Do You Have to Seal Polymer Clay?

Do you have to seal polymer clay? When is it a good idea, and when can it ruin your work? Learn more at The Blue Bottle Tree.If you read or follow any polymer clay groups and forums, you’ll notice that one of the most common questions asked is “Which polymer clay sealer should I use?” Everyone has their favorite sealer, and the answers differ depending on your need and the availability of products where you live. But perhaps we’re asking the wrong question. I think the first question needs to be, “Do You Have to Seal Polymer Clay?”

When to Seal Polymer Clay

People often want to seal their polymer clay creations for protection against the elements or from damage during use. In most cases this is unnecessary. Once it’s been properly baked or cured, polymer clay becomes a durable solid plastic that is waterproof, shock resistant, and fairly tough. Because it’s such a durable material, it probably won’t surprise you to learn that it’s actually more durable than any sealer that you will put on it. Sealers, varnishes, and finishes do have their purpose, but bare clay itself does not need to be sealed for protection. Here are some reasons why you would want to seal polymer clay:

Protect Surface Treatments

When you embellish your polymer clay project with chalks, paints, mica powders, metallic pastes or metal leaf, those treatments are sitting on the surface of the polymer clay and are not nearly as durable as the polymer clay itself. Projects using surface treatments must therefore be sealed for maximum durability. In the case of jewelry, the wearer must also be protected from any pigments, dyes, and mica coming off on their clothes or skin. If the project is purely decorative and will merely be sitting on a shelf, sealing is not imperative. But keep in mind that cleaning any accumulated dust would likely cause the surface treatments to be disturbed.

Polymer clay artists often use acrylic paint to color and embellish their projects. Does acrylic paint need to be sealed? Well, it depends. Paint used to antique a textured surface is mostly rubbed off and the remaining paint is fairly well protected down in the “nooks and crannies” of the piece. In that case I would not seal it. But thin layers of acrylic paint can sometimes peel or scrape off, or will come off if the piece is washed. In those cases I would use a sealer. Even when the layer of paint is thick and strong, a sealer might give a brighter, more durable coating much in the same way that a clear coat is used over the colored paint on your car. You’re going to be the best judge for your own particular project.

Change the Gloss Level

Although different brands of clay have different native gloss levels, and the technique you use can leave you with a matte or glossy surface, the easiest way to change the gloss level of your finished piece is to use a sealer that has the desired type of gloss level. Many varnishes come in both glossy and matte varieties. Sometimes you will look at a finished piece and realize that you would like it better matte or glossy and choosing the correct varnish can easily give you the effect you want.

Ease of Cleaning

Polymer clay is not porous like wood or unglazed ceramic. It will not absorb and hold water. Polymer clay can, however, have fine pits in the surface, depending on the method you used to create the piece. Some clay brands, such as Sculpey III and Souffle, tend to have a surface that appears to be porous (this is also why those brands are so great for holding onto acrylic paint). Because of this, dirt and makeup may be difficult to remove from a piece without scrubbing with soap and water. This can also be a problem when clay is created with a finely textured surface. Plus, sometimes the dyes in your makeup can permanently discolor light colored clay beads. In these cases, sealing the clay makes sense.

Intensify Colors or Translucency

Just like a pebble dipped in water becomes more vivid and bright, a coat of sealer can make polymer clay appear more rich, deep, and colorful. This also holds true for translucent clays. They will appear even more translucent when a sealer is used on the surface.

When NOT to Seal Polymer Clay

Sealers and varnishes are wonderful tools to be used when the time is right. But there are reasons why trying to seal your project might not be a good idea. Here are a few reasons.

  1. Many sealers, varnishes, and coatings turn sticky or cloudy over time, ruining your project. What works for one person might very well not work for another. Unless you know how your chosen sealer is going to act, and unless you’re certain you need to be using a sealer in the first place, it might be better to reconsider. Always test some samples before using a sealer on something that’s irreplaceable.
  2. Because most polymer clay varnishes are, themselves, a kind of thin plastic coating, they can often be peeled from the project if you try hard enough. If the product will get lots of abuse, a varnish might not be strong enough.
  3. When making glass-like items, using a gloss sealer is not a substitute for creating a smooth item in the first place. Applying a glossy coat over the top of a project full of tool marks and fingerprints will just accentuate them rather than camouflage them, making your project look sloppy and unprofessional.
  4. Using a sealer on a highly textured item can go badly wrong. I remember waxing my dad’s pickup when I was about 10. I got wax on the black plastic trim. Of course it turned white in the grooves. Bad memories! Polymer clay is no different. Wax is great for smooth surfaces, but it will collect in the small crevices of a textured item and look awful. Liquid varnish such as Varathane will also collect or pool in highly textured areas, leading to a look that very much wasn’t what you had in mind. You can seal textured items with a varnish, but you have to be careful in your application. Don’t just slather it on!

Use the Right Sealer for your Project

There are lots of types of polymer clay sealers and glazes. I use a different sealer depending on the effect I want to accomplish in my finished piece. There are many excellent varnishes, finishes, and sealers out there, and I haven’t tried them all by any means! But here are some tried and true sealers that I can heartily recommend.

