The Reasons Certain Ceramic Glazes Become Limited Editions

When you pick up a dinner plate with a hypnotic, misty blue rim or a serving bowl streaked in molten copper and violet, you can usually feel it: this is not a color that will be around forever. As a tabletop stylist and pragmatic lifestyle curator, I have watched more than a few clients fall in love with a glaze, only to learn it is a short-run, “when it is gone, it is gone” finish.

Limited edition glazes are not just a marketing trick. Often the limitation comes directly from the chemistry of the glaze, the fragility of supply chains, or the realities of food safety and production. Understanding those forces helps you decide which pieces to collect, how to use them, and when to quietly buy that extra salad plate before it disappears.

In this article, I will unpack why certain ceramic glazes naturally become limited editions, drawing on technical insight from glaze specialists, museum and auction guides, and studio potters, then translate it into practical choices for your table and your home.

What We Really Mean By a “Limited Edition” Glaze

Glaze, in the most straightforward sense, is a glass-like coating fused to a ceramic body in the kiln. Christies’ specialists describe it as an impervious, glassy layer built mainly from silica, with other oxides added for color, texture, and melt behavior. Historically, glazes turned porous earthenware into usable containers; even with porcelain, which is less porous, glaze became an expressive, decorative skin.

When we talk about a limited edition glaze in the world of dinnerware and tabletop, we are usually talking about one of three things. Sometimes a glaze is limited because key raw materials are rare, expensive, or changing, so the studio cannot or does not want to produce it indefinitely. Other times, the glaze is technically demanding or finicky in firing; it looks magical under a very specific set of kiln conditions that are hard to repeat at large scale. Finally, a glaze may be tactically limited by the maker to create rarity and maintain a tight, evolving palette, much as art potters and antique kilns did in the past.

In practice, a “limited” glaze might be tied to a particular collection, to a season, or simply to the amount of a special material the studio can obtain. Once it is gone or reformulated, any tableware finished with that glaze becomes part of a short chapter in the maker’s history.

Inside the Glaze: Why Some Recipes Are Naturally Finite

A quick look at glaze structure

Glaze chemistry may sound intimidating, but a simplified picture goes a long way toward explaining why some finishes are hard to repeat. Ceramic Arts Network describes glazes as having three functional components. Glass formers, like silica, create the glassy phase. Fluxes lower the melting point and encourage the mixture to flow and vitrify. Refractories, rich in alumina and similar oxides, stiffen the melt and keep the glaze from simply running off the pot.

On top of that structure, you have colorants and opacifiers. Traditionally, these were raw metal oxides such as iron, copper, cobalt, and chromium. Today, stain manufacturers also supply engineered fritted colorants that combine oxides, silica, alumina, and opacifiers into stable pigments. Ceramic Arts Network notes that these modern stains are highly predictable but come with detailed firing limits: some should not be used with zinc, some demand a particular calcium range, and many are designed for specific kiln atmospheres.

Slip in the wrong material, change the flux balance, or shift the firing curve, and the same “recipe” can look utterly different. That fragility is one reason glaze effects that look wild, streaked, or layered often exist only in small, carefully managed runs.

Cool, art, and reactive glazes

In the retail glaze world, suppliers sometimes call these adventurous surfaces “cool” or “art” glazes. Big Ceramic Store describes them as decorative glazes prized for effects like running, breaking on edges, and color changes that reveal the form of the pot. They point out that results depend heavily on glaze thickness, clay body, temperature, and cooling schedule, so experimentation is essential. Layering several glazes over one another is explicitly encouraged to create unique finishes, with the understanding that no two firings will match exactly.

In working potters’ communities, the term “reactive glaze” also comes up regularly. One potter in a Mayco Mud Room Society group asks if there is any formal way to identify reactive glazes beyond intuition and test tiles, noting how often combinations “run” or behave unpredictably when layered. That question captures a key tension: the more responsive a glaze is to its environment, the more spectacular the results, and the harder it is to promise consistent outcomes in volume production.

Those same qualities make such glazes ideal candidates for limited editions. When you see a dinner plate where teal, sand, and charcoal are clearly playing with gravity and pooling in ways that feel alive, you are likely looking at a recipe with built-in constraints.

