Spray Sealer for Polymer Clay

Which spray sealers work well on polymer clay? See the results of the tests at The Blue Bottle Tree.Imagine for a moment working for hours, days, or even weeks on a polymer clay project. You’re proud of all your hard work and so you buy a spray sealer to protect it and give it a nice, glossy finish. You carefully follow the directions on the label and wait for the varnish to dry. But it doesn’t. You wait a day…a week…and still, the spray sealer stays sticky and tacky. You’re horrified to realize that all your work is ruined. So you search online and find that most spray sealers are incompatible with polymer clay. Is there any spray sealer for polymer clay that won’t turn sticky? PYM II is often recommended, but are there others? Certain brands are often recommended but I’ll hear just as many negative reports about them. Why are there so many conflicting reports? You know I had to find out. I bought a bunch of cans and then tested to find the best spray sealer for polymer clay. Here’s what I found out.

Why Use a Spray Sealer for Polymer Clay?

Why would you want to use a spray varnish or sealer with polymer clay? First let me address a common myth. You do not need to seal polymer clay to protect it. Once properly cured, polymer clay is a durable vinyl plastic and is, itself, naturally waterproof. No sealer is more durable than polymer clay. There are two reasons you’d want to use a varnish with polymer clay. One is when you need to protect surface treatments that you’ve used on your clay creations, such as mica powders or chalks. The other is if you want to change the gloss level, making your creation glossy or matte. Read my article Do You Need to Seal Polymer Clay for more information and a list of recommended brush-on sealers.

But sometimes brushing a sealer onto the surface of the clay can disturb the surface treatments. Or perhaps the surface is so highly textured that brushing on a sealer becomes impractical. If you are troubled by too many brush strokes, it can be a compelling idea to use a spray to give a nice even finish.

This article focuses on the basic chemical compatibility of various spray sealers with polymer clay. I picked cans of spray that were readily available in stores near me, plus a few others that I had heard about online. There are hundreds of sprays to choose from and buying them all would have been a cost prohibitive, so I had to trim it down and at least get started testing the most popular ones here in the US. Just because a spray isn’t listed doesn’t mean it doesn’t work. At $8-$22 per can, I had to limit the number tested lest I spend my entire grocery budget on cans of spray sealer!

Summary:

  • Polymer clay does not need to be sealed.
  • PYM II is still the stand-out winner for being compatible with polymer clay.
  • Most spray sealers don’t fully dry on polymer clay and stay sticky.
  • Results vary greatly depending on which polymer clay is used.
  • It’s not the propellants that degrade the clay, rather the sealer itself becomes tacky.
  • Spray Varathane and Minwax Fast-Drying Polyurethane will both dry nicely on polymer clay, but may scratch off some brands of clay.
  • Always test your spray sealer before using it on an important project.

Test tiles of black polymer clay ready to be coated with spray sealer.
Tiles of polymer clay waiting to be sprayed with sealant to test compatibility.

Testing Spray Sealers on Polymer Clay

Various brands of black polymer clay packages.I bought nine kinds of spray varnish and tested them on four brands of polymer clay, applied after baking. I made tiles of Sculpey III, Kato Polyclay, Premo, and Fimo Professional and thoroughly baked each tile. Each tile was wiped with isopropyl alcohol to remove any surface oils. Since humidity and temperature during application can cause problems, I chose a day that was 75°F (24°C) and 45% humidity and did all the spraying outdoors on a calm day. Three coats of each spray were applied following the directions on each can. Afterward, the tiles were stored in my studio at normal room temperature of 70°F – 82°F (21°C – 28°C). Humidity varied greatly during the test period and at times was close to 90%. Other times the room was closed up and AC was used.  At 24 hours, 1 week, and 1 month, the tiles were evaluated for stickiness, fingerprints, scratch resistance, cracking, crazing, and cloudiness. I used my fingernail to try to scratch the sealer off the tile. Peeling or obvious marring was considered a “fail”. I also evaluated the tiles for gloss level upon application and odor after 1 month. I will evaluate the tiles again at the six month point to see if anything has changed.

It should be noted that I used black clay merely so that I could more readily see any crazing or cloudiness that might occur. Other polymer clay artists have told me that different colors of clay, even within one brand, have different reactions to sealers, so your results may very easily differ from mine. Also, testing on black didn’t reveal if any of these sealers would turn yellow over time.

Even after a month of drying, many spray sealers are sticky on polymer clay. Read more at The Blue Bottle Tree.
Many spray sealers don’t dry on polymer clay and stay sticky and gummy.