Glossy Sealers

Varathane is a brand name of polyurethane varnish available in the US. It has been a favorite varnish with polymer clay artists for many years. It does come in gloss, semi-gloss, and satin, but I find that even the satin is still pretty glossy. I wrote an article about Varathane describing why it’s my favorite sealer and giving sources (including non-US brands of polyurethane).

Pearl Ex Varnish is made by the same company as the well-known mica powders. But this is just a varnish. It works nicely on all brands of clay, but doesn’t give a super glossy finish.

Aleene’s Jewelry Pendant Gel is a glossy dimensional glaze that can be used on most clays, but avoid using it on Fimo as it can get sticky.

Epoxy Resin is a clear, thick coating that is gaining popularity among polymer clayers, for good reason. It is exceedingly strong and durable, more so than any other finish. But it has a long cure time, takes some practice to get used to using, and is known for causing swear words. But once you get the hang of it, it works very nicely. Favorite brands are ICE Resin, Envirotex Lite, and Magic Glos (a brand of UV-cure resin).

Kato Liquid Polyclay can be used as a sealer. Just brush or sponge on a thin coating and then cure in the oven. After oven curing, you can use a heat gun to further cure it to give a crystal-clear, glossy finish.

These finishes work well to create a glossy surface on polymer clay.

Matte Sealers

Translucent Liquid Sculpey is another brand of liquid clay but this has a matte finish when cured. To get this effect, use a cosmetic sponge to dab the TLS onto your piece, then oven cure. Do not cure with a heat gun or the effect won’t be matte.

Cernit Matte Varnish gives a nice, smooth, dry finish on all brands of clay. It’s not terribly matte, but does give a low-sheen satin finish that looks and feels great.

DuraClear Ultra Matte Varnish is a dead matte varnish that has no sheen at all. It performs beautifully on all brands of clay except for Kato.

If you do need to seal polymer clay, these products work well to create a matte finish.

 

For a Natural, Burnished Look

If you like the look and feel of polymer clay that’s been sanded to a very high grit and buffed, you will love the way that adding a coat of wax makes those pieces feel and look. Renaissance Wax is a favorite brand of high quality wax that has a great marketing program and a price tag to match. Don’t get me wrong, I love Ren Wax. But want to know a secret? Paste Wax and Neutral shoe polish will work just the same and have a MUCH better price. Remember, wax doesn’t work well on items with a fine texture (such as when you use sandpaper or a sponge to disguise fingerprints). The wax will collect in the pits and look awful.

Renaissance wax functions exactly like paste wax for use on polymer clay. But it's much cheaper.
I left the sticker on the Renaissance Wax so you could see the cost. The paste wax is an old can I stole from my dad. I don’t think Minwax even makes it anymore. But Johnson’s Paste Wax is readily available and does the same job. Cheaper.

For Sealing Delicate of Textured Surfaces

Sometimes the act of brushing or rubbing on a sealer can disturb surface treatments such as mica powders. And a sealer can actually dissolve the surface treatment, like happens when you put Varathane onto alcohol inks. And sometimes you do want to seal finely textured surfaces without getting air bubbles or pooling. In these cases a spray varnish would be great, but most spray varnishes can cause polymer clay to become sticky over time. There is one brand of spray varnish, called PYM II, that is completely clay safe and really gives a great effect. It sets and stabilizes mica powders and can help seal alcohol inks with a quick, light coat. After that, you can layer subsequent coats to give a thicker seal or you can use another type of sealer. Yes, you can use Varathane or Ren Wax over the top of PYM II.

PYM II polymer clay spray sealer is safe for polymer clay. Read a review at The Blue Bottle Tree.

Sealers to Avoid

Just as there are good sealers on the market, there are also some bad ones. Keep in mind that many of these have been used by many people without any ill effects. But they are also known for having unsatisfactory results as well.

Future Floor Finish, which is now called Pledge Floor Care (and is very similar to the European product Klear) is a very clear, thin, watery finish that is favorite of beginning polymer clay artists. It gives a nice glossy finish, dries clear, smells great, and is readily available. I used it when I first started and I don’t really have much bad to say about it, except that it’s not very durable. There are better options, such as any of the sealers I mentioned above. It’s still a good sealer for things that won’t get any wear, such as figurines and models. But for jewelry, it just dulls down way too fast.

Liquitex Varnish, which I have previously recommended, is an artist’s varnish that comes in gloss, matte, and satin finishes. My tests show, however, that it has lots of brush strokes, turns cloudy on dark colors, and is sticky on some brands of clay. There are better options, such as Varathane or Pearl Ex Varnish.