Reason One: Rare or Changing Ingredients

Historically scarce colorants and prestige glazes

Scarcity of glaze ingredients has shaped ceramic history for centuries. Williams Lawrence’s exploration of Chinese glazes highlights Tang dynasty sancai wares, where tricolored lead glazes were sometimes enriched with blue made from imported Persian cobalt. Because that cobalt was rare and expensive, blue-bearing sancai acted as a status marker; having it on your tomb figure suggested reach and wealth.

Later glazes, like the luminous blues and purples of Jun ware or the deep reds and streaked blues of flambé and oxblood glazes, relied on similarly sensitive color systems built around copper and iron in complex kiln atmospheres. Cerakey’s discussion of collecting ceramic art notes how Jun ware is famous for “one color before firing, a thousand variations after,” which tells you just how dependent those glazes are on finely balanced materials and firing.

When a glaze owes its identity to a narrow window of chemistry and a scarce colorant, it is fragile by nature. A small shift in ore purity, furnace technology, or trade routes can transform a “standard” color into a historical rarity overnight.

Contemporary rare elements and specialty pigments

Modern materials science has introduced an entirely new palette of rare elements into glaze and glass bodies. A study shared via Academia examines how gallium, rubidium, selenium, lanthanum, cerium, and erbium behave in glazed ceramics at various cones. The authors describe how these rare oxides and salts can generate new surface effects and colors not achievable with conventional coloring oxides.

They also note an important tradeoff. Producing nano-scale, high-purity oxides and fluxes yields harder, stronger, more predictable bodies and glazes, but the manufacturing pathways are long and expensive. Rubidium, for instance, is described as a very reactive alkali metal that ionizes easily and may yield striking results in reduction firings such as raku, yet its reactivity and rarity demand careful handling. Gallium oxide can create glossy, mirror-like coatings on glass and porcelain, but again, cost and process complexity limit its everyday use.

For a studio or factory, leaning on these rare elements often means accepting that a glaze will be a special project rather than a permanent colorway. A short run for a capsule collection, a commemorative series, or a limited-edition lamp makes sense; committing that same chemistry to a core dinnerware line does not.

Modern stain technology offers another version of this. Ceramic Arts Network points out that encapsulated stains containing cadmium can now provide reliable yellows-to-reds even at high cones. These inclusion pigments are designed to be stable and can be food-safe under controlled conditions, but any glaze that uses them on functional surfaces should be laboratory-tested for leaching. That extra burden of testing and the care these stains require further nudges them toward limited, carefully framed uses.

Nature, quarries, and supply chains

Even without exotic elements, glaze materials are not static. Heath Ceramics speaks candidly about how their glazes depend on natural minerals and clays, and how changing access to raw materials sometimes forces them to reformulate recipes to maintain a glaze’s character. The same glaze name on a box may mask quiet adjustments behind the scenes as quarry seams change or suppliers shift.

Ash-based glazes show this volatility even more clearly. Glazy’s overview of glaze types notes Nuka glazes built on rice husk ash and high-calcium fluxes, which produce bluish-white, milky surfaces when applied thickly. Studio Potter’s exploration of “weird and unusual raw materials” describes using bones, shells, kitty litter, and other calcium sources to create distinctive glazes or fuming effects. These approaches rely on the chemistry of a specific ash or material, and that chemistry in turn depends on plant species, soil, and burn conditions.

You simply cannot guarantee that the ash you collect next year will behave exactly like the ash you collected last year. In commercial settings, this reality translates into either heavy testing or quiet retirement. When a favorite feldspar or ash source disappears, the glaze attached to it often becomes, retrospectively, a limited edition.

Reason Two: Demanding Firing Conditions

Atmosphere-sensitive color that is hard to scale

Some of the most captivating glaze colors in tableware hinge on kiln atmosphere and firing profiles. Ceramic Arts Network’s and other technical discussions of colorants emphasize that copper, cobalt, iron, and chromium behave very differently in oxidation versus reduction, and that their responses are shaped by glaze alkalinity and flux choice.

An article on cool green and turquoise colors notes that copper in oxidation typically yields greens, while in strong reduction it can turn into oxblood reds. Around modest percentages in low-alumina alkaline glazes it produces bright transparent turquoise, but above higher percentages it can oversaturate into a matte metallic black. Chrome can give classic greens but can also shift toward yellow-green in highly alkaline glazes, or interact with tin and calcium to create pinks. Chrome and zinc, on the other hand, can react to form dull brown zinc chromate, an outcome most potters want to avoid.