About the Test Results

I was very surprised to see that no sealer behaved the same on different brands of clay. In general, spray sealers were the stickiest on Fimo Professional and were less sticky on Sculpey III. And every spray sealer except PYM II could be peeled or scratched off of Kato and Premo with my fingernail, but several of them were more durable on Sculpey III and Fimo Pro. These inconsistencies might explain why people are reporting good results with one spray sealer when others report that it gets tacky over time.

Duncan Super Matte Spray on black tiles of polymer clay.
Most spray sealers readily scratched off of Kato Polyclay.

As the humidity increased in my studio, the tiles became more sticky. If a tile was sticky at any time during the test period (after the initial 24 hours), then I considered that sealer to be a “fail”. Even a tiny amount of stickiness would make a bead stick to the wearer’s hair, or dust and pet fur stick to a figurine.

Sticky sealer on polymer clay test tiles collected cat fur and dust from the air.
Sticky, gummy sealers collect animal fur and dust from the air.

Several of the sealer/clay combinations were nearly perfect except that the sealer could be scratched with a fingernail. Obviously, you wouldn’t want to use these spray sealers for functional objects and jewelry. But for a figurine that will sit on a shelf, they’ll be suitable. I’ll identify those below.

It’s common for people to complain that the smell of spray varnishes can be quite strong. And yes, they’re pretty smelly during application. After 1 month, however, I don’t find any of the spray sealer varnishes to have any remaining smell. In fact, I can readily smell the Premo and Kato itself, but not the sealers.

Results of Spray Sealers on Polymer Clay

Patricia Nimrock’s Clear Acrylic Sealer

No longer compatible with polymer clay, Patricia Nimrock's spray sealer makes polymer clay sticky.Years ago, this brand was recommended as being the only one that was safe for polymer clay. But the formulation has changed over time (as has that of polymer clay) and I wanted to see if it still worked. It doesn’t. This glossy spray remained very sticky and tacky on all clays tested. All four samples readily took fingerprints and the sealer was easily scratched with my fingernail. Not Recommended.

Mod Podge Gloss Clear Acrylic Sealer

Mod Podge Acrylic Spray Sealer is not compatible with polymer clay and will remain sticky. Mod Podge is a trusted craft brand name and therefore clayers will reach for this one because it seems like a good idea. It is not. It remained sticky on every brand of clay tested. It was, however, fairly scratch resistant on Fimo Professional, but since it’s so sticky it can’t be practically used. (By the way, I don’t recommend the original Mod Podge brush-on as a sealer for polymer clay, either.) Not Recommended.

Varathane Gloss Polyurethane

Varathane spray was not sticky on polymer clay, however, it did peel.I was surprised to find that this spray is very similar to the Varathane brush-on that we all know and love. It goes on milky white and even smells the same. It has the same dry, smooth feel that Varathane in the can has. But for some reason, the spray action wasn’t very smooth. The spray was fairly coarse and gave a speckled coating on the clay that didn’t self-level. This gave a sort of orange peel surface texture (see photo below). Even though this was a can of gloss sealer, the effect was only what I’d call a semi-gloss. This spray sealer didn’t have even a hint of stickiness, but it also was readily scratched from Sculpey III, Premo and Kato with my fingernail. (For what it’s worth, brush-on Varathane can often be peeled from clay in the same way. In use on beads it doesn’t seem to matter much.) On black, spray Varathane gave a very slightly cloudy effect that wasn’t quite as clear as the other sealers. But for most things I wouldn’t find this to be a problem. Recommended for some purposes.

Spray Varathane peeled from Kato polymer clay and also gave an orange-peel textured surface. More about spray sealers for polymer clay at The Blue Bottle Tree.
This is Varathane Spray Gloss on a test tile made from Kato Polyclay. Note the orange-peel texture that the spray left and also note how readily the sealer can be scratched and peeled from the surface of the clay.

Krylon Triple-Thick Crystal Clear Glaze

Do not use Krylon Crystal Clear Glaze on polymer clay because it will turn sticky over time.This spray sealer is very commonly recommended for use with polymer clay and yet others complain bitterly about how it ruined their projects. I really, really wanted this spray to be a winner because it was exceedingly thick and glossy, making the clay look like it was coated in resin. But every one of my clay samples, all four brands, became sticky at some point during the month. At first I thought it was just slow drying, but no. It wasn’t sticky at one week, but at the one month point the stickiness returned. This sealer was easily scratched with a fingernail from Premo and Kato, but did hold up better with Sculpey III and Fimo. But there was also a fine crazing on Kato and Fimo. It was almost a winner for use with Sculpey III, but there was that annoying tackiness. But if you’re just doing Sculpey III, you might have better results than I did with this one, especially if you live in a dry climate. Not Recommended.