Dimensional glazes are thick, clear one-part glazes which can be applied thickly to create a glossy, glass-like finish. Some are better than others, but all of them can turn cloudy over time. I think that humidity is a factor. Some brands are Triple Thick, Diamond Glaze, Dimensional Magic, and Aleene’s Jewelry and Pendant Gel. I have found that all of them turn sticky on at least one brand of clay. Aleene’s did show good results on every clay besides Fimo, however, so you might try it. For every person who recommends Triple Thick, I read of another one who says it gets sticky or cloudy. And the reviews I’ve read of Dimensional Magic are sad. I don’t like reading of people’s projects being ruined by a material that was used properly! Success is just too variable with these glazes for me to recommend them universally, aside from Aleene’s.

Nail Polish is often recommended as a paint or glaze by articles in craft blogs. Almost always there will be tears later because the plasticizer in polymer clay softens the polish, making it turn gooey over time. That is, if it dries at all. The thing is, it can be rather hit and miss, perhaps due to the brand of clay or nail polish. It does work often enough that people not knowledgeable in polymer clay will not see what’s wrong with recommending it, and the next person isn’t so lucky! If I had a dollar for every email I answer on this one….

Oil-based Varnishes will often work on polymer clay but will yellow noticeably with time. Cindy Leitz tested Minwax oil-based polyurethane and found that there were no compatibility issues with polymer clay, but it did yellow. This is most noticeable on white clay, of course. Cindy’s result does show the value of testing and making samples. Don’t just randomly grab any can of varnish from the hardware store shelf.

Mod Podge is a glue and decoupage medium that crafters have relied on for working with paper for as long as I can remember. Craft blogs also sometimes recommended it as a sealer for polymer clay.  Just don’t do it. No. Mod Podge is actually made from the same stuff as plain white glue. It’s not a real sealer. You wouldn’t coat your beads in glue, would you? Again, some people have good results with this. But for most of us Mod Podge gets sticky and cloudy in humidity. Just say no.

Spray sealers can also have unpredictable and disappointing results. Sometimes the finish never dries, other times it turns soft and sticky months later. It seems that the plasticizer in baked polymer clay can soften the spray varnish, so even a good trustworthy brand of liquid varnish might not work so well in the spray form on polymer clay. If you need a spray, do yourself a favor and order some PYM II. It’s one of the few sprays that I know of which is absolutely safe to use with polymer clay. Your mileage may vary, of course. I tested 10 different brands of spray sealers and found that only PYM had universally good results on all the brands of clay that I tried.

 

Sealing Myths

New clayers often assume that polymer clay needs to be sealed to protect it against water damage. Cured polymer clay is waterproof and does not need to be sealed against moisture. Most sealers are not fully waterproof (they’re merely water resistant) and can be damaged by prolonged contact with moisture. (A quick wash is not usually a problem for a sealer, though.) If you’re using polymer clay to decorate the outside of drinking glasses, you do not need to seal the polymer clay to make it safe for washing. You do, of course, want to hand wash any decorated glassware, but that’s true for any hand-embellished glassware. Dishwashers can be pretty harsh.

If you’re making polymer clay for use in aquariums or outdoors, a sealer is not only unnecessary but will most often deteriorate well before the clay. Polymer clay is weatherproof and will not crumble or fall apart after exposure to the elements (see the picture of my hearts, below). But the color of some clays can fade in sunlight. I would like to say that a UV sealer will protect your work, but I do worry about the durability of the sealer itself in outdoor conditions.

Another myth is the belief that a sealer will protect a weak polymer clay sculpture against breakage. A coating of varnish or sealer will not make your piece stronger. It will not prevent pieces from breaking off. If small pieces such as ears or arms are not properly adhered in the first place, a coat of sealer will not help things stay in place. The first time the piece is dropped or roughly handled, the ears will snap right off. I suppose if you coated a piece in a thick layer of resin, it would offer structural support. But it would also look pretty gloppy.

These polymer clay hearts have been outside in my back yard for 10 years. The finish has worn off, but the clay is in good condition.
These polymer clay hearts have hung from pots in my back yard for the past 10 years. They were made with Kato. The white one is pearl with no finish, you can see the mildew that’s grown on it. The other three are covered with Pearl-Ex and sealed with Future. As you can see, the finish has crackled and worn off, but the clay is just fine. I think we should use polymer clay more in outdoor projects. Just remember that the sealer will not hold up as well as bare clay will.

Tests and Samples

Regardless of what anyone tells you, though, it’s always best to test any new materials or techniques yourself before you commit to using them with a large or special project that you have put a lot of time into. That way you find out about the problems before anything gets ruined. For instance, Varathane is a fantastic sealer. But you have to learn how to apply it without creating bubbles, and the best way to do that is to do some tests and see what works best for you. Each sealer that I do recommend will come with its own quirks and challenges. Testing and doing sample pieces will help you find the best ways to use them.

Also remember that if you’re selling your work to others, your reputation as an artist depends on the long-term quality of your work. You owe it to yourself and your customers to make sure any sealers you use will hold up over time. Here’s a great article by Staci Louise Smith about how important it is to test your jewelry before you sell it to a customer.

And now I have a favor to ask of you. If you’re reading groups and forums where beginners are dealing with the frustrations of a badly chosen sealer, would you mind pointing them to this post? Maybe we can get the word out there and prevent some sticky beads!

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