Ash glazes fired in reduction often turn various greens because of iron in the ash, with tree species and mineral content shifting the final hue. Celadon glazes rely on controlled iron levels and carefully tuned alumina and flux content for their subtle gray-green to blue tones.

From a tabletop styling perspective, these glazes are exactly the ones that catch your eye: floating celadon pools in a soup bowl, streaked ash greens on a serving platter, copper reds that break to lavender at the rim. From a production perspective, they are notoriously sensitive to kiln load, shelf position, firing curve, and atmosphere. Maintaining the same result across thousands of place settings is a tall order. Limited runs make it possible to embrace the complexity for a defined period while keeping quality expectations realistic.

Glazes that love to move

Movement is another trait that is aesthetically irresistible and technically tricky. Big Ceramic Store’s overview of cool glazes describes low-fire lines that run, break, and flow: alligator-surface glazes that switch from matte to gloss as temperature changes, Magic Flow glazes that imitate traditional reduction ash glazes with wiggly runs, and crystal-bearing glazes where embedded crystals melt, spread, and create dramatic speckling.

These glazes are clearly marketed as creative tools, with the caveat that results vary widely and testing is crucial. In a similar spirit, a hobbyist in the Mayco Mud Room group worries about reactive glaze combinations that run too much, causing defects or even kiln damage.

On a vase, a dramatic flow line feels deliberate and sculptural. On a dinner plate, that same run might pool in the center, creating a thick, potentially brittle glass layer. For makers who care about functional ware, such glazes can be more comfortable on accent pieces, decorative chargers, or limited collections rather than as endlessly stocked dinner plates.

The hidden cost of testing every color

Behind every “new” glaze you see in a catalog lies a staggering amount of testing. Sue McLeod, writing about glaze testing, describes a glaze technology course where the class collectively ran around 1,500 tests: 128 base recipes and 45 colorant tests per base. Her core recommendation is that potters put at least one new test in every kiln firing, and make test tiles for every clay body used.

This mindset reveals why studios cannot simply add and keep every interesting glaze they develop. Each candidate recipe must be tested for how it behaves on different clay bodies, in varied thicknesses, at slightly hotter or cooler firings, and, for functional ware, for stability and fit. Many possibilities show up briefly as small studio runs or special collections, then give way to a more focused, sustainable palette.

When you are holding a limited edition glaze, you are often holding the tip of an iceberg of testing that the studio has decided to honor briefly, rather than commit to forever.

Reason Three: Food Safety and Functional Reality

Why some gorgeous glazes stay off the dinner table

For everyday tableware, beauty is only half the story; the surface also needs to be durable and food-safe. A guide to choosing glazes for functional ware explains that glazes must be matched to clay and firing range, and that underfired glazes can be cloudy, rough, or weak. Overfired glazes may slump or pool at the bottom of a piece and develop defects like blisters and pits. Neither extreme is ideal on plates that meet utensils and acidic foods daily.

Lead-free glazes are strongly recommended for functional ware, but even a lead-free label does not automatically guarantee safety. True food safety depends on glaze chemistry, firing schedule, clay body, and surface texture. Suppliers often suggest laboratory leach testing, especially when glazes contain heavy metals or inclusion stains, or when pieces will be sold for regular food use.

Ceramic Arts Network emphasizes this point with cadmium-containing inclusion stains, which can be food-safe if used correctly but may leach in some base glazes unless carefully formulated and tested. Studio Potter, in its exploration of household materials in glazes, goes even further and advises that foodsafe functional ware probably should not rely on experimental “oddball” materials such as soap powders or bone inlays, reserving those for decorative work guided by curiosity and testing.

Many of the most alluring glazes in studio catalogs are therefore deliberately steered away from dinner plates and toward decorative bowls, jars, and tiles. They appear in limited series, framed clearly as decorative surfaces, so that functionally neutral pieces carry the higher risk chemistry while everyday plates and mugs stick to proven bases.

Crazing, crackle, and surface character

Collectors of art pottery often love the signs that make a piece feel alive: fine crackling in the glaze, known as crazing, little popped glaze bubbles, or an area where the glaze skipped or crawled. Just Art Pottery’s terminology guide defines crazing as a network of fine cracks in the glaze (not the clay body), so fine you cannot feel them with a fingernail. They point out that crazing is extremely common on American art pottery and not usually considered damage in itself, though some collectors pay extra for uncrazed pieces from certain makers.