Rustoleum American Accents Gloss Clear

Rustoleum American Accents spray sealer is okay with Sculpey III, but not Premo or Fimo.This sealer was not as glossy as the Krylon. And it tested to be a perfect sealer on Sculpey III with no stickiness, fingerprints, peeling, or cloudiness. On Kato, it wasn’t sticky, but did peel readily and was just a tiny bit cloudy after a month. However, on both Premo and Fimo, this spray sealer was sticky and therefore unacceptable for use with polymer clay. If you’re just making figurines that will sit on a shelf, this would be a great sealer if you use Kato or Sculpey III. Limited Recommendation.

PYM II

PYM II is a fantastic spray sealer for polymer clay. Read more at The Blue Bottle Tree.This spray sealer is the “gold standard” for using with polymer clay and I’ve sung its praises before in a review that you can read here. It’s a very different kind of spray sealer made by a small company in Georgia in the US. It’s made for sealing paper, originally, but it works well with all brands of polymer clay. It’s not sticky or tacky, you can’t leave fingerprints in it, and it doesn’t scratch off polymer clay. I did see a tiny bit of scratching on Kato, but on the others the sealer was stuck very tight to the clay. I didn’t see any cloudiness with PYM II, but through conversation with Doug (the owner), I understand this can be a problem if it’s very humid during application. Doug says you can fix it, though, by simply heating your clay until it’s clear once again. Some people complain about the odor of PYM II, but compared to all the other sprays I used in this test, PYM was almost pleasant. Think of it as being like hair spray rather than spray paint. A lot of people use PYM as a first-coat fixative and then use brush-on sealers over the top for durability. Highly Recommended.

Minwax Fast-Drying Polyurethane Clear Gloss

Minwas Fast-Drying Polyurethane is safe on polymer clay. More at The Blue Bottle Tree.I really had to laugh at the name of this one. It was the slowest drying of all the sealers that I tested. In fact, it took so long to dry that I only put two coats on the test tiles. But even with two coats, this sealer had a nice glossy appearance. It took several days to fully dry and stop being tacky to the touch. But once fully dried, this sealer was not tacky or sticky on any of the clays that I tested and didn’t take fingerprints. It also didn’t have problems with crazing or getting cloudy. The only drawback of this sealer was that you could scratch it off Kato and Premo with a fingernail. On Sculpey III and Fimo Professional, Minwax Polyurethane was an excellent high gloss spray sealer. Limited Recommendation.

Duncan SS 330 Super Gloss Ceramic Sealer

Duncan Super Gloss Ceramic SealerI only chose this because I was ordering the one below and just included it in the order. Duncan is a brand of supplies for ceramic artists. This high gloss might work well on ceramic, but it was an epic fail on polymer clay. It was so gummy that it attracted cat hair and dust while just sitting on a shelf in my studio. The surface never really dried, so scratches I made with my fingernail on week one had self-levelled and “healed” by one month. This one has no place in polymer clay. Not Recommended.

Duncan SS 339 Super Matte Ceramic Sealer

Duncan Super Matte Ceramic Sealer is possibly safe on polymer clay.Recommended for polymer clay in a post by Karen Schofield, this is the only matte spray that I tested. Interestingly, it was a nice matte spray and gave a smooth, even surface. It was very matte, but not “dead matte”. In other words, light did reflect, but not a lot. At first I had great hopes for this sealer because it was not sticky or tacky at any point. But it very readily scratched off every brand of polymer clay that I tested. And after a month, the surface changed slightly. While not tacky, the surface feels sort of waxy. Like feeling waxed paper. It was not cloudy, but do keep in mind that all matte surface treatments will make your polymer clay appear slightly cloudy and will dull the colors a bit. I used some spare cardboard to hold the tiles when I sprayed them, and I kept the cardboard with the tiles. I can now see that the spray on the cardboard has begun to turn white and chalky. So I’m not so sure this spray will be suitable for the long-term. But I’m tentatively hopeful and it does deserve more exploration. But not as a durable sealer as it scratches off so readily. Not recommended...but will test further.

Recommendations by Clay Brand

Sculpey III

I’m not a fan of Sculpey III due to its brittle nature, but people do use it, so what’s the best spray sealer? There are more options with Sculpey III than the other clays. It seems to not have as much incompatibility as the other brands. If you need durability in a spray sealer, choose Rustoleum American Accents Gloss Clear, PYM II, or Minwax Fast-Drying Polyurethane Clear Gloss. If the item will sit on a shelf, add Varathane Spray to the list. Note: Adding a spray sealer will not make your piece more durable. If you’re getting breakage with Sculpey III, you’re expecting too much from it and you should try another brand of clay.

