create a tough, durable, and clear surface coating. Because a lathe is typically used, it’s beyond the scope for most routine polymer creations. But it’s something I want to explore further at some point. A CA finish is what Ed Street uses to put a super-smooth finish on Toni Ransfield’s pens. You can read more about the process here on Toni’s site.
Liquid Fusion is a urethane glue that is slightly amber colored and crystal clear. It can be poured on the surface of flat polymer clay and left to dry. It will take several days, but you’ll be left with a smooth, glossy, hard finish similar to resin.
Sanding and Buffing
When done well, a sanded and buffed smooth polymer clay surface is considered by many to be the best finish. Sanding and buffing is hard to beat because there will never be any brush strokes, stickiness, cloudiness, or other chemical incompatibilities. Smoothly sanded polymer clay is a tactile pleasure that you can’t help but rub between your fingers because it just feels so nice. Unbuffed, a sanded finish will be completely matte. Buff it a bit for a warm satin sheen. If you properly buff smooth polymer clay with a high speed buffer, you can get a finish that is just as smooth and glossy as resin or glass. In fact, it’s quite difficult to get this kind of flawless glossy surface with varnishes or glazes. Sanding and buffing has a reputation for being difficult and can lead to painful fingertips, but it doesn’t have to be that way.
If you want to know how to get an absolutely perfect shine on polymer clay with sanding and buffing, with minimal effort, I recommend that you check out my Sanding and Buffing eBook. It is a comprehensive 120 page guide that explains everything I know about sanding and buffing. I discuss the types of sandpaper, kinds of buffers, using tumbling machines, Dremel, varnishes, and even whether you even need to sand at all. Here’s where you learn more about the Sanding and Buffing eBook. If you want a shiny, smooth polymer clay surface, this eBook will get you there.