Other glaze effects are cataloged with equal nuance: glaze chips that affect only the glaze layer; peppering from tiny black carbon specks; glaze scale where flakes come off edges; glaze skips or crawls where the glaze never fully covered; glaze pops where bubbles burst; and kiln kisses where pots touched in the kiln and swapped patches of glaze.

From a styling perspective, these features can be charming on a vase or sculptural bowl, and historically they often do not disqualify a piece from “mint” condition if they originated in the kiln. For daily-use dinnerware, though, heavy crazing and exposed clay pores can trap food residues and stains. Homes and Antiques’ guide to antique ceramics notes that cleaning should be gentle and that dishwashers are best avoided for valuable pieces, partly because heat and pressure can exacerbate existing flaws.

The upshot is that many modern crackle and crazed glazes are kept intentionally in the realm of decorative ware or limited series, especially if the maker cannot confidently demonstrate that the surface passes leach and durability testing for repeated food contact.

Reason Four: Intentional Rarity and the Culture of Collecting

Glaze as a signature for artists and brands

Glaze has always been central to ceramic identity. Cerakey’s exploration of ceramic art as a hybrid of culture, craft, and investment highlights Ru kiln pieces with sky-blue glazes, of which fewer than one hundred survive, and Jun ware with its famously unpredictable blues and purples. Those glazes are not only technical achievements; they are also signatures of specific kilns and eras that drive immense value at auction.

Modern designers channel that same spirit. Williams Lawrence describes how flambé and oxblood glazes, born from imperial attempts to recreate Jun ware, evolved into glossy red surfaces with bluish-purple streaks that captivated both Qing dynasty emperors and later European ceramists. Contemporary designs echo Jun ware through thick, speckled midnight glazes on faceted forms, and reinterpret flambé in ombré lamps that fade from warm white to deep red.

For a brand or studio, naming and framing a particular glaze as part of a story instantly positions it as something more than “blue.” It becomes identifiable and collectible. That narrative framing makes it natural to offer certain glazes in limited cycles, keeping them special while allowing room for new experiments.

Designing scarcity into tabletop collections

Antique dealers often use the acronym RADAR to think about value: rarity, aesthetics, desirability, authenticity, and condition. Hemswell’s guide to antique ceramics emphasizes that rarity can come from small original production runs, unusual shapes, or the survival of only a few examples. Fashion cycles and interior trends then influence desirability, causing some categories to rise and fall in popularity over time.

Cerakey expands on this by positioning ceramics as a hybrid asset class where rarity and craftsmanship intersect with cultural significance and market performance. Auction records cited there show just how powerfully a particular glaze and form combination can appreciate when all five RADAR elements align.

Contemporary studios understand this dynamic. Heath Ceramics, for example, openly embraces glaze variation as part of its brand identity, acknowledging that no two pieces emerge identical from their kilns. Maison Castiglione speaks of ceramics as a medium that celebrates raw material, gesture, and sublimated imperfections rather than industrial uniformity.

Within that context, rotating glazes seasonally, offering small runs tied to collaborations, or retiring colors once their story feels complete becomes a deliberate strategy. It keeps the catalog fresh, respects the realities of materials and firing, and nurtures a community of collectors who appreciate owning something that will not be reproduced indefinitely.

As a stylist, I often suggest that clients treat these glazes the way they would limited-edition prints. If the color harmonizes beautifully with your linens, art, and architecture, and the maker is known for evolving their palette, it is usually wise to acquire a comfortable number of pieces while you can.

Reason Five: Time, Discontinuation, and Studio Evolution

When suppliers stop making the magic

Sometimes a glaze becomes limited not because the ceramic studio intended it, but because the upstream supply has shifted. A discussion in the Mayco Mud Room Society about reviving old Duncan glazes illustrates this. A potter describes inheriting very old, completely dried Duncan jars and choosing to gently revive them with distilled water rather than discard them. The story highlights how even large commercial lines are not permanent; they age, go out of production, and survive only in jars on studio shelves and in the pieces already fired.