Kato Polyclay

Kato is a very durable and strong clay that is a favorite of caners and anyone who needs a strong result. But it’s also a difficult clay to make any sealer stick to. Of all the brands tested for this article, only PYM II was fairly durable on Kato. If the item will sit on a shelf and not be subject to wear, you could also use Varathane, Rustoleum American Accents Gloss Clear, PYM II, and Minwax Fast-Drying Polyurethane Clear Gloss.

Premo

I’m a fan of Premo, generally, as it’s a good all-purpose polymer clay that’s suitable for most anything you’d like to make. It does, however, have trouble staying hold of sealers and with the exception of PYM II, all spray sealers that I tested could be scraped off of Premo. If you need a durable spray sealer for Premo, PYM II is your answer. If you don’t need durability, however, you could also get by with using Varathane, and Minwax Fast-Drying Polyurethane Clear Gloss.

Fimo Professional

Formerly called Fimo Classic, this clay is very strong and perhaps more commonly available in Europe than in the US. Note that Fimo Soft and Fimo Effect may not give the same results that I found with Fimo Pro. In general, I noticed that if a sealer was going to be sticky with any clay, it was going to be sticky with Fimo Pro. There’s something in the clay that prevents many sealers from properly drying. However, sealers that peeled off the other clays readily stuck tight to this one. I found that Varathane, PYM II, and Minwax Fast-Drying Polyurethane Clear Gloss were all perfectly durable and compatible with Fimo Professional.

Many spray sealers for polymer clay leave the surface sticky and collecting cat fur and fingerprints.
Fingerprints, animal fur, and dust mar the surface of a sticky spray sealer on a polymer clay tile.

What’s the Bottom Line?

So all of that was a clear as mud, right? Well, as they say, nothing is ever simple. PYM II is still my pick for being the best spray sealer for polymer clay. But I can also say that Spray Varathane is a good alternative. As is MInwax Fast-Drying Polyurethane. I have also heard from others that Minwax Polycrylic Spray is good as well. Unfortunately, I can’t tell you if there’s a magic ingredient that’s causing some spray sealers to be sticky on polymer clay. The manufacturers of these materials don’t reveal their formulas. Also, what a specific brand has in its ingredient list may very readily change over time. So what works now may not work with product being sold a year or two from now.

Always Test

Because of the variability of polymer clay and craft product formulations, it’s always best to test any new material to see if it works for your purposes. Don’t take my word for it. If you’ve spent time creating something special, don’t spray it with a sealer without first doing some tests of your own. I’d hate to see your work ruined because a manufacturer changed their formula without changing the label.

It’s Not the Propellant

I’ve read on the internet (and may have even stated myself more than once) that the propellants in spray sealers “eat” or soften the clay over time. I don’t see any evidence of this being the case. In all of the tiles I tested, when I scratch the sticky sealer from the surface of the clay, the clay itself is undamaged. It’s the sealer itself that’s sticky, not the clay. This is good news because it means that it might be possible to remove the sticky sealer from a sticky project. I was able to remove every brand of spray sealer from their test tiles, except Mod Podge Clear Acrylic Sealer, by using straight 91% isopropyl alcohol.

I’m not an organic chemist, so I don’t know the chemistry, but I have been privvy to some conversations that suggest that plasticizer migration from the polymer clay might be causing the spray sealers to soften and become gummy. This does make sense to me as the problem also occurs with some brush-on acrylic paints and sealers. Make sure you are baking your clay fully to help minimize the free plasticizer. Also, this makes me think that very fresh polymer clay (which is very soft with fresh plasticizer) might have more problems with gummy sealers than older clay.  It’s just one more variable in this already-confusing subject!

What’s Next?

The purpose of these tests was merely to do quick elimination of brands of spray sealer for polymer clay. I was hoping to find a couple of sealers that worked well across the board, but there really wasn’t one except for PYM II. But depending on the clay you use, there are still some new options to try. I didn’t talk about HOW to use a spray sealer for polymer clay. That will come later. There are lots of strategies to discuss including using fixatives, spraying on raw clay, layering spray sealers with color and adding brush-on sealers. Our community is full of creative people who have shared so many fantastic ideas. Feel free to experiment. Remember, there is no one right way to use polymer clay and the possibilities are as endless as your imagination. Try things, experiment. You just never know what you’ll come up with.

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