That same pattern plays out at every scale. A factory line might rely on a commercial “cool” glaze that is suddenly discontinued. A studio might use a specific fritted stain whose manufacturer changes formulation or retires certain colors. Once existing stock is used or once the glaze is reformulated, the original finish is effectively a closed chapter. Any tableware produced with that exact batch becomes, whether planned or not, a limited edition.

Studios refine their palette over time

Glaze testing and palette curation is an ongoing process, not a one-time decision. Sue McLeod’s recommendation to include at least one test in every firing captures the steady rhythm of experimentation in a studio. Heath Ceramics, with its long history, has also described how staff learn the quirks of particular kilns and how glazes evolve while preserving their core character.

Over years, makers learn which glazes align with their identity, which ones are economical to produce, and which ones their customers actually live with. Early experiments might be vibrant but hard to photograph consistently, or exquisite in person but overly dominant on a full table. Those glazes may appear briefly in small collections and then quietly disappear as the maker’s vision sharpens.

For clients and collectors, this means some of the most intriguing glazes in your cupboard may be from transitional periods in a studio’s evolution. They tell a story of searching and refining that will not be repeated exactly.

Practical Advice: Choosing and Living With Limited Edition Glazes

Recognizing a likely limited-edition glaze

You do not need to be a materials scientist to sense when a glaze is likely to be short-run. In showrooms and studios, I look for a combination of narrative and behavior.

If the maker describes the glaze using words like ash, crystal, cool, art, or reactive, or emphasizes that no two pieces are alike because of kiln variation, that is a sign of complex chemistry or firing conditions. Glazes whose surfaces include dramatic crystals, pronounced runs, or strong breaking over edges, as described in low-fire lines like Duncan Crystals and Crackles or Laguna Mystic glazes, are often more difficult to standardize. Nuka-style glazes that rely on specific ash, or heavily variegated greens and blues shaped by copper, chrome, and cobalt, also hint at narrow windows of success.

On the marketing side, clear signals include named glazes tied to a particular collection or collaboration, and language that frames them as seasonal or “small batch.” Because the culture of collecting ceramics values rarity and authenticity, many brands are now transparent when a glaze is intentionally limited, which allows you to plan accordingly.

Here is a simple way to think about it.

Clue from the maker or showroom	What it often suggests about the glaze
Emphasis on ash, crystals, reactive, or “cool” effects	Chemically complex, high-variation glaze likely managed in smaller runs
Strong piece-to-piece variation visible on the shelf	Surface highly sensitive to hand application and kiln position
Story of rare materials, historic inspiration, or special ash	Dependency on specific materials that may not be indefinitely available
Labeling as seasonal, collaboration-based, or small batch	Intentional design choice to keep the glaze limited

None of these clues guarantee scarcity, but together they help you read between the lines.

Styling limited glazes on a real table

For everyday living, limited edition glazes shine when you treat them as focal points rather than trying to build your entire cabinet around them. I often encourage clients to choose a calm, durable base dinnerware in a neutral glossy or satin clear over white or light stoneware, then layer limited glazes as accents.

Think of dessert plates in a Jun-inspired lavender-blue perched on top of simple white dinner plates, or a single flambé-style serving bowl anchoring a buffet of quieter dishes. Variegated greens and blues from copper and ash glazes look particularly beautiful against natural linens and woods, where their complexity reads as a conversation with the rest of the room rather than a competing shout of color.

When mixing, pay attention to value and intensity more than precise hue. A misty celadon bowl can sit comfortably beside a smoky gray plate if their overall lightness is similar, while a deep oxblood or midnight blue piece often wants to be the dark anchor in an arrangement, balanced by paler neighbors.

Caring for special surfaces

Because limited edition glazes often carry more experimental chemistry or complex surfaces, they deserve considerate care. Homes and Antiques recommends a simple structural check: gently tap a ceramic piece and listen for a clear ring, which suggests sound structure. For cleaning, they advise placing pieces on a stable surface, using warm water with mild detergent and cotton swabs, avoiding unglazed areas, and drying carefully by hand. Dishwashers, with their heat and water pressure, are discouraged for valuable ceramics.

Crackled or heavily textured glazes need particular attention. Crazing, described by Just Art Pottery as fine glaze crackling that you cannot feel with a fingernail, is common and often accepted on decorative ware, but it can harbor stains. For special tableware, I suggest reserving heavily crazed or porous glazes for drier foods, centerpieces, or occasional use, and using smoother, well-fused surfaces for daily meals.

If a cherished limited glaze piece does suffer a break, consider repair approaches that respect its story. Homes and Antiques notes the tradition of kintsugi, where broken ceramics are rejoined with lacquer mixed with precious metals, turning cracks into visible, celebrated lines. On a spectacular but irreplaceable platter, such a repair can feel more honest and emotionally resonant than an invisible restoration.

Buying with both heart and head

Rarity alone does not guarantee that a glaze will age well in your life. Hemswell’s RADAR framework is helpful here. Rarity matters, but so do aesthetics, desirability, authenticity, and condition. Cerakey reminds us that collecting ceramics is both an emotional and an intellectual pleasure: it is about owning pieces of history and artistry that also have potential financial value.

When you are considering a limited edition glaze for functional ware, ask the maker direct questions. Is the glaze intended for food contact or decorative use only. Has it been tested on the clay body used. How does it hold up to cutlery and repeated washing. The best studios and brands are happy to share that information.

Then listen to your own instincts. Does this glaze genuinely harmonize with how you cook, entertain, and live, or are you primarily drawn to its rarity. A small collection of pieces you reach for often will bring far more joy than a cupboard full of delicate colors you are afraid to use.

Brief FAQ

Q: Are reactive or “cool” glazes a bad idea for everyday dinnerware?

Not inherently, but they require thoughtful placement. Suppliers describe cool or art glazes as highly variable and often recommend testing for thickness, clay body, and firing schedule. If a glaze is certified food-safe on its intended clay and firing range, it can be perfectly usable on dinnerware. In my own practice, I like to use the most reactive, running glazes on serving pieces, dessert plates, or the outside of bowls and mugs, pairing them with more controlled, well-tested glazes on the surfaces that meet food and utensils most directly.

Q: Does crazing ruin a glaze?

In the art pottery world, crazing is usually treated as a characteristic rather than damage, provided it formed in the kiln. Just Art Pottery notes that uncrazed examples of some famous lines are actually uncommon, and collectors expect some crackling. For functional ware, the calculus is different. Fine crazing on a decorative vase is not problematic; the same texture on a soup bowl may be less ideal because it can absorb stains over time. If you love the look of crackle, consider using those pieces for dry foods, fruit, or on the table as sculptural accents rather than as your deepest, most frequently washed bowls.

Q: How do I future-proof my table if my favorite glaze is limited?

Think in layers. Start with a timeless base dinnerware line that is likely to stay in production and is easy to replace. Then add your limited edition glaze in a few key forms that give you flexibility: salad or dessert plates that stack over your base plates, multipurpose serving bowls, or a pair of statement platters. If budget allows, buy one or two extra of the smallest, most breakable pieces, such as side plates, so a single accident does not unbalance your set.

When you understand why a glaze is limited, your relationship with it changes. It stops being a fleeting trend and becomes a deliberate choice: an embrace of particular materials, kilns, and hands at a moment in time. On a well-set table, those choices read as quiet depth. They tell your guests that you care about more than matching tones, that you are willing to live with a bit of unpredictability and history in exchange for a surface that could not have been made any other way.

References

1. https://www.academia.edu/8312440/Uses_of_The_Rare_Elements_into_Ceramic_Glazes_and_Glass_Bodies
2. https://www.floridamuseum.ufl.edu/histarch/ceramic-types/introduction/
3. https://aura.alfred.edu/server/api/core/bitstreams/3aadda50-bddf-47d4-954d-024e1a47a8a2/content
4. https://studiopotter.org/weird-and-unusual-raw-materials
5. https://help.glazy.org/concepts/types
6. https://community.ceramicartsdaily.org/topic/16685-confused-over-earthenware-and-glazes/
7. https://ceramicartsnetwork.org/daily/article/A-Super-Simple-Analogy-to-Help-You-Understand-Glaze-Structure
8. https://www.christies.com/en/stories/glazes-a-chinese-ceramics-collectors-guide-86302474ea03458fbb1bfc02bef58159
9. https://bigceramicstore.com/pages/info-ceramics-tips-tip78_cool_glazes
10. https://www.hemswell-antiques.com/blog/the-world-of-antique-ceramic-what-s-valuable-and-what-